diff --git a/compiler/cbuilderbase.nim b/compiler/cbuilderbase.nim
index 19f3914d41f5..d6b71645fcb6 100644
--- a/compiler/cbuilderbase.nim
+++ b/compiler/cbuilderbase.nim
@@ -1,44 +1,56 @@
+import ropes, int128
+
 type
-  Snippet = string
-  Builder = string
+  Snippet* = string
+  Builder* = object
+    buf*: string
+
+template newBuilder*(s: string): Builder =
+  Builder(buf: s)
+
+proc extract*(builder: Builder): Snippet =
+  builder.buf
+
+proc add*(builder: var Builder, s: string) =
+  builder.buf.add(s)
 
-template newBuilder(s: string): Builder =
-  s
+proc add*(builder: var Builder, s: char) =
+  builder.buf.add(s)
 
-proc addIntValue(builder: var Builder, val: int) =
-  builder.addInt(val)
+proc addIntValue*(builder: var Builder, val: int) =
+  builder.buf.addInt(val)
 
-proc addIntValue(builder: var Builder, val: int64) =
-  builder.addInt(val)
+proc addIntValue*(builder: var Builder, val: int64) =
+  builder.buf.addInt(val)
 
-proc addIntValue(builder: var Builder, val: uint64) =
-  builder.addInt(val)
+proc addIntValue*(builder: var Builder, val: uint64) =
+  builder.buf.addInt(val)
 
-proc addIntValue(builder: var Builder, val: Int128) =
-  builder.addInt128(val)
+proc addIntValue*(builder: var Builder, val: Int128) =
+  builder.buf.addInt128(val)
 
-template cIntValue(val: int): Snippet = $val
-template cIntValue(val: int64): Snippet = $val
-template cIntValue(val: uint64): Snippet = $val
-template cIntValue(val: Int128): Snippet = $val
+template cIntValue*(val: int): Snippet = $val
+template cIntValue*(val: int64): Snippet = $val
+template cIntValue*(val: uint64): Snippet = $val
+template cIntValue*(val: Int128): Snippet = $val
 
 import std/formatfloat
 
-proc addFloatValue(builder: var Builder, val: float) =
-  builder.addFloat(val)
+proc addFloatValue*(builder: var Builder, val: float) =
+  builder.buf.addFloat(val)
 
-template cFloatValue(val: float): Snippet = $val
+template cFloatValue*(val: float): Snippet = $val
 
-proc int64Literal(i: BiggestInt; result: var Builder) =
+proc addInt64Literal*(result: var Builder; i: BiggestInt) =
   if i > low(int64):
     result.add "IL64($1)" % [rope(i)]
   else:
     result.add "(IL64(-9223372036854775807) - IL64(1))"
 
-proc uint64Literal(i: uint64; result: var Builder) =
+proc addUint64Literal*(result: var Builder; i: uint64) =
   result.add rope($i & "ULL")
 
-proc intLiteral(i: BiggestInt; result: var Builder) =
+proc addIntLiteral*(result: var Builder; i: BiggestInt) =
   if i > low(int32) and i <= high(int32):
     result.addIntValue(i)
   elif i == low(int32):
@@ -49,19 +61,19 @@ proc intLiteral(i: BiggestInt; result: var Builder) =
   else:
     result.add "(IL64(-9223372036854775807) - IL64(1))"
 
-proc intLiteral(i: Int128; result: var Builder) =
-  intLiteral(toInt64(i), result)
+proc addIntLiteral*(result: var Builder; i: Int128) =
+  addIntLiteral(result, toInt64(i))
 
-proc cInt64Literal(i: BiggestInt): Snippet =
+proc cInt64Literal*(i: BiggestInt): Snippet =
   if i > low(int64):
     result = "IL64($1)" % [rope(i)]
   else:
     result = "(IL64(-9223372036854775807) - IL64(1))"
 
-proc cUint64Literal(i: uint64): Snippet =
+proc cUint64Literal*(i: uint64): Snippet =
   result = $i & "ULL"
 
-proc cIntLiteral(i: BiggestInt): Snippet =
+proc cIntLiteral*(i: BiggestInt): Snippet =
   if i > low(int32) and i <= high(int32):
     result = rope(i)
   elif i == low(int32):
@@ -72,5 +84,5 @@ proc cIntLiteral(i: BiggestInt): Snippet =
   else:
     result = "(IL64(-9223372036854775807) - IL64(1))"
 
-proc cIntLiteral(i: Int128): Snippet =
+proc cIntLiteral*(i: Int128): Snippet =
   result = cIntLiteral(toInt64(i))
diff --git a/compiler/cbuilderdecls.nim b/compiler/cbuilderdecls.nim
index d717c6ee2e90..70d7cc364fb3 100644
--- a/compiler/cbuilderdecls.nim
+++ b/compiler/cbuilderdecls.nim
@@ -42,6 +42,18 @@ template addVarWithType(builder: var Builder, kind: VarKind = Local, name: strin
   builder.add(name)
   builder.add(";\n")
 
+template addVarWithInitializer(builder: var Builder, kind: VarKind = Local, name: string,
+                               typ: Snippet, initializerBody: typed) =
+  ## adds a variable declaration to the builder, with
+  ## `initializerBody` building the initializer. initializer must be provided
+  builder.addVarHeader(kind)
+  builder.add(typ)
+  builder.add(" ")
+  builder.add(name)
+  builder.add(" = ")
+  initializerBody
+  builder.add(";\n")
+
 template addVarWithTypeAndInitializer(builder: var Builder, kind: VarKind = Local, name: string,
                                       typeBody, initializerBody: typed) =
   ## adds a variable declaration to the builder, with `typeBody` building the type, and
@@ -252,12 +264,12 @@ proc startSimpleStruct(obj: var Builder; m: BModule; name: string; baseType: Sni
     obj.add(baseType)
   obj.add(" ")
   obj.add("{\n")
-  result.preFieldsLen = obj.len
+  result.preFieldsLen = obj.buf.len
   if result.baseKind == bcSupField:
     obj.addField(name = "Sup", typ = baseType)
 
 proc finishSimpleStruct(obj: var Builder; m: BModule; info: StructBuilderInfo) =
-  if info.baseKind == bcNone and info.preFieldsLen == obj.len:
+  if info.baseKind == bcNone and info.preFieldsLen == obj.buf.len:
     # no fields were added, add dummy field
     obj.addField(name = "dummy", typ = "char")
   if info.named:
@@ -308,7 +320,7 @@ proc startStruct(obj: var Builder; m: BModule; t: PType; name: string; baseType:
     obj.add(baseType)
   obj.add(" ")
   obj.add("{\n")
-  result.preFieldsLen = obj.len
+  result.preFieldsLen = obj.buf.len
   case result.baseKind
   of bcNone:
     # rest of the options add a field or don't need it due to inheritance,
@@ -328,7 +340,7 @@ proc startStruct(obj: var Builder; m: BModule; t: PType; name: string; baseType:
     obj.addField(name = "Sup", typ = baseType)
 
 proc finishStruct(obj: var Builder; m: BModule; t: PType; info: StructBuilderInfo) =
-  if info.baseKind == bcNone and info.preFieldsLen == obj.len and
+  if info.baseKind == bcNone and info.preFieldsLen == obj.buf.len and
       t.itemId notin m.g.graph.memberProcsPerType:
     # no fields were added, add dummy field
     obj.addField(name = "dummy", typ = "char")
diff --git a/compiler/cbuilderstmts.nim b/compiler/cbuilderstmts.nim
index a96571d1b8b4..e2d272e79524 100644
--- a/compiler/cbuilderstmts.nim
+++ b/compiler/cbuilderstmts.nim
@@ -93,6 +93,32 @@ template addElseBranch(builder: var Builder, stmt: var IfStmt, body: typed) =
   body
   builder.add("}")
 
+proc addForRangeHeader(builder: var Builder, i, start, bound: Snippet, inclusive: bool = false) =
+  builder.add("for (")
+  builder.add(i)
+  builder.add(" = ")
+  builder.add(start)
+  builder.add("; ")
+  builder.add(i)
+  if inclusive:
+    builder.add(" <= ")
+  else:
+    builder.add(" < ")
+  builder.add(bound)
+  builder.add("; ")
+  builder.add(i)
+  builder.add("++) {\n")
+
+template addForRangeExclusive(builder: var Builder, i, start, bound: Snippet, body: typed) =
+  addForRangeHeader(builder, i, start, bound, false)
+  body
+  builder.add("}\n")
+
+template addForRangeInclusive(builder: var Builder, i, start, bound: Snippet, body: typed) =
+  addForRangeHeader(builder, i, start, bound, true)
+  body
+  builder.add("}\n")
+
 template addScope(builder: var Builder, body: typed) =
   builder.add("{")
   body
diff --git a/compiler/ccgcalls.nim b/compiler/ccgcalls.nim
index 788f7a470bde..5ac567c0b265 100644
--- a/compiler/ccgcalls.nim
+++ b/compiler/ccgcalls.nim
@@ -209,8 +209,7 @@ proc genOpenArraySlice(p: BProc; q: PNode; formalType, destType: PType; prepareF
       result = ("($3*)(($1)+($2))" % [rdLoc(a), rdLoc(b), dest],
                 lengthExpr)
     else:
-      var lit = newRopeAppender()
-      intLiteral(first, lit)
+      let lit = cIntLiteral(first)
       result = ("($4*)($1)+(($2)-($3))" %
         [rdLoc(a), rdLoc(b), lit, dest],
         lengthExpr)
diff --git a/compiler/ccgexprs.nim b/compiler/ccgexprs.nim
index 78e9e5e280cd..1be7f2dc2b13 100644
--- a/compiler/ccgexprs.nim
+++ b/compiler/ccgexprs.nim
@@ -34,15 +34,15 @@ proc genLiteral(p: BProc, n: PNode, ty: PType; result: var Builder) =
       else: k = tyNil # don't go into the case variant that uses 'ty'
     case k
     of tyChar, tyNil:
-      intLiteral(n.intVal, result)
+      result.addIntLiteral(n.intVal)
     of tyBool:
       if n.intVal != 0: result.add "NIM_TRUE"
       else: result.add "NIM_FALSE"
-    of tyInt64: int64Literal(n.intVal, result)
-    of tyUInt64: uint64Literal(uint64(n.intVal), result)
+    of tyInt64: result.addInt64Literal(n.intVal)
+    of tyUInt64: result.addUint64Literal(uint64(n.intVal))
     else:
       result.addCast(getTypeDesc(p.module, ty)):
-        intLiteral(n.intVal, result)
+        result.addIntLiteral(n.intVal)
   of nkNilLit:
     let k = if ty == nil: tyPointer else: skipTypes(ty, abstractVarRange).kind
     if k == tyProc and skipTypes(ty, abstractVarRange).callConv == ccClosure:
@@ -51,17 +51,14 @@ proc genLiteral(p: BProc, n: PNode, ty: PType; result: var Builder) =
       if id == p.module.labels:
         # not found in cache:
         inc(p.module.labels)
-        var data = newBuilder("")
-        data.addVarWithTypeAndInitializer(kind = Const, name = tmpName):
-          data.add(getTypeDesc(p.module, ty))
-        do:
+        let t = getTypeDesc(p.module, ty)
+        p.module.s[cfsStrData].addVarWithInitializer(kind = Const, name = tmpName, typ = t):
           var closureInit: StructInitializer
-          data.addStructInitializer(closureInit, kind = siOrderedStruct):
-            data.addField(closureInit, name = "ClP_0"):
-              data.add("NIM_NIL")
-            data.addField(closureInit, name = "ClE_0"):
-              data.add("NIM_NIL")
-        p.module.s[cfsStrData].add(data)
+          p.module.s[cfsStrData].addStructInitializer(closureInit, kind = siOrderedStruct):
+            p.module.s[cfsStrData].addField(closureInit, name = "ClP_0"):
+              p.module.s[cfsStrData].add("NIM_NIL")
+            p.module.s[cfsStrData].addField(closureInit, name = "ClE_0"):
+              p.module.s[cfsStrData].add("NIM_NIL")
       result.add tmpName
     elif k in {tyPointer, tyNil, tyProc}:
       result.add rope("NIM_NIL")
@@ -107,7 +104,7 @@ proc genRawSetData(cs: TBitSet, size: int; result: var Builder) =
           result.add "0123456789abcdef"[cs[i] div 16]
           result.add "0123456789abcdef"[cs[i] mod 16]
   else:
-    intLiteral(cast[BiggestInt](bitSetToWord(cs, size)), result)
+    result.addIntLiteral(cast[BiggestInt](bitSetToWord(cs, size)))
 
 proc genSetNode(p: BProc, n: PNode; result: var Builder) =
   var size = int(getSize(p.config, n.typ))
@@ -118,12 +115,9 @@ proc genSetNode(p: BProc, n: PNode; result: var Builder) =
     if id == p.module.labels:
       # not found in cache:
       inc(p.module.labels)
-      var data = newBuilder("")
-      data.addVarWithTypeAndInitializer(kind = Const, name = tmpName):
-        data.add(getTypeDesc(p.module, n.typ))
-      do:
-        genRawSetData(cs, size, data)
-      p.module.s[cfsStrData].add(data)
+      let td = getTypeDesc(p.module, n.typ)
+      p.module.s[cfsStrData].addVarWithInitializer(kind = Const, name = tmpName, typ = td):
+        genRawSetData(cs, size, p.module.s[cfsStrData])
     result.add tmpName
   else:
     genRawSetData(cs, size, result)
@@ -1065,8 +1059,9 @@ proc genFieldCheck(p: BProc, e: PNode, obj: Rope, field: PSym) =
       # passing around `TLineInfo` + the set of files in the project.
       msg.add toFileLineCol(p.config, e.info) & " "
     msg.add genFieldDefect(p.config, field.name.s, disc.sym)
-    var strLit = newRopeAppender()
-    genStringLiteral(p.module, newStrNode(nkStrLit, msg), strLit)
+    var strLitBuilder = newBuilder("")
+    genStringLiteral(p.module, newStrNode(nkStrLit, msg), strLitBuilder)
+    let strLit = extract(strLitBuilder)
 
     ## discriminant check
     let rt = rdLoc(test)
@@ -1456,7 +1451,7 @@ proc genStrConcat(p: BProc, e: PNode, d: var TLoc) =
   var a: TLoc
   var tmp: TLoc = getTemp(p, e.typ)
   var L = 0
-  var appends = newBuilder("")
+  var appends: seq[Snippet] = @[]
   var lens: seq[Snippet] = @[]
   for i in 0..<e.len - 1:
     # compute the length expression:
@@ -1465,23 +1460,21 @@ proc genStrConcat(p: BProc, e: PNode, d: var TLoc) =
     let ra = rdLoc(a)
     if skipTypes(e[i + 1].typ, abstractVarRange).kind == tyChar:
       inc(L)
-      appends.addCallStmt(cgsymValue(p.module, "appendChar"),
-        rstmp,
-        ra)
+      appends.add(cCall(cgsymValue(p.module, "appendChar"), rstmp, ra))
     else:
       if e[i + 1].kind in {nkStrLit..nkTripleStrLit}:
         inc(L, e[i + 1].strVal.len)
       else:
         lens.add(lenExpr(p, a))
-      appends.addCallStmt(cgsymValue(p.module, "appendString"),
-        rstmp,
-        ra)
+      appends.add(cCall(cgsymValue(p.module, "appendString"), rstmp, ra))
   var exprL = cIntValue(L)
   for len in lens:
     exprL = cOp(Add, "NI", exprL, len)
   p.s(cpsStmts).addAssignmentWithValue(tmp.snippet):
     p.s(cpsStmts).addCall(cgsymValue(p.module, "rawNewString"), exprL)
-  p.s(cpsStmts).add appends
+  for append in appends:
+    p.s(cpsStmts).addStmt():
+      p.s(cpsStmts).add(append)
   if d.k == locNone:
     d = tmp
   else:
@@ -1502,7 +1495,7 @@ proc genStrAppend(p: BProc, e: PNode, d: var TLoc) =
   #  }
   var
     a, call: TLoc
-    appends = newBuilder("")
+    appends: seq[Snippet] = @[]
   assert(d.k == locNone)
   var L = 0
   var lens: seq[Snippet] = @[]
@@ -1514,17 +1507,13 @@ proc genStrAppend(p: BProc, e: PNode, d: var TLoc) =
     let ra = rdLoc(a)
     if skipTypes(e[i + 2].typ, abstractVarRange).kind == tyChar:
       inc(L)
-      appends.addCallStmt(cgsymValue(p.module, "appendChar"),
-        rsd,
-        ra)
+      appends.add(cCall(cgsymValue(p.module, "appendChar"), rsd, ra))
     else:
       if e[i + 2].kind in {nkStrLit..nkTripleStrLit}:
         inc(L, e[i + 2].strVal.len)
       else:
         lens.add(lenExpr(p, a))
-      appends.addCallStmt(cgsymValue(p.module, "appendString"),
-        rsd,
-        ra)
+      appends.add(cCall(cgsymValue(p.module, "appendString"), rsd, ra))
   var exprL = cIntValue(L)
   for len in lens:
     exprL = cOp(Add, "NI", exprL, len)
@@ -1535,15 +1524,15 @@ proc genStrAppend(p: BProc, e: PNode, d: var TLoc) =
       exprL)
   else:
     call = initLoc(locCall, e, OnHeap)
-    var callRes = newBuilder("")
     let rd = rdLoc(dest)
-    callRes.addCall(cgsymValue(p.module, "resizeString"),
+    call.snippet = cCall(cgsymValue(p.module, "resizeString"),
       rd,
       exprL)
-    call.snippet = callRes
     genAssignment(p, dest, call, {})
     gcUsage(p.config, e)
-  p.s(cpsStmts).add appends
+  for append in appends:
+    p.s(cpsStmts).addStmt():
+      p.s(cpsStmts).add(append)
 
 proc genSeqElemAppend(p: BProc, e: PNode, d: var TLoc) =
   # seq &= x  -->
@@ -1553,13 +1542,11 @@ proc genSeqElemAppend(p: BProc, e: PNode, d: var TLoc) =
   var b = initLocExpr(p, e[2])
   let seqType = skipTypes(e[1].typ, {tyVar})
   var call = initLoc(locCall, e, OnHeap)
-  var callRes = newBuilder("")
   let ra = rdLoc(a)
-  callRes.addCast(getTypeDesc(p.module, e[1].typ)):
-    callRes.addCall(cgsymValue(p.module, "incrSeqV3"),
+  call.snippet = cCast(getTypeDesc(p.module, e[1].typ),
+    cCall(cgsymValue(p.module, "incrSeqV3"),
       if not p.module.compileToCpp: cCast(ptrType("TGenericSeq"), ra) else: ra,
-      genTypeInfoV1(p.module, seqType, e.info))
-  call.snippet = callRes
+      genTypeInfoV1(p.module, seqType, e.info)))
   # emit the write barrier if required, but we can always move here, so
   # use 'genRefAssign' for the seq.
   genRefAssign(p, a, call)
@@ -1589,12 +1576,10 @@ proc rawGenNew(p: BProc, a: var TLoc, sizeExpr: Rope; needsInit: bool) =
 
   if optTinyRtti in p.config.globalOptions:
     let fnName = cgsymValue(p.module, if needsInit: "nimNewObj" else: "nimNewObjUninit")
-    var bres = newBuilder("")
-    bres.addCast(getTypeDesc(p.module, typ)):
-      bres.addCall(fnName,
+    b.snippet = cCast(getTypeDesc(p.module, typ),
+      cCall(fnName,
         sizeExpr,
-        cAlignof(getTypeDesc(p.module, bt)))
-    b.snippet = bres
+        cAlignof(getTypeDesc(p.module, bt))))
     genAssignment(p, a, b, {})
   else:
     let ti = genTypeInfoV1(p.module, typ, a.lode.info)
@@ -1625,12 +1610,10 @@ proc rawGenNew(p: BProc, a: var TLoc, sizeExpr: Rope; needsInit: bool) =
       if p.config.selectedGC == gcGo:
         # newObjRC1() would clash with unsureAsgnRef() - which is used by gcGo to
         # implement the write barrier
-        var bres = newBuilder("")
-        bres.addCast(getTypeDesc(p.module, typ)):
-          bres.addCall(cgsymValue(p.module, "newObj"),
+        b.snippet = cCast(getTypeDesc(p.module, typ),
+          cCall(cgsymValue(p.module, "newObj"),
             ti,
-            sizeExpr)
-        b.snippet = bres
+            sizeExpr))
         let raa = addrLoc(p.config, a)
         let rb = b.rdLoc
         p.s(cpsStmts).addCallStmt(cgsymValue(p.module, "unsureAsgnRef"),
@@ -1638,22 +1621,18 @@ proc rawGenNew(p: BProc, a: var TLoc, sizeExpr: Rope; needsInit: bool) =
           rb)
       else:
         # use newObjRC1 as an optimization
-        var bres = newBuilder("")
-        bres.addCast(getTypeDesc(p.module, typ)):
-          bres.addCall(cgsymValue(p.module, "newObjRC1"),
+        b.snippet = cCast(getTypeDesc(p.module, typ),
+          cCall(cgsymValue(p.module, "newObjRC1"),
             ti,
-            sizeExpr)
-        b.snippet = bres
+            sizeExpr))
         let ra = a.rdLoc
         let rb = b.rdLoc
         p.s(cpsStmts).addAssignment(ra, rb)
     else:
-      var bres = newBuilder("")
-      bres.addCast(getTypeDesc(p.module, typ)):
-        bres.addCall(cgsymValue(p.module, "newObj"),
+      b.snippet = cCast(getTypeDesc(p.module, typ),
+        cCall(cgsymValue(p.module, "newObj"),
           ti,
-          sizeExpr)
-      b.snippet = bres
+          sizeExpr))
       genAssignment(p, a, b, {})
   # set the object type:
   genObjectInit(p, cpsStmts, bt, a, constructRefObj)
@@ -1686,20 +1665,16 @@ proc genNewSeqAux(p: BProc, dest: TLoc, length: Rope; lenIsZero: bool) =
       let typinfo = genTypeInfoV1(p.module, seqtype, dest.lode.info)
       if p.config.selectedGC == gcGo:
         # we need the write barrier
-        var callRes = newBuilder("")
-        callRes.addCast(st):
-          callRes.addCall(cgsymValue(p.module, "newSeq"), typinfo, length)
-        call.snippet = callRes
+        call.snippet = cCast(st,
+          cCall(cgsymValue(p.module, "newSeq"), typinfo, length))
         let rad = addrLoc(p.config, dest)
         let rc = call.rdLoc
         p.s(cpsStmts).addCallStmt(cgsymValue(p.module, "unsureAsgnRef"),
           cCast("void**", rad),
           rc)
       else:
-        var callRes = newBuilder("")
-        callRes.addCast(st):
-          callRes.addCall(cgsymValue(p.module, "newSeqRC1"), typinfo, length)
-        call.snippet = callRes
+        call.snippet = cCast(st,
+          cCall(cgsymValue(p.module, "newSeqRC1"), typinfo, length))
         let rd = dest.rdLoc
         let rc = call.rdLoc
         p.s(cpsStmts).addAssignment(rd, rc)
@@ -1709,10 +1684,8 @@ proc genNewSeqAux(p: BProc, dest: TLoc, length: Rope; lenIsZero: bool) =
     else:
       let st = getTypeDesc(p.module, seqtype)
       let typinfo = genTypeInfoV1(p.module, seqtype, dest.lode.info)
-      var callRes = newBuilder("")
-      callRes.addCast(st):
-        callRes.addCall(cgsymValue(p.module, "newSeq"), typinfo, length)
-      call.snippet = callRes
+      call.snippet = cCast(st,
+        cCall(cgsymValue(p.module, "newSeq"), typinfo, length))
     genAssignment(p, dest, call, {})
 
 proc genNewSeq(p: BProc, e: PNode) =
@@ -1755,11 +1728,10 @@ proc genNewSeqOfCap(p: BProc; e: PNode; d: var TLoc) =
   else:
     if d.k == locNone: d = getTemp(p, e.typ, needsInit=false) # bug #22560
     let ra = a.rdLoc
-    var dres = newBuilder("")
-    dres.addCast(getTypeDesc(p.module, seqtype)):
-      dres.addCall(cgsymValue(p.module, "nimNewSeqOfCap"),
+    let dres = cCast(getTypeDesc(p.module, seqtype),
+      cCall(cgsymValue(p.module, "nimNewSeqOfCap"),
         genTypeInfoV1(p.module, seqtype, e.info),
-        ra)
+        ra))
     putIntoDest(p, d, e, dres)
     gcUsage(p.config, e)
 
@@ -1771,15 +1743,14 @@ proc rawConstExpr(p: BProc, n: PNode; d: var TLoc) =
   if id == p.module.labels:
     # expression not found in the cache:
     inc(p.module.labels)
+    let td = getTypeDesc(p.module, t)
     var data = newBuilder("")
-    data.addVarWithTypeAndInitializer(kind = Const, name = d.snippet):
-      data.add(getTypeDesc(p.module, t))
-    do:
+    data.addVarWithInitializer(kind = Const, name = d.snippet, typ = td):
       # bug #23627; when generating const object fields, it's likely that
       # we need to generate type infos for the object, which may be an object with
       # custom hooks. We need to generate potential consts in the hooks first.
       genBracedInit(p, n, isConst = true, t, data)
-    p.module.s[cfsData].add data
+    p.module.s[cfsData].add(extract(data))
 
 proc handleConstExpr(p: BProc, n: PNode, d: var TLoc): bool =
   if d.k == locNone and n.len > ord(n.kind == nkObjConstr) and n.isDeepConstExpr:
@@ -1942,8 +1913,7 @@ proc genArrToSeq(p: BProc, n: PNode, d: var TLoc) =
   if L < 10:
     for i in 0..<L:
       elem = initLoc(locExpr, lodeTyp elemType(skipTypes(n.typ, abstractInst)), OnHeap)
-      var lit = newRopeAppender()
-      intLiteral(i, lit)
+      let lit = cIntLiteral(i)
       elem.snippet = ropecg(p.module, "$1$3[$2]", [rdLoc(d), lit, dataField(p)])
       elem.storage = OnHeap # we know that sequences are on the heap
       arr = initLoc(locExpr, lodeTyp elemType(skipTypes(n[1].typ, abstractInst)), a.storage)
@@ -2518,12 +2488,12 @@ proc genRangeChck(p: BProc, n: PNode, d: var TLoc) =
 
     # emit range check:
     if n0t.kind in {tyUInt, tyUInt64}:
-      var first = newRopeAppender()
+      var first = newBuilder("")
       genLiteral(p, n[1], dest, first)
-      var last = newRopeAppender()
+      var last = newBuilder("")
       genLiteral(p, n[2], dest, last)
       linefmt(p, cpsStmts, "if ($1 > ($5)($3)){ #raiseRangeErrorNoArgs(); ",
-        [rdCharLoc(a), first, last,
+        [rdCharLoc(a), extract(first), extract(last),
         raiser, getTypeDesc(p.module, n0t)])
       raiseInstr(p, p.s(cpsStmts))
       linefmt p, cpsStmts, "}$n", []
@@ -2541,12 +2511,12 @@ proc genRangeChck(p: BProc, n: PNode, d: var TLoc) =
           "(NI64)"
         else:
           ""
-      var first = newRopeAppender()
+      var first = newBuilder("")
       genLiteral(p, n[1], dest, first)
-      var last = newRopeAppender()
+      var last = newBuilder("")
       genLiteral(p, n[2], dest, last)
       linefmt(p, cpsStmts, "if ($5($1) < $2 || $5($1) > $3){ $4($1, $2, $3); ",
-        [rdCharLoc(a), first, last,
+        [rdCharLoc(a), extract(first), extract(last),
         raiser, boundaryCast])
       raiseInstr(p, p.s(cpsStmts))
       linefmt p, cpsStmts, "}$n", []
@@ -2952,9 +2922,9 @@ proc genSetConstr(p: BProc, e: PNode, d: var TLoc) =
     a, b: TLoc
   var idx: TLoc
   if nfAllConst in e.flags:
-    var elem = newRopeAppender()
+    var elem = newBuilder("")
     genSetNode(p, e, elem)
-    putIntoDest(p, d, e, elem)
+    putIntoDest(p, d, e, extract(elem))
   else:
     if d.k == locNone: d = getTemp(p, e.typ)
     if getSize(p.config, e.typ) > 8:
@@ -3043,12 +3013,11 @@ proc genClosure(p: BProc, n: PNode, d: var TLoc) =
   if isConstClosure(n):
     inc(p.module.labels)
     var tmp = "CNSTCLOSURE" & rope(p.module.labels)
+    let td = getTypeDesc(p.module, n.typ)
     var data = newBuilder("")
-    data.addVarWithTypeAndInitializer(kind = Const, name = tmp):
-      data.add(getTypeDesc(p.module, n.typ))
-    do:
+    data.addVarWithInitializer(kind = Const, name = tmp, typ = td):
       genBracedInit(p, n, isConst = true, n.typ, data)
-    p.module.s[cfsData].add data
+    p.module.s[cfsData].add(extract(data))
     putIntoDest(p, d, n, tmp, OnStatic)
   else:
     var tmp: TLoc
@@ -3075,8 +3044,7 @@ proc genArrayConstr(p: BProc, n: PNode, d: var TLoc) =
     if d.k == locNone: d = getTemp(p, n.typ)
     for i in 0..<n.len:
       arr = initLoc(locExpr, lodeTyp elemType(skipTypes(n.typ, abstractInst)), d.storage)
-      var lit = newRopeAppender()
-      intLiteral(i, lit)
+      let lit = cIntLiteral(i)
       arr.snippet = subscript(rdLoc(d), lit)
       expr(p, n[i], arr)
 
@@ -3215,11 +3183,12 @@ proc exprComplexConst(p: BProc, n: PNode, d: var TLoc) =
   if id == p.module.labels:
     # expression not found in the cache:
     inc(p.module.labels)
-    p.module.s[cfsData].addVarWithTypeAndInitializer(
-        kind = Const, name = tmp):
-      p.module.s[cfsData].add(getTypeDesc(p.module, t, dkConst))
-    do:
-      genBracedInit(p, n, isConst = true, t, p.module.s[cfsData])
+    let td = getTypeDesc(p.module, t, dkConst)
+    var data = newBuilder("")
+    data.addVarWithInitializer(
+        kind = Const, name = tmp, typ = td):
+      genBracedInit(p, n, isConst = true, t, data)
+    p.module.s[cfsData].add(extract(data))
 
   if d.k == locNone:
     fillLoc(d, locData, n, tmp, OnStatic)
@@ -3258,20 +3227,19 @@ proc genConstHeader(m, q: BModule; p: BProc, sym: PSym) =
     headerDecl.addDeclWithVisibility(Extern):
       headerDecl.addVar(kind = Local, name = sym.loc.snippet,
         typ = constType(getTypeDesc(m, sym.loc.t, dkVar)))
-    m.s[cfsData].add(headerDecl)
+    m.s[cfsData].add(extract(headerDecl))
     if sfExportc in sym.flags and p.module.g.generatedHeader != nil:
-      p.module.g.generatedHeader.s[cfsData].add(headerDecl)
+      p.module.g.generatedHeader.s[cfsData].add(extract(headerDecl))
 
 proc genConstDefinition(q: BModule; p: BProc; sym: PSym) =
   # add a suffix for hcr - will later init the global pointer with this data
   let actualConstName = if q.hcrOn: sym.loc.snippet & "_const" else: sym.loc.snippet
-  var data = newRopeAppender()
+  let td = constType(getTypeDesc(q, sym.typ))
+  var data = newBuilder("")
   data.addDeclWithVisibility(Private):
-    data.addVarWithTypeAndInitializer(Local, actualConstName):
-      data.add(constType(getTypeDesc(q, sym.typ)))
-    do:
+    data.addVarWithInitializer(Local, actualConstName, typ = td):
       genBracedInit(q.initProc, sym.astdef, isConst = true, sym.typ, data)
-  q.s[cfsData].add data
+  q.s[cfsData].add(extract(data))
   if q.hcrOn:
     # generate the global pointer with the real name
     q.s[cfsVars].addVar(kind = Global, name = sym.loc.snippet,
@@ -3348,9 +3316,9 @@ proc expr(p: BProc, n: PNode, d: var TLoc) =
       putLocIntoDest(p, d, sym.loc)
     of skConst:
       if isSimpleConst(sym.typ):
-        var lit = newRopeAppender()
+        var lit = newBuilder("")
         genLiteral(p, sym.astdef, sym.typ, lit)
-        putIntoDest(p, d, n, lit, OnStatic)
+        putIntoDest(p, d, n, extract(lit), OnStatic)
       elif useAliveDataFromDce in p.module.flags:
         genConstHeader(p.module, p.module, p, sym)
         assert((sym.loc.snippet != "") and (sym.loc.t != nil))
@@ -3402,17 +3370,17 @@ proc expr(p: BProc, n: PNode, d: var TLoc) =
     else: internalError(p.config, n.info, "expr(" & $sym.kind & "); unknown symbol")
   of nkNilLit:
     if not isEmptyType(n.typ):
-      var lit = newRopeAppender()
+      var lit = newBuilder("")
       genLiteral(p, n, lit)
-      putIntoDest(p, d, n, lit)
+      putIntoDest(p, d, n, extract(lit))
   of nkStrLit..nkTripleStrLit:
-    var lit = newRopeAppender()
+    var lit = newBuilder("")
     genLiteral(p, n, lit)
-    putDataIntoDest(p, d, n, lit)
+    putDataIntoDest(p, d, n, extract(lit))
   of nkIntLit..nkUInt64Lit, nkFloatLit..nkFloat128Lit, nkCharLit:
-    var lit = newRopeAppender()
+    var lit = newBuilder("")
     genLiteral(p, n, lit)
-    putIntoDest(p, d, n, lit)
+    putIntoDest(p, d, n, extract(lit))
   of nkCall, nkHiddenCallConv, nkInfix, nkPrefix, nkPostfix, nkCommand,
      nkCallStrLit:
     genLineDir(p, n) # may be redundant, it is generated in fixupCall as well
@@ -3432,9 +3400,9 @@ proc expr(p: BProc, n: PNode, d: var TLoc) =
         genCall(p, n, d)
   of nkCurly:
     if isDeepConstExpr(n) and n.len != 0:
-      var lit = newRopeAppender()
+      var lit = newBuilder("")
       genSetNode(p, n, lit)
-      putIntoDest(p, d, n, lit)
+      putIntoDest(p, d, n, extract(lit))
     else:
       genSetConstr(p, n, d)
   of nkBracket:
@@ -3781,6 +3749,7 @@ proc genConstSeq(p: BProc, n: PNode, t: PType; isConst: bool; result: var Builde
   let base = t.skipTypes(abstractInst)[0]
   let tmpName = getTempName(p.module)
 
+  # genBracedInit can modify cfsStrData, we need an intermediate builder:
   var def = newBuilder("")
   def.addVarWithTypeAndInitializer(
       if isConst: Const else: Global,
@@ -3805,7 +3774,7 @@ proc genConstSeq(p: BProc, n: PNode, t: PType; isConst: bool; result: var Builde
             for i in 0..<n.len:
               def.addField(arrInit, name = ""):
                 genBracedInit(p, n[i], isConst, base, def)
-  p.module.s[cfsStrData].add def
+  p.module.s[cfsStrData].add extract(def)
 
   result.add cCast(typ = getTypeDesc(p.module, t), value = cAddr(tmpName))
 
@@ -3813,6 +3782,7 @@ proc genConstSeqV2(p: BProc, n: PNode, t: PType; isConst: bool; result: var Buil
   let base = t.skipTypes(abstractInst)[0]
   let payload = getTempName(p.module)
 
+  # genBracedInit can modify cfsStrData, we need an intermediate builder:
   var def = newBuilder("")
   def.addVarWithTypeAndInitializer(
       if isConst: AlwaysConst else: Global,
@@ -3832,7 +3802,7 @@ proc genConstSeqV2(p: BProc, n: PNode, t: PType; isConst: bool; result: var Buil
             for i in 0..<n.len:
               def.addField(arrInit, name = ""):
                 genBracedInit(p, n[i], isConst, base, def)
-  p.module.s[cfsStrData].add def
+  p.module.s[cfsStrData].add extract(def)
 
   var resultInit: StructInitializer
   result.addStructInitializer(resultInit, kind = siOrderedStruct):
@@ -3900,12 +3870,13 @@ proc genBracedInit(p: BProc, n: PNode; isConst: bool; optionalType: PType; resul
       let payload = getTempName(p.module)
       let ctype = getTypeDesc(p.module, typ.elementType)
       let arrLen = n.len
+      # genConstSimpleList can modify cfsStrData, we need an intermediate builder:
       var data = newBuilder("")
       data.addArrayVarWithInitializer(
           kind = if isConst: AlwaysConst else: Global,
           name = payload, elementType = ctype, len = arrLen):
         genConstSimpleList(p, n, isConst, data)
-      p.module.s[cfsStrData].add(data)
+      p.module.s[cfsStrData].add(extract(data))
       var openArrInit: StructInitializer
       result.addStructInitializer(openArrInit, kind = siOrderedStruct):
         result.addField(openArrInit, name = "Field0"):
diff --git a/compiler/ccgliterals.nim b/compiler/ccgliterals.nim
index 477e0bf85041..7d72e27b3424 100644
--- a/compiler/ccgliterals.nim
+++ b/compiler/ccgliterals.nim
@@ -53,9 +53,9 @@ proc genStringLiteralDataOnlyV1(m: BModule, s: string; result: var Rope) =
             res.add(cCast("NI", bitOr(cCast("NU", rope(s.len)), "NIM_STRLIT_FLAG")))
       res.addField(strInit, name = "data"):
         res.add(makeCString(s))
-  m.s[cfsStrData].add(res)
+  m.s[cfsStrData].add(extract(res))
 
-proc genStringLiteralV1(m: BModule; n: PNode; result: var Rope) =
+proc genStringLiteralV1(m: BModule; n: PNode; result: var Builder) =
   if s.isNil:
     result.add(cCast(ptrType(cgsymValue(m, "NimStringDesc")), "NIM_NIL"))
   else:
@@ -85,9 +85,9 @@ proc genStringLiteralDataOnlyV2(m: BModule, s: string; result: Rope; isConst: bo
         res.add(bitOr(rope(s.len), "NIM_STRLIT_FLAG"))
       res.addField(structInit, name = "data"):
         res.add(makeCString(s))
-  m.s[cfsStrData].add(res)
+  m.s[cfsStrData].add(extract(res))
 
-proc genStringLiteralV2(m: BModule; n: PNode; isConst: bool; result: var Rope) =
+proc genStringLiteralV2(m: BModule; n: PNode; isConst: bool; result: var Builder) =
   let id = nodeTableTestOrSet(m.dataCache, n, m.labels)
   var litName: string
   if id == m.labels:
@@ -101,20 +101,19 @@ proc genStringLiteralV2(m: BModule; n: PNode; isConst: bool; result: var Rope) =
   let tmp = getTempName(m)
   result.add tmp
   var res = newBuilder("")
-  res.addVarWithTypeAndInitializer(
+  res.addVarWithInitializer(
       if isConst: AlwaysConst else: Global,
-      name = tmp):
-    res.add("NimStringV2")
-  do:
+      name = tmp,
+      typ = "NimStringV2"):
     var strInit: StructInitializer
     res.addStructInitializer(strInit, kind = siOrderedStruct):
       res.addField(strInit, name = "len"):
         res.addIntValue(n.strVal.len)
       res.addField(strInit, name = "p"):
         res.add(cCast(ptrType("NimStrPayload"), cAddr(litName)))
-  m.s[cfsStrData].add(res)
+  m.s[cfsStrData].add(extract(res))
 
-proc genStringLiteralV2Const(m: BModule; n: PNode; isConst: bool; result: var Rope) =
+proc genStringLiteralV2Const(m: BModule; n: PNode; isConst: bool; result: var Builder) =
   let id = nodeTableTestOrSet(m.dataCache, n, m.labels)
   var pureLit: Rope
   if id == m.labels:
@@ -145,10 +144,10 @@ proc genStringLiteralDataOnly(m: BModule; s: string; info: TLineInfo;
   else:
     localError(m.config, info, "cannot determine how to produce code for string literal")
 
-proc genNilStringLiteral(m: BModule; info: TLineInfo; result: var Rope) =
+proc genNilStringLiteral(m: BModule; info: TLineInfo; result: var Builder) =
   result.add(cCast(ptrType(cgsymValue(m, "NimStringDesc")), "NIM_NIL"))
 
-proc genStringLiteral(m: BModule; n: PNode; result: var Rope) =
+proc genStringLiteral(m: BModule; n: PNode; result: var Builder) =
   case detectStrVersion(m)
   of 0, 1: genStringLiteralV1(m, n, result)
   of 2: genStringLiteralV2(m, n, isConst = true, result)
diff --git a/compiler/ccgstmts.nim b/compiler/ccgstmts.nim
index 5c71086df06c..9ccd4ccb65ac 100644
--- a/compiler/ccgstmts.nim
+++ b/compiler/ccgstmts.nim
@@ -146,16 +146,16 @@ proc loadInto(p: BProc, le, ri: PNode, a: var TLoc) {.inline.} =
     a.flags.incl(lfEnforceDeref)
     expr(p, ri, a)
 
-proc assignLabel(b: var TBlock; result: var Rope) {.inline.} =
+proc assignLabel(b: var TBlock; result: var Builder) {.inline.} =
   b.label = "LA" & b.id.rope
   result.add b.label
 
-proc blockBody(b: var TBlock; result: var Rope) =
-  result.add b.sections[cpsLocals]
+proc blockBody(b: var TBlock; result: var Builder) =
+  result.add extract(b.sections[cpsLocals])
   if b.frameLen > 0:
     result.addf("FR_.len+=$1;$n", [b.frameLen.rope])
-  result.add(b.sections[cpsInit])
-  result.add(b.sections[cpsStmts])
+  result.add(extract(b.sections[cpsInit]))
+  result.add(extract(b.sections[cpsStmts]))
 
 proc endBlock(p: BProc, blockEnd: Rope) =
   let topBlock = p.blocks.len-1
@@ -281,7 +281,7 @@ proc genGotoVar(p: BProc; value: PNode) =
 
 proc genBracedInit(p: BProc, n: PNode; isConst: bool; optionalType: PType; result: var Builder)
 
-proc potentialValueInit(p: BProc; v: PSym; value: PNode; result: var Rope) =
+proc potentialValueInit(p: BProc; v: PSym; value: PNode; result: var Builder) =
   if lfDynamicLib in v.loc.flags or sfThread in v.flags or p.hcrOn:
     discard "nothing to do"
   elif sfGlobal in v.flags and value != nil and isDeepConstExpr(value, p.module.compileToCpp) and
@@ -330,8 +330,9 @@ proc genSingleVar(p: BProc, v: PSym; vn, value: PNode) =
     value.kind in nkCallKinds and value[0].kind == nkSym and
     v.typ.kind != tyPtr and sfConstructor in value[0].sym.flags
   var targetProc = p
-  var valueAsRope = ""
-  potentialValueInit(p, v, value, valueAsRope)
+  var valueBuilder = newBuilder("")
+  potentialValueInit(p, v, value, valueBuilder)
+  let valueAsRope = extract(valueBuilder)
   if sfGlobal in v.flags:
     if v.flags * {sfImportc, sfExportc} == {sfImportc} and
         value.kind == nkEmpty and
@@ -594,8 +595,7 @@ proc genComputedGoto(p: BProc; n: PNode) =
         return
 
       let val = getOrdValue(it[j])
-      var lit = newRopeAppender()
-      intLiteral(toInt64(val)+id+1, lit)
+      let lit = cIntLiteral(toInt64(val)+id+1)
       lineF(p, cpsStmts, "TMP$#_:$n", [lit])
 
     genStmts(p, it.lastSon)
@@ -775,7 +775,7 @@ proc finallyActions(p: BProc) =
     if finallyBlock != nil:
       genSimpleBlock(p, finallyBlock[0])
 
-proc raiseInstr(p: BProc; result: var Rope) =
+proc raiseInstr(p: BProc; result: var Builder) =
   if p.config.exc == excGoto:
     let L = p.nestedTryStmts.len
     if L == 0:
@@ -925,8 +925,7 @@ proc genStringCase(p: BProc, t: PNode, stringKind: TTypeKind, d: var TLoc) =
               [rdLoc(a), bitMask])
     for j in 0..high(branches):
       if branches[j] != "":
-        var lit = newRopeAppender()
-        intLiteral(j, lit)
+        let lit = cIntLiteral(j)
         lineF(p, cpsStmts, "case $1: $n$2break;$n",
              [lit, branches[j]])
     lineF(p, cpsStmts, "}$n", []) # else statement:
@@ -964,22 +963,22 @@ proc genCaseRange(p: BProc, branch: PNode) =
   for j in 0..<branch.len-1:
     if branch[j].kind == nkRange:
       if hasSwitchRange in CC[p.config.cCompiler].props:
-        var litA = newRopeAppender()
-        var litB = newRopeAppender()
+        var litA = newBuilder("")
+        var litB = newBuilder("")
         genLiteral(p, branch[j][0], litA)
         genLiteral(p, branch[j][1], litB)
-        lineF(p, cpsStmts, "case $1 ... $2:$n", [litA, litB])
+        lineF(p, cpsStmts, "case $1 ... $2:$n", [extract(litA), extract(litB)])
       else:
         var v = copyNode(branch[j][0])
         while v.intVal <= branch[j][1].intVal:
-          var litA = newRopeAppender()
+          var litA = newBuilder("")
           genLiteral(p, v, litA)
-          lineF(p, cpsStmts, "case $1:$n", [litA])
+          lineF(p, cpsStmts, "case $1:$n", [extract(litA)])
           inc(v.intVal)
     else:
-      var litA = newRopeAppender()
+      var litA = newBuilder("")
       genLiteral(p, branch[j], litA)
-      lineF(p, cpsStmts, "case $1:$n", [litA])
+      lineF(p, cpsStmts, "case $1:$n", [extract(litA)])
 
 proc genOrdinalCase(p: BProc, n: PNode, d: var TLoc) =
   # analyse 'case' statement:
@@ -1641,8 +1640,7 @@ proc genDiscriminantCheck(p: BProc, a, tmp: TLoc, objtype: PType,
   if not containsOrIncl(p.module.declaredThings, field.id):
     appcg(p.module, cfsVars, "extern $1",
           [discriminatorTableDecl(p.module, t, field)])
-  var lit = newRopeAppender()
-  intLiteral(toInt64(lengthOrd(p.config, field.typ))+1, lit)
+  let lit = cIntLiteral(toInt64(lengthOrd(p.config, field.typ))+1)
   lineCg(p, cpsStmts,
         "#FieldDiscriminantCheck((NI)(NU)($1), (NI)(NU)($2), $3, $4);$n",
         [rdLoc(a), rdLoc(tmp), discriminatorTableName(p.module, t, field),
diff --git a/compiler/ccgthreadvars.nim b/compiler/ccgthreadvars.nim
index 46ebded49b39..5ccc1a524bf0 100644
--- a/compiler/ccgthreadvars.nim
+++ b/compiler/ccgthreadvars.nim
@@ -47,11 +47,9 @@ proc generateThreadLocalStorage(m: BModule) =
   if m.g.nimtv != "" and (usesThreadVars in m.flags or sfMainModule in m.module.flags):
     for t in items(m.g.nimtvDeps): discard getTypeDesc(m, t)
     finishTypeDescriptions(m)
-    var typedef = newBuilder("")
-    typedef.addTypedef(name = "NimThreadVars"):
-      typedef.addSimpleStruct(m, name = "", baseType = ""):
-        typedef.add(m.g.nimtv)
-    m.s[cfsSeqTypes].add(typedef)
+    m.s[cfsSeqTypes].addTypedef(name = "NimThreadVars"):
+      m.s[cfsSeqTypes].addSimpleStruct(m, name = "", baseType = ""):
+        m.s[cfsSeqTypes].add(m.g.nimtv)
 
 proc generateThreadVarsSize(m: BModule) =
   if m.g.nimtv != "":
diff --git a/compiler/ccgtrav.nim b/compiler/ccgtrav.nim
index ed4c79d9a50b..6ca65956cb45 100644
--- a/compiler/ccgtrav.nim
+++ b/compiler/ccgtrav.nim
@@ -76,12 +76,11 @@ proc genTraverseProc(c: TTraversalClosure, accessor: Rope, typ: PType) =
     let arraySize = lengthOrd(c.p.config, typ.indexType)
     var i: TLoc = getTemp(p, getSysType(c.p.module.g.graph, unknownLineInfo, tyInt))
     var oldCode = p.s(cpsStmts)
-    freeze oldCode
     linefmt(p, cpsStmts, "for ($1 = 0; $1 < $2; $1++) {$n",
             [i.snippet, arraySize])
-    let oldLen = p.s(cpsStmts).len
+    let oldLen = p.s(cpsStmts).buf.len
     genTraverseProc(c, ropecg(c.p.module, "$1[$2]", [accessor, i.snippet]), typ.elementType)
-    if p.s(cpsStmts).len == oldLen:
+    if p.s(cpsStmts).buf.len == oldLen:
       # do not emit dummy long loops for faster debug builds:
       p.s(cpsStmts) = oldCode
     else:
@@ -119,14 +118,13 @@ proc genTraverseProcSeq(c: TTraversalClosure, accessor: Rope, typ: PType) =
   assert typ.kind == tySequence
   var i = getTemp(p, getSysType(c.p.module.g.graph, unknownLineInfo, tyInt))
   var oldCode = p.s(cpsStmts)
-  freeze oldCode
   var a = TLoc(snippet: accessor)
 
   lineF(p, cpsStmts, "for ($1 = 0; $1 < $2; $1++) {$n",
       [i.snippet, lenExpr(c.p, a)])
-  let oldLen = p.s(cpsStmts).len
+  let oldLen = p.s(cpsStmts).buf.len
   genTraverseProc(c, "$1$3[$2]" % [accessor, i.snippet, dataField(c.p)], typ.elementType)
-  if p.s(cpsStmts).len == oldLen:
+  if p.s(cpsStmts).buf.len == oldLen:
     # do not emit dummy long loops for faster debug builds:
     p.s(cpsStmts) = oldCode
   else:
@@ -160,7 +158,7 @@ proc genTraverseProc(m: BModule, origTyp: PType; sig: SigHash): Rope =
       genTraverseProc(c, "(*a)".rope, typ.elementType)
 
   let generatedProc = "$1 {$n$2$3$4}\n" %
-        [header, p.s(cpsLocals), p.s(cpsInit), p.s(cpsStmts)]
+        [header, extract(p.s(cpsLocals)), extract(p.s(cpsInit)), extract(p.s(cpsStmts))]
 
   m.s[cfsProcHeaders].addf("$1;\n", [header])
   m.s[cfsProcs].add(generatedProc)
@@ -189,7 +187,7 @@ proc genTraverseProcForGlobal(m: BModule, s: PSym; info: TLineInfo): Rope =
   genTraverseProc(c, sLoc, s.loc.t)
 
   let generatedProc = "$1 {$n$2$3$4}$n" %
-        [header, p.s(cpsLocals), p.s(cpsInit), p.s(cpsStmts)]
+        [header, extract(p.s(cpsLocals)), extract(p.s(cpsInit)), extract(p.s(cpsStmts))]
 
   m.s[cfsProcHeaders].addf("$1;$n", [header])
   m.s[cfsProcs].add(generatedProc)
diff --git a/compiler/ccgtypes.nim b/compiler/ccgtypes.nim
index a3c3c2a85005..04b740aa92d9 100644
--- a/compiler/ccgtypes.nim
+++ b/compiler/ccgtypes.nim
@@ -427,11 +427,9 @@ proc getTypeDescWeak(m: BModule; t: PType; check: var IntSet; kind: TypeDescKind
       if cacheGetType(m.typeCache, sig) == "":
         m.typeCache[sig] = result
         #echo "adding ", sig, " ", typeToString(t), " ", m.module.name.s
-        var struct = newBuilder("")
-        struct.addSimpleStruct(m, name = result, baseType = ""):
-          struct.addField(name = "len", typ = "NI")
-          struct.addField(name = "p", typ = ptrType(result & "_Content"))
-        m.s[cfsTypes].add(struct)
+        m.s[cfsTypes].addSimpleStruct(m, name = result, baseType = ""):
+          m.s[cfsTypes].addField(name = "len", typ = "NI")
+          m.s[cfsTypes].addField(name = "p", typ = ptrType(result & "_Content"))
         pushType(m, t)
     else:
       result = getTypeForward(m, t, sig) & seqStar(m)
@@ -450,13 +448,12 @@ proc seqV2ContentType(m: BModule; t: PType; check: var IntSet) =
   if result == "":
     discard getTypeDescAux(m, t, check, dkVar)
   else:
-    var struct = newBuilder("")
-    struct.addSimpleStruct(m, name = result & "_Content", baseType = ""):
-      struct.addField(name = "cap", typ = "NI")
-      struct.addField(name = "data",
-        typ = getTypeDescAux(m, t.skipTypes(abstractInst)[0], check, dkVar),
+    let dataTyp = getTypeDescAux(m, t.skipTypes(abstractInst)[0], check, dkVar)
+    m.s[cfsTypes].addSimpleStruct(m, name = result & "_Content", baseType = ""):
+      m.s[cfsTypes].addField(name = "cap", typ = "NI")
+      m.s[cfsTypes].addField(name = "data",
+        typ = dataTyp,
         isFlexArray = true)
-    m.s[cfsTypes].add(struct)
 
 proc paramStorageLoc(param: PSym): TStorageLoc =
   if param.typ.skipTypes({tyVar, tyLent, tyTypeDesc}).kind notin {
@@ -685,7 +682,7 @@ proc genRecordFieldsAux(m: BModule; n: PNode,
     genRecordFieldsAux(m, n[0], rectype, check, result, unionPrefix)
     # prefix mangled name with "_U" to avoid clashes with other field names,
     # since identifiers are not allowed to start with '_'
-    var unionBody: Rope = ""
+    var unionBody = newBuilder("")
     for i in 1..<n.len:
       case n[i].kind
       of nkOfBranch, nkElse:
@@ -694,16 +691,16 @@ proc genRecordFieldsAux(m: BModule; n: PNode,
           let structName = "_" & mangleRecFieldName(m, n[0].sym) & "_" & $i
           var a = newBuilder("")
           genRecordFieldsAux(m, k, rectype, check, a, unionPrefix & $structName & ".")
-          if a.len != 0:
+          if a.buf.len != 0:
             unionBody.addFieldWithStructType(m, rectype, structName):
-              unionBody.add(a)
+              unionBody.add(extract(a))
         else:
           genRecordFieldsAux(m, k, rectype, check, unionBody, unionPrefix)
       else: internalError(m.config, "genRecordFieldsAux(record case branch)")
-    if unionBody.len != 0:
+    if unionBody.buf.len != 0:
       result.addAnonUnion:
         # XXX this has to be a named field for NIFC
-        result.add(unionBody)
+        result.add(extract(unionBody))
   of nkSym:
     let field = n.sym
     if field.typ.kind == tyVoid: return
@@ -735,7 +732,7 @@ proc genRecordFieldsAux(m: BModule; n: PNode,
       result.addField(field, sname, typ, isFlexArray, initializer)
   else: internalError(m.config, n.info, "genRecordFieldsAux()")
 
-proc genMemberProcHeader(m: BModule; prc: PSym; result: var Rope; asPtr: bool = false, isFwdDecl:bool = false)
+proc genMemberProcHeader(m: BModule; prc: PSym; result: var Builder; asPtr: bool = false, isFwdDecl:bool = false)
 
 proc addRecordFields(result: var Builder; m: BModule; typ: PType, check: var IntSet) =
   genRecordFieldsAux(m, typ.n, typ, check, result)
@@ -743,14 +740,15 @@ proc addRecordFields(result: var Builder; m: BModule; typ: PType, check: var Int
     let procs = m.g.graph.memberProcsPerType[typ.itemId]
     var isDefaultCtorGen, isCtorGen: bool = false
     for prc in procs:
-      var header: Rope = ""
       if sfConstructor in prc.flags:
         isCtorGen = true
         if prc.typ.n.len == 1:
           isDefaultCtorGen = true
       if lfNoDecl in prc.loc.flags: continue
+      var header = newBuilder("")
       genMemberProcHeader(m, prc, header, false, true)
-      result.addf "$1;$n", [header]
+      result.addStmt():
+        result.add(extract(header))
     if isCtorGen and not isDefaultCtorGen:
       var ch: IntSet = default(IntSet)
       result.addf "$1() = default;$n", [getTypeDescAux(m, typ, ch, dkOther)]
@@ -771,22 +769,24 @@ proc getRecordDesc(m: BModule; typ: PType, name: Rope,
   if typ.baseClass != nil:
     baseType = getTypeDescAux(m, typ.baseClass.skipTypes(skipPtrs), check, dkField)
   if typ.sym == nil or sfCodegenDecl notin typ.sym.flags:
-    result = newBuilder("")
-    result.addStruct(m, typ, name, baseType):
-      result.addRecordFields(m, typ, check)
+    var res = newBuilder("")
+    res.addStruct(m, typ, name, baseType):
+      res.addRecordFields(m, typ, check)
+    result = extract(res)
   else:
     var desc = newBuilder("")
     desc.addRecordFields(m, typ, check)
-    result = runtimeFormat(typ.sym.cgDeclFrmt, [name, desc, baseType])
+    result = runtimeFormat(typ.sym.cgDeclFrmt, [name, extract(desc), baseType])
 
 proc getTupleDesc(m: BModule; typ: PType, name: Rope,
                   check: var IntSet): Rope =
-  result = newBuilder("")
-  result.addStruct(m, typ, name, ""):
+  var res = newBuilder("")
+  res.addStruct(m, typ, name, ""):
     for i, a in typ.ikids:
-      result.addField(
+      res.addField(
         name = "Field" & $i,
         typ = getTypeDescAux(m, a, check, dkField))
+  result = extract(res)
 
 proc scanCppGenericSlot(pat: string, cursor, outIdx, outStars: var int): bool =
   # A helper proc for handling cppimport patterns, involving numeric
@@ -827,12 +827,10 @@ proc getOpenArrayDesc(m: BModule; t: PType, check: var IntSet; kind: TypeDescKin
       result = getTypeName(m, t, sig)
       m.typeCache[sig] = result
       let elemType = getTypeDescWeak(m, t.elementType, check, kind)
-      var typedef = newBuilder("")
-      typedef.addTypedef(name = result):
-        typedef.addSimpleStruct(m, name = "", baseType = ""):
-          typedef.addField(name = "Field0", typ = ptrType(elemType))
-          typedef.addField(name = "Field1", typ = "NI")
-      m.s[cfsTypes].add(typedef)
+      m.s[cfsTypes].addTypedef(name = result):
+        m.s[cfsTypes].addSimpleStruct(m, name = "", baseType = ""):
+          m.s[cfsTypes].addField(name = "Field0", typ = ptrType(elemType))
+          m.s[cfsTypes].addField(name = "Field1", typ = "NI")
 
 proc getTypeDescAux(m: BModule; origTyp: PType, check: var IntSet; kind: TypeDescKind): Rope =
   # returns only the type's name
@@ -904,28 +902,26 @@ proc getTypeDescAux(m: BModule; origTyp: PType, check: var IntSet; kind: TypeDes
           (sfImportc in t.sym.flags and t.sym.magic == mNone)):
         m.typeCache[sig] = result
         var size: int
-        var typedef = newBuilder("")
         if firstOrd(m.config, t) < 0:
-          typedef.addTypedef(name = result):
-            typedef.add("NI32")
+          m.s[cfsTypes].addTypedef(name = result):
+            m.s[cfsTypes].add("NI32")
           size = 4
         else:
           size = int(getSize(m.config, t))
           case size
           of 1:
-            typedef.addTypedef(name = result):
-              typedef.add("NU8")
+            m.s[cfsTypes].addTypedef(name = result):
+              m.s[cfsTypes].add("NU8")
           of 2:
-            typedef.addTypedef(name = result):
-              typedef.add("NU16")
+            m.s[cfsTypes].addTypedef(name = result):
+              m.s[cfsTypes].add("NU16")
           of 4:
-            typedef.addTypedef(name = result):
-              typedef.add("NI32")
+            m.s[cfsTypes].addTypedef(name = result):
+              m.s[cfsTypes].add("NI32")
           of 8:
-            typedef.addTypedef(name = result):
-              typedef.add("NI64")
+            m.s[cfsTypes].addTypedef(name = result):
+              m.s[cfsTypes].add("NI64")
           else: internalError(m.config, t.sym.info, "getTypeDescAux: enum")
-        m.s[cfsTypes].add(typedef)
         when false:
           let owner = hashOwner(t.sym)
           if not gDebugInfo.hasEnum(t.sym.name.s, t.sym.info.line, owner):
@@ -942,16 +938,15 @@ proc getTypeDescAux(m: BModule; origTyp: PType, check: var IntSet; kind: TypeDes
     var rettype: Snippet = ""
     var desc = newBuilder("")
     genProcParams(m, t, rettype, desc, check, true, true)
+    let params = extract(desc)
     if not isImportedType(t):
-      var typedef = newBuilder("")
       if t.callConv != ccClosure: # procedure vars may need a closure!
-        typedef.addProcTypedef(callConv = t.callConv, name = result, rettype = rettype, params = desc)
+        m.s[cfsTypes].addProcTypedef(callConv = t.callConv, name = result, rettype = rettype, params = params)
       else:
-        typedef.addTypedef(name = result):
-          typedef.addSimpleStruct(m, name = "", baseType = ""):
-            typedef.addProcField(name = "ClP_0", callConv = ccNimCall, rettype = rettype, params = desc)
-            typedef.addField(name = "ClE_0", typ = "void*")
-      m.s[cfsTypes].add(typedef)
+        m.s[cfsTypes].addTypedef(name = result):
+          m.s[cfsTypes].addSimpleStruct(m, name = "", baseType = ""):
+            m.s[cfsTypes].addProcField(name = "ClP_0", callConv = ccNimCall, rettype = rettype, params = params)
+            m.s[cfsTypes].addField(name = "ClE_0", typ = "void*")
   of tySequence:
     if optSeqDestructors in m.config.globalOptions:
       result = getTypeDescWeak(m, t, check, kind)
@@ -968,14 +963,13 @@ proc getTypeDescAux(m: BModule; origTyp: PType, check: var IntSet; kind: TypeDes
       m.typeCache[sig] = result & seqStar(m)
       if not isImportedType(t):
         if skipTypes(t.elementType, typedescInst).kind != tyEmpty:
-          var struct = newBuilder("")
+          let et = getTypeDescAux(m, t.elementType, check, kind)
           let baseType = cgsymValue(m, "TGenericSeq")
-          struct.addSimpleStruct(m, name = result, baseType = baseType):
-            struct.addField(
+          m.s[cfsSeqTypes].addSimpleStruct(m, name = result, baseType = baseType):
+            m.s[cfsSeqTypes].addField(
               name = "data",
-              typ = getTypeDescAux(m, t.elementType, check, kind),
+              typ = et,
               isFlexArray = true)
-          m.s[cfsSeqTypes].add struct
         else:
           result = rope("TGenericSeq")
       result.add(seqStar(m))
@@ -983,11 +977,9 @@ proc getTypeDescAux(m: BModule; origTyp: PType, check: var IntSet; kind: TypeDes
     result = getTypeName(m, origTyp, sig)
     m.typeCache[sig] = result
     if not isImportedType(t):
-      let foo = getTypeDescAux(m, t.elementType, check, kind)
-      var typedef = newBuilder("")
-      typedef.addArrayTypedef(name = result, len = 1):
-        typedef.add(foo)
-      m.s[cfsTypes].add(typedef)
+      let et = getTypeDescAux(m, t.elementType, check, kind)
+      m.s[cfsTypes].addArrayTypedef(name = result, len = 1):
+        m.s[cfsTypes].add(et)
   of tyArray:
     var n: BiggestInt = toInt64(lengthOrd(m.config, t))
     if n <= 0: n = 1   # make an array of at least one element
@@ -995,10 +987,8 @@ proc getTypeDescAux(m: BModule; origTyp: PType, check: var IntSet; kind: TypeDes
     m.typeCache[sig] = result
     if not isImportedType(t):
       let e = getTypeDescAux(m, t.elementType, check, kind)
-      var typedef = newBuilder("")
-      typedef.addArrayTypedef(name = result, len = n):
-        typedef.add(e)
-      m.s[cfsTypes].add(typedef)
+      m.s[cfsTypes].addArrayTypedef(name = result, len = n):
+        m.s[cfsTypes].add(e)
   of tyObject, tyTuple:
     let tt = origTyp.skipTypes({tyDistinct})
     if isImportedCppType(t) and tt.kind == tyGenericInst:
@@ -1106,16 +1096,15 @@ proc getClosureType(m: BModule; t: PType, kind: TClosureTypeKind): Rope =
   var rettype: Snippet = ""
   var desc = newBuilder("")
   genProcParams(m, t, rettype, desc, check, declareEnvironment=kind != clHalf)
+  let params = extract(desc)
   if not isImportedType(t):
-    var typedef = newBuilder("")
     if t.callConv != ccClosure or kind != clFull:
-      typedef.addProcTypedef(callConv = t.callConv, name = result, rettype = rettype, params = desc)
+      m.s[cfsTypes].addProcTypedef(callConv = t.callConv, name = result, rettype = rettype, params = params)
     else:
-      typedef.addTypedef(name = result):
-        typedef.addSimpleStruct(m, name = "", baseType = ""):
-          typedef.addProcField(name = "ClP_0", callConv = ccNimCall, rettype = rettype, params = desc)
-          typedef.addField(name = "ClE_0", typ = "void*")
-    m.s[cfsTypes].add(typedef)
+      m.s[cfsTypes].addTypedef(name = result):
+        m.s[cfsTypes].addSimpleStruct(m, name = "", baseType = ""):
+          m.s[cfsTypes].addProcField(name = "ClP_0", callConv = ccNimCall, rettype = rettype, params = params)
+          m.s[cfsTypes].addField(name = "ClE_0", typ = "void*")
 
 proc finishTypeDescriptions(m: BModule) =
   var i = 0
@@ -1158,7 +1147,7 @@ proc parseVFunctionDecl(val: string; name, params, retType, superCall: var strin
 
   params = "(" & params & ")"
 
-proc genMemberProcHeader(m: BModule; prc: PSym; result: var Rope; asPtr: bool = false, isFwdDecl: bool = false) =
+proc genMemberProcHeader(m: BModule; prc: PSym; result: var Builder; asPtr: bool = false, isFwdDecl: bool = false) =
   assert sfCppMember * prc.flags != {}
   let isCtor = sfConstructor in prc.flags
   var check = initIntSet()
@@ -1206,14 +1195,15 @@ proc genMemberProcHeader(m: BModule; prc: PSym; result: var Rope; asPtr: bool =
         [rope(CallingConvToStr[prc.typ.callConv]), asPtrStr, rettype, name,
         params, fnConst, override, superCall])
 
-proc genProcHeader(m: BModule; prc: PSym; result: var Rope; visibility: var DeclVisibility, asPtr: bool, addAttributes: bool) =
+proc genProcHeader(m: BModule; prc: PSym; result: var Builder; visibility: var DeclVisibility, asPtr: bool, addAttributes: bool) =
   # using static is needed for inline procs
   var check = initIntSet()
   fillBackendName(m, prc)
   fillLoc(prc.loc, locProc, prc.ast[namePos], OnUnknown)
   var rettype: Snippet = ""
-  var params = newBuilder("")
-  genProcParams(m, prc.typ, rettype, params, check, true, false)
+  var desc = newBuilder("")
+  genProcParams(m, prc.typ, rettype, desc, check, true, false)
+  let params = extract(desc)
   # handle the 2 options for hotcodereloading codegen - function pointer
   # (instead of forward declaration) or header for function body with "_actual" postfix
   var name = prc.loc.snippet
@@ -1513,14 +1503,21 @@ proc genEnumInfo(m: BModule; typ: PType, name: Rope; info: TLineInfo) =
   m.s[cfsTypeInit1].addArrayVarWithInitializer(
       kind = Global,
       name = enumArray,
-      elementType = "char* NIM_CONST", # XXX maybe do this in `addVar`
+      elementType = constPtrType("char"),
       len = typ.n.len):
-    m.s[cfsTypeInit1].add(enumNames)
-  m.s[cfsTypeInit3].addf("for ($1 = 0; $1 < $2; $1++) {$n" &
-      "$3[$1+$4].kind = 1;$n" & "$3[$1+$4].offset = $1;$n" &
-      "$3[$1+$4].name = $5[$1];$n" & "$6[$1] = &$3[$1+$4];$n" & "}$n", [counter,
-      rope(typ.n.len), m.typeNodesName, rope(firstNimNode), enumArray, nodePtrs])
-  m.s[cfsTypeInit3].add(specialCases)
+    m.s[cfsTypeInit1].add(extract(enumNames))
+  m.s[cfsTypeInit3].addForRangeExclusive(i = counter,
+      start = cIntValue(0),
+      bound = cIntValue(typ.n.len)):
+    let nodeLoc = subscript(m.typeNodesName,
+      cOp(Add, "NI", counter, cIntValue(firstNimNode)))
+    m.s[cfsTypeInit3].addFieldAssignment(nodeLoc, "kind", cIntValue(1))
+    m.s[cfsTypeInit3].addFieldAssignment(nodeLoc, "offset", counter)
+    m.s[cfsTypeInit3].addFieldAssignment(nodeLoc, "name",
+      subscript(enumArray, counter))
+    m.s[cfsTypeInit3].addSubscriptAssignment(nodePtrs, counter,
+      cAddr(nodeLoc))
+  m.s[cfsTypeInit3].add(extract(specialCases))
   let n = getNimNode(m)
   m.s[cfsTypeInit3].addFieldAssignment(n, "len", typ.n.len)
   m.s[cfsTypeInit3].addFieldAssignment(n, "kind", 0)
@@ -1528,8 +1525,9 @@ proc genEnumInfo(m: BModule; typ: PType, name: Rope; info: TLineInfo) =
     cAddr(subscript(nodePtrs, cIntValue(0))))
   m.s[cfsTypeInit3].addFieldAssignment(tiNameForHcr(m, name), "node", cAddr(n))
   if hasHoles:
-    # 1 << 2 is {ntfEnumHole}
-    m.s[cfsTypeInit3].addf("$1.flags = 1<<2;$n", [tiNameForHcr(m, name)])
+    m.s[cfsTypeInit3].addFieldAssignment(tiNameForHcr(m, name), "flags",
+      # 1 << 2 is {ntfEnumHole}
+      cOp(Shl, "NU8", cIntValue(1), cIntValue(2)))
 
 proc genSetInfo(m: BModule; typ: PType, name: Rope; info: TLineInfo) =
   assert(typ.elementType != nil)
@@ -1555,10 +1553,11 @@ include ccgtrav
 
 proc genDeepCopyProc(m: BModule; s: PSym; result: Rope) =
   genProc(m, s)
-  var params = newBuilder("")
+  var desc = newBuilder("")
   var paramBuilder: ProcParamBuilder
-  params.addProcParams(paramBuilder):
-    params.addUnnamedParam(paramBuilder, typ = "void*")
+  desc.addProcParams(paramBuilder):
+    desc.addUnnamedParam(paramBuilder, typ = "void*")
+  let params = extract(desc)
   let pt = procPtrTypeUnnamedNimCall(rettype = "void*", params = params)
   m.s[cfsTypeInit3].addFieldAssignmentWithValue(result, "deepcopy"):
     m.s[cfsTypeInit3].add(cCast(pt, s.loc.snippet))
@@ -1643,7 +1642,7 @@ proc generateRttiDestructor(g: ModuleGraph; typ: PType; owner: PSym; kind: TType
   incl result.flags, sfFromGeneric
   incl result.flags, sfGeneratedOp
 
-proc genHook(m: BModule; t: PType; info: TLineInfo; op: TTypeAttachedOp; result: var Rope) =
+proc genHook(m: BModule; t: PType; info: TLineInfo; op: TTypeAttachedOp; result: var Builder) =
   let theProc = getAttachedOp(m.g.graph, t, op)
   if theProc != nil and not isTrivialProc(m.g.graph, theProc):
     # the prototype of a destructor is ``=destroy(x: var T)`` and that of a
@@ -1719,7 +1718,7 @@ proc genTypeInfoV2OldImpl(m: BModule; t, origType: PType, name: Rope; info: TLin
   var flags = 0
   if not canFormAcycle(m.g.graph, t): flags = flags or 1
 
-  var typeEntry = newRopeAppender()
+  var typeEntry = newBuilder("")
   typeEntry.addFieldAssignmentWithValue(name, "destructor"):
     typeEntry.addCast("void*"):
       genHook(m, t, info, attachedDestructor, typeEntry)
@@ -1771,7 +1770,7 @@ proc genTypeInfoV2OldImpl(m: BModule; t, origType: PType, name: Rope; info: TLin
       genProcPrototype(m, i)
     typeEntry.addFieldAssignment(name, "vTable", vTablePointerName)
 
-  m.s[cfsTypeInit3].add typeEntry
+  m.s[cfsTypeInit3].add extract(typeEntry)
 
   if t.kind == tyObject and t.baseClass != nil and optEnableDeepCopy in m.config.globalOptions:
     discard genTypeInfoV1(m, t, info)
@@ -1784,11 +1783,9 @@ proc genTypeInfoV2Impl(m: BModule; t, origType: PType, name: Rope; info: TLineIn
   var flags = 0
   if not canFormAcycle(m.g.graph, t): flags = flags or 1
 
-  var typeEntry = newRopeAppender()
+  var typeEntry = newBuilder("")
   typeEntry.addDeclWithVisibility(Private):
-    typeEntry.addVarWithTypeAndInitializer(kind = Local, name = name):
-      typeEntry.add("TNimTypeV2")
-    do:
+    typeEntry.addVarWithInitializer(kind = Local, name = name, typ = "TNimTypeV2"):
       var typeInit: StructInitializer
       typeEntry.addStructInitializer(typeInit, kind = siNamedStruct):
         typeEntry.addField(typeInit, name = "destructor"):
@@ -1843,7 +1840,7 @@ proc genTypeInfoV2Impl(m: BModule; t, origType: PType, name: Rope; info: TLineIn
         else:
           typeEntry.addField(typeInit, name = "flags"):
             typeEntry.addIntValue(flags)
-  m.s[cfsVars].add typeEntry
+  m.s[cfsVars].add extract(typeEntry)
 
   if t.kind == tyObject and t.baseClass != nil and optEnableDeepCopy in m.config.globalOptions:
     discard genTypeInfoV1(m, t, info)
diff --git a/compiler/cgen.nim b/compiler/cgen.nim
index e330033f55f3..5666a2ff3581 100644
--- a/compiler/cgen.nim
+++ b/compiler/cgen.nim
@@ -16,7 +16,7 @@ import
   rodutils, renderer, cgendata, aliases,
   lowerings, lineinfos, pathutils, transf,
   injectdestructors, astmsgs, modulepaths, pushpoppragmas,
-  mangleutils
+  mangleutils, cbuilderbase
 
 from expanddefaults import caseObjDefaultBranch
 
@@ -138,6 +138,9 @@ proc cgFormatValue(result: var string; value: BiggestInt) =
 proc cgFormatValue(result: var string; value: Int128) =
   result.addInt128 value
 
+template addf(result: var Builder, args: varargs[untyped]) =
+  result.buf.addf(args)
+
 # TODO: please document
 macro ropecg(m: BModule, frmt: static[FormatStr], args: untyped): Rope =
   args.expectKind nnkBracket
@@ -237,7 +240,15 @@ proc addIndent(p: BProc; result: var Rope) =
     result[i] = '\t'
     inc i
 
-template appcg(m: BModule, c: var Rope, frmt: FormatStr,
+proc addIndent(p: BProc; result: var Builder) =
+  var i = result.buf.len
+  let newLen = i + p.blocks.len
+  result.buf.setLen newLen
+  while i < newLen:
+    result.buf[i] = '\t'
+    inc i
+
+template appcg(m: BModule, c: var (Rope | Builder), frmt: FormatStr,
            args: untyped) =
   c.add(ropecg(m, frmt, args))
 
@@ -275,7 +286,7 @@ proc safeLineNm(info: TLineInfo): int =
 proc genPostprocessDir(field1, field2, field3: string): string =
   result = postprocessDirStart & field1 & postprocessDirSep & field2 & postprocessDirSep & field3 & postprocessDirEnd
 
-proc genCLineDir(r: var Rope, fileIdx: FileIndex, line: int; conf: ConfigRef) =
+proc genCLineDir(r: var Builder, fileIdx: FileIndex, line: int; conf: ConfigRef) =
   assert line >= 0
   if optLineDir in conf.options and line > 0:
     if fileIdx == InvalidFileIdx:
@@ -283,7 +294,7 @@ proc genCLineDir(r: var Rope, fileIdx: FileIndex, line: int; conf: ConfigRef) =
     else:
       r.add(rope("\n#line " & $line & " FX_" & $fileIdx.int32 & "\n"))
 
-proc genCLineDir(r: var Rope, fileIdx: FileIndex, line: int; p: BProc; info: TLineInfo; lastFileIndex: FileIndex) =
+proc genCLineDir(r: var Builder, fileIdx: FileIndex, line: int; p: BProc; info: TLineInfo; lastFileIndex: FileIndex) =
   assert line >= 0
   if optLineDir in p.config.options and line > 0:
     if fileIdx == InvalidFileIdx:
@@ -291,7 +302,7 @@ proc genCLineDir(r: var Rope, fileIdx: FileIndex, line: int; p: BProc; info: TLi
     else:
       r.add(rope("\n#line " & $line & " FX_" & $fileIdx.int32 & "\n"))
 
-proc genCLineDir(r: var Rope, info: TLineInfo; conf: ConfigRef) =
+proc genCLineDir(r: var Builder, info: TLineInfo; conf: ConfigRef) =
   if optLineDir in conf.options:
     genCLineDir(r, info.fileIndex, info.safeLineNm, conf)
 
@@ -304,7 +315,7 @@ proc freshLineInfo(p: BProc; info: TLineInfo): bool =
   else:
     result = false
 
-proc genCLineDir(r: var Rope, p: BProc, info: TLineInfo; conf: ConfigRef) =
+proc genCLineDir(r: var Builder, p: BProc, info: TLineInfo; conf: ConfigRef) =
   if optLineDir in conf.options:
     let lastFileIndex = p.lastLineInfo.fileIndex
     if freshLineInfo(p, info):
@@ -328,7 +339,7 @@ proc genLineDir(p: BProc, t: PNode) =
 proc accessThreadLocalVar(p: BProc, s: PSym)
 proc emulatedThreadVars(conf: ConfigRef): bool {.inline.}
 proc genProc(m: BModule, prc: PSym)
-proc raiseInstr(p: BProc; result: var Rope)
+proc raiseInstr(p: BProc; result: var Builder)
 
 template compileToCpp(m: BModule): untyped =
   m.config.backend == backendCpp or sfCompileToCpp in m.module.flags
@@ -340,7 +351,6 @@ proc getTempName(m: BModule): Rope =
 proc isNoReturn(m: BModule; s: PSym): bool {.inline.} =
   sfNoReturn in s.flags and m.config.exc != excGoto
 
-include cbuilderbase
 include cbuilderexprs
 include cbuilderdecls
 include cbuilderstmts
@@ -613,28 +623,29 @@ proc getIntTemp(p: BProc): TLoc =
   linefmt(p, cpsLocals, "NI $1;$n", [result.snippet])
 
 proc localVarDecl(p: BProc; n: PNode): Rope =
-  result = ""
+  var res = newBuilder("")
   let s = n.sym
   if s.loc.k == locNone:
     fillLocalName(p, s)
     fillLoc(s.loc, locLocalVar, n, OnStack)
     if s.kind == skLet: incl(s.loc.flags, lfNoDeepCopy)
   if s.kind in {skLet, skVar, skField, skForVar} and s.alignment > 0:
-    result.addf("NIM_ALIGN($1) ", [rope(s.alignment)])
+    res.addf("NIM_ALIGN($1) ", [rope(s.alignment)])
 
-  genCLineDir(result, p, n.info, p.config)
+  genCLineDir(res, p, n.info, p.config)
 
-  result.add getTypeDesc(p.module, s.typ, dkVar)
+  res.add getTypeDesc(p.module, s.typ, dkVar)
   if sfCodegenDecl notin s.flags:
-    if sfRegister in s.flags: result.add(" register")
+    if sfRegister in s.flags: res.add(" register")
     #elif skipTypes(s.typ, abstractInst).kind in GcTypeKinds:
     #  decl.add(" GC_GUARD")
-    if sfVolatile in s.flags: result.add(" volatile")
-    if sfNoalias in s.flags: result.add(" NIM_NOALIAS")
-    result.add(" ")
-    result.add(s.loc.snippet)
+    if sfVolatile in s.flags: res.add(" volatile")
+    if sfNoalias in s.flags: res.add(" NIM_NOALIAS")
+    res.add(" ")
+    res.add(s.loc.snippet)
+    result = extract(res)
   else:
-    result = runtimeFormat(s.cgDeclFrmt, [result, s.loc.snippet])
+    result = runtimeFormat(s.cgDeclFrmt, [extract(res), s.loc.snippet])
 
 proc assignLocalVar(p: BProc, n: PNode) =
   #assert(s.loc.k == locNone) # not yet assigned
@@ -770,7 +781,7 @@ proc genStmts(p: BProc, t: PNode)
 proc expr(p: BProc, n: PNode, d: var TLoc)
 
 proc putLocIntoDest(p: BProc, d: var TLoc, s: TLoc)
-proc genLiteral(p: BProc, n: PNode; result: var Rope)
+proc genLiteral(p: BProc, n: PNode; result: var Builder)
 proc genOtherArg(p: BProc; ri: PNode; i: int; typ: PType; result: var Rope; argsCounter: var int)
 proc raiseExit(p: BProc)
 proc raiseExitCleanup(p: BProc, destroy: string)
@@ -807,7 +818,7 @@ $1define nimlf_(n, file) \
   FR_.line = n; FR_.filename = file;
 
 """
-  if p.module.s[cfsFrameDefines].len == 0:
+  if p.module.s[cfsFrameDefines].buf.len == 0:
     appcg(p.module, p.module.s[cfsFrameDefines], frameDefines, ["#"])
 
   cgsym(p.module, "nimFrame")
@@ -848,7 +859,7 @@ proc loadDynamicLib(m: BModule, lib: PLib) =
       var s: TStringSeq = @[]
       libCandidates(lib.path.strVal, s)
       rawMessage(m.config, hintDependency, lib.path.strVal)
-      var loadlib: Rope = ""
+      var loadlib = newBuilder("")
       for i in 0..high(s):
         inc(m.labels)
         if i > 0: loadlib.add("||")
@@ -859,7 +870,7 @@ proc loadDynamicLib(m: BModule, lib: PLib) =
         loadlib.addf "))$n", []
       appcg(m, m.s[cfsDynLibInit],
             "if (!($1)) #nimLoadLibraryError(",
-            [loadlib])
+            [extract(loadlib)])
       genStringLiteral(m, lib.path, m.s[cfsDynLibInit])
       m.s[cfsDynLibInit].addf ");$n", []
 
@@ -873,9 +884,9 @@ proc loadDynamicLib(m: BModule, lib: PLib) =
            [getTypeDesc(m, lib.path.typ, dkVar), rdLoc(dest)])
       expr(p, lib.path, dest)
 
-      m.s[cfsVars].add(p.s(cpsLocals))
-      m.s[cfsDynLibInit].add(p.s(cpsInit))
-      m.s[cfsDynLibInit].add(p.s(cpsStmts))
+      m.s[cfsVars].add(extract(p.s(cpsLocals)))
+      m.s[cfsDynLibInit].add(extract(p.s(cpsInit)))
+      m.s[cfsDynLibInit].add(extract(p.s(cpsStmts)))
       appcg(m, m.s[cfsDynLibInit],
            "if (!($1 = #nimLoadLibrary($2))) #nimLoadLibraryError($2);$n",
            [tmp, rdLoc(dest)])
@@ -995,12 +1006,12 @@ proc generateHeaders(m: BModule) =
 #undef unix
 """)
 
-proc openNamespaceNim(namespace: string; result: var Rope) =
+proc openNamespaceNim(namespace: string; result: var Builder) =
   result.add("namespace ")
   result.add(namespace)
   result.add(" {\L")
 
-proc closeNamespaceNim(result: var Rope) =
+proc closeNamespaceNim(result: var Builder) =
   result.add("}\L")
 
 proc closureSetup(p: BProc, prc: PSym) =
@@ -1185,9 +1196,10 @@ proc getProcTypeCast(m: BModule, prc: PSym): Rope =
   result = getTypeDesc(m, prc.loc.t)
   if prc.typ.callConv == ccClosure:
     var rettype: Snippet = ""
-    var params = newBuilder("")
+    var desc = newBuilder("")
     var check = initIntSet()
-    genProcParams(m, prc.typ, rettype, params, check)
+    genProcParams(m, prc.typ, rettype, desc, check)
+    let params = extract(desc)
     result = procPtrTypeUnnamed(rettype = rettype, params = params)
 
 proc genProcBody(p: BProc; procBody: PNode) =
@@ -1201,14 +1213,14 @@ proc genProcBody(p: BProc; procBody: PNode) =
 
 proc genProcAux*(m: BModule, prc: PSym) =
   var p = newProc(prc, m)
-  var header = newRopeAppender()
+  var header = newBuilder("")
   let isCppMember = m.config.backend == backendCpp and sfCppMember * prc.flags != {}
   var visibility: DeclVisibility = None
   if isCppMember:
     genMemberProcHeader(m, prc, header)
   else:
     genProcHeader(m, prc, header, visibility, asPtr = false, addAttributes = false)
-  var returnStmt: Rope = ""
+  var returnStmt: Snippet = ""
   assert(prc.ast != nil)
 
   var procBody = transformBody(m.g.graph, m.idgen, prc, {})
@@ -1241,9 +1253,10 @@ proc genProcAux*(m: BModule, prc: PSym) =
           discard "result init optimized out"
         else:
           initLocalVar(p, res, immediateAsgn=false)
-      returnStmt = "\t"
+      var returnBuilder = newBuilder("\t")
       let rres = rdLoc(res.loc)
-      returnStmt.addReturn(rres)
+      returnBuilder.addReturn(rres)
+      returnStmt = extract(returnBuilder)
     elif sfConstructor in prc.flags:
       resNode.sym.loc.flags.incl lfIndirect
       fillLoc(resNode.sym.loc, locParam, resNode, "this", OnHeap)
@@ -1278,27 +1291,27 @@ proc genProcAux*(m: BModule, prc: PSym) =
   generatedProc.genCLineDir prc.info, m.config
   generatedProc.addDeclWithVisibility(visibility):
     if sfPure in prc.flags:
-      generatedProc.add(header)
+      generatedProc.add(extract(header))
       generatedProc.finishProcHeaderWithBody():
-        generatedProc.add(p.s(cpsLocals))
-        generatedProc.add(p.s(cpsInit))
-        generatedProc.add(p.s(cpsStmts))
+        generatedProc.add(extract(p.s(cpsLocals)))
+        generatedProc.add(extract(p.s(cpsInit)))
+        generatedProc.add(extract(p.s(cpsStmts)))
     else:
       if m.hcrOn and isReloadable(m, prc):
         m.s[cfsProcHeaders].addDeclWithVisibility(visibility):
           # Add forward declaration for "_actual"-suffixed functions defined in the same module (or inline).
           # This fixes the use of methods and also the case when 2 functions within the same module
           # call each other using directly the "_actual" versions (an optimization) - see issue #11608
-          m.s[cfsProcHeaders].add(header)
+          m.s[cfsProcHeaders].add(extract(header))
           m.s[cfsProcHeaders].finishProcHeaderAsProto()
-      generatedProc.add(header)
+      generatedProc.add(extract(header))
       generatedProc.finishProcHeaderWithBody():
         if optStackTrace in prc.options:
-          generatedProc.add(p.s(cpsLocals))
+          generatedProc.add(extract(p.s(cpsLocals)))
           var procname = makeCString(prc.name.s)
           generatedProc.add(initFrame(p, procname, quotedFilename(p.config, prc.info)))
         else:
-          generatedProc.add(p.s(cpsLocals))
+          generatedProc.add(extract(p.s(cpsLocals)))
         if optProfiler in prc.options:
           # invoke at proc entry for recursion:
           p.s(cpsInit).add('\t')
@@ -1307,15 +1320,15 @@ proc genProcAux*(m: BModule, prc: PSym) =
           # this pair of {} is required for C++ (C++ is weird with its
           # control flow integrity checks):
           generatedProc.addScope():
-            generatedProc.add(p.s(cpsInit))
-            generatedProc.add(p.s(cpsStmts))
+            generatedProc.add(extract(p.s(cpsInit)))
+            generatedProc.add(extract(p.s(cpsStmts)))
           generatedProc.addLabel("BeforeRet_")
         else:
-          generatedProc.add(p.s(cpsInit))
-          generatedProc.add(p.s(cpsStmts))
+          generatedProc.add(extract(p.s(cpsInit)))
+          generatedProc.add(extract(p.s(cpsStmts)))
         if optStackTrace in prc.options: generatedProc.add(deinitFrame(p))
         generatedProc.add(returnStmt)
-  m.s[cfsProcs].add(generatedProc)
+  m.s[cfsProcs].add(extract(generatedProc))
   if isReloadable(m, prc):
     m.s[cfsDynLibInit].add('\t')
     m.s[cfsDynLibInit].addAssignmentWithValue(prc.loc.snippet):
@@ -1356,13 +1369,13 @@ proc genProcPrototype(m: BModule, sym: PSym) =
               '"' & name & '"')
   elif not containsOrIncl(m.declaredProtos, sym.id):
     let asPtr = isReloadable(m, sym)
-    var header = newRopeAppender()
+    var header = newBuilder("")
     var visibility: DeclVisibility = None
     genProcHeader(m, sym, header, visibility, asPtr = asPtr, addAttributes = true)
     if asPtr:
       m.s[cfsProcHeaders].addDeclWithVisibility(visibility):
         # genProcHeader would give variable declaration, add it directly
-        m.s[cfsProcHeaders].add(header)
+        m.s[cfsProcHeaders].add(extract(header))
     else:
       let extraVis =
         if sym.typ.callConv != ccInline and requiresExternC(m, sym):
@@ -1371,7 +1384,7 @@ proc genProcPrototype(m: BModule, sym: PSym) =
           None
       m.s[cfsProcHeaders].addDeclWithVisibility(extraVis):
         m.s[cfsProcHeaders].addDeclWithVisibility(visibility):
-          m.s[cfsProcHeaders].add(header)
+          m.s[cfsProcHeaders].add(extract(header))
           m.s[cfsProcHeaders].finishProcHeaderAsProto()
 
 # TODO: figure out how to rename this - it DOES generate a forward declaration
@@ -1498,7 +1511,7 @@ proc genVarPrototype(m: BModule, n: PNode) =
         "\t$1 = ($2*)hcrGetGlobal($3, \"$1\");$n", [sym.loc.snippet,
         getTypeDesc(m, sym.loc.t, dkVar), getModuleDllPath(m, sym)])
 
-proc addNimDefines(result: var Rope; conf: ConfigRef) {.inline.} =
+proc addNimDefines(result: var Builder; conf: ConfigRef) {.inline.} =
   result.addf("#define NIM_INTBITS $1\L", [
     platform.CPU[conf.target.targetCPU].intSize.rope])
   if conf.cppCustomNamespace.len > 0:
@@ -1522,9 +1535,10 @@ proc getCopyright(conf: ConfigRef; cfile: Cfile): Rope =
         rope(getCompileCFileCmd(conf, cfile))]
 
 proc getFileHeader(conf: ConfigRef; cfile: Cfile): Rope =
-  result = getCopyright(conf, cfile)
-  if conf.hcrOn: result.add("#define NIM_HOT_CODE_RELOADING\L")
-  addNimDefines(result, conf)
+  var res = newBuilder(getCopyright(conf, cfile))
+  if conf.hcrOn: res.add("#define NIM_HOT_CODE_RELOADING\L")
+  addNimDefines(res, conf)
+  result = extract(res)
 
 proc getSomeNameForModule(conf: ConfigRef, filename: AbsoluteFile): Rope =
   ## Returns a mangled module name.
@@ -1567,8 +1581,9 @@ proc genMainProc(m: BModule) =
       assert prc != nil
       let n = newStrNode(nkStrLit, prc.annex.path.strVal)
       n.info = prc.annex.path.info
-      var strLit = newRopeAppender()
-      genStringLiteral(m, n, strLit)
+      var strLitBuilder = newBuilder("")
+      genStringLiteral(m, n, strLitBuilder)
+      let strLit = extract(strLitBuilder)
       appcg(m, result, "\tif (!($1 = #nimLoadLibrary($2)))$N" &
                        "\t\t#nimLoadLibraryError($2);$N",
                        [handle, strLit])
@@ -1780,10 +1795,10 @@ proc registerInitProcs*(g: BModuleList; m: PSym; flags: set[ModuleBackendFlag])
 proc whichInitProcs*(m: BModule): set[ModuleBackendFlag] =
   # called from IC.
   result = {}
-  if m.hcrOn or m.preInitProc.s(cpsInit).len > 0 or m.preInitProc.s(cpsStmts).len > 0:
+  if m.hcrOn or m.preInitProc.s(cpsInit).buf.len > 0 or m.preInitProc.s(cpsStmts).buf.len > 0:
     result.incl HasModuleInitProc
   for i in cfsTypeInit1..cfsDynLibInit:
-    if m.s[i].len != 0:
+    if m.s[i].buf.len != 0:
       result.incl HasDatInitProc
       break
 
@@ -1836,7 +1851,7 @@ proc registerModuleToMain(g: BModuleList; m: BModule) =
       m.s[cfsInitProc].add(hcrModuleMeta)
     return
 
-  if m.s[cfsDatInitProc].len > 0:
+  if m.s[cfsDatInitProc].buf.len > 0:
     g.mainModProcs.addf("N_LIB_PRIVATE N_NIMCALL(void, $1)(void);$N", [datInit])
     g.mainDatInit.addf("\t$1();$N", [datInit])
 
@@ -1848,7 +1863,7 @@ proc registerModuleToMain(g: BModuleList; m: BModule) =
     if m.config.target.targetOS != osStandalone and m.config.selectedGC notin {gcNone, gcArc, gcAtomicArc, gcOrc}:
       g.mainDatInit.add(ropecg(m, "\t#initStackBottomWith((void *)&inner);$N", []))
 
-  if m.s[cfsInitProc].len > 0:
+  if m.s[cfsInitProc].buf.len > 0:
     g.mainModProcs.addf("N_LIB_PRIVATE N_NIMCALL(void, $1)(void);$N", [init])
     let initCall = "\t$1();$N" % [init]
     if sfMainModule in m.module.flags:
@@ -1865,22 +1880,22 @@ proc genDatInitCode(m: BModule) =
 
   var moduleDatInitRequired = m.hcrOn
 
-  var prc = "$1 N_NIMCALL(void, $2)(void) {$N" %
-    [rope(if m.hcrOn: "N_LIB_EXPORT" else: "N_LIB_PRIVATE"), getDatInitName(m)]
+  var prc = newBuilder("$1 N_NIMCALL(void, $2)(void) {$N" %
+    [rope(if m.hcrOn: "N_LIB_EXPORT" else: "N_LIB_PRIVATE"), getDatInitName(m)])
 
   # we don't want to break into such init code - could happen if a line
   # directive from a function written by the user spills after itself
   genCLineDir(prc, InvalidFileIdx, 999999, m.config)
 
   for i in cfsTypeInit1..cfsDynLibInit:
-    if m.s[i].len != 0:
+    if m.s[i].buf.len != 0:
       moduleDatInitRequired = true
-      prc.add(m.s[i])
+      prc.add(extract(m.s[i]))
 
   prc.addf("}$N$N", [])
 
   if moduleDatInitRequired:
-    m.s[cfsDatInitProc].add(prc)
+    m.s[cfsDatInitProc].add(extract(prc))
     #rememberFlag(m.g.graph, m.module, HasDatInitProc)
 
 # Very similar to the contents of symInDynamicLib - basically only the
@@ -1907,8 +1922,8 @@ proc genInitCode(m: BModule) =
   ## into other modules, only simple rope manipulations are allowed
   var moduleInitRequired = m.hcrOn
   let initname = getInitName(m)
-  var prc = "$1 N_NIMCALL(void, $2)(void) {$N" %
-    [rope(if m.hcrOn: "N_LIB_EXPORT" else: "N_LIB_PRIVATE"), initname]
+  var prc = newBuilder("$1 N_NIMCALL(void, $2)(void) {$N" %
+    [rope(if m.hcrOn: "N_LIB_EXPORT" else: "N_LIB_PRIVATE"), initname])
   # we don't want to break into such init code - could happen if a line
   # directive from a function written by the user spills after itself
   genCLineDir(prc, InvalidFileIdx, 999999, m.config)
@@ -1931,13 +1946,13 @@ proc genInitCode(m: BModule) =
       [getModuleDllPath(m, m.module)])
 
   template writeSection(thing: untyped, section: TCProcSection, addHcrGuards = false) =
-    if m.thing.s(section).len > 0:
+    if m.thing.s(section).buf.len > 0:
       moduleInitRequired = true
       if addHcrGuards: prc.add("\tif (nim_hcr_do_init_) {\n\n")
-      prc.add(m.thing.s(section))
+      prc.add(extract(m.thing.s(section)))
       if addHcrGuards: prc.add("\n\t} // nim_hcr_do_init_\n")
 
-  if m.preInitProc.s(cpsInit).len > 0 or m.preInitProc.s(cpsStmts).len > 0:
+  if m.preInitProc.s(cpsInit).buf.len > 0 or m.preInitProc.s(cpsStmts).buf.len > 0:
     # Give this small function its own scope
     prc.addf("{$N", [])
     # Keep a bogus frame in case the code needs one
@@ -1957,7 +1972,7 @@ proc genInitCode(m: BModule) =
   prc.addf("{$N", [])
   writeSection(initProc, cpsLocals)
 
-  if m.initProc.s(cpsInit).len > 0 or m.initProc.s(cpsStmts).len > 0:
+  if m.initProc.s(cpsInit).buf.len > 0 or m.initProc.s(cpsStmts).buf.len > 0:
     moduleInitRequired = true
     if optStackTrace in m.initProc.options and frameDeclared notin m.flags:
       # BUT: the generated init code might depend on a current frame, so
@@ -2011,14 +2026,14 @@ proc genInitCode(m: BModule) =
       prc.add(ex)
 
   if moduleInitRequired or sfMainModule in m.module.flags:
-    m.s[cfsInitProc].add(prc)
+    m.s[cfsInitProc].add(extract(prc))
     #rememberFlag(m.g.graph, m.module, HasModuleInitProc)
 
   genDatInitCode(m)
 
   if m.hcrOn:
     m.s[cfsInitProc].addf("N_LIB_EXPORT N_NIMCALL(void, HcrCreateTypeInfos)(void) {$N", [])
-    m.s[cfsInitProc].add(m.hcrCreateTypeInfosProc)
+    m.s[cfsInitProc].add(extract(m.hcrCreateTypeInfosProc))
     m.s[cfsInitProc].addf("}$N$N", [])
 
   registerModuleToMain(m.g, m)
@@ -2060,31 +2075,32 @@ proc postprocessCode(conf: ConfigRef, r: var Rope) =
 proc genModule(m: BModule, cfile: Cfile): Rope =
   var moduleIsEmpty = true
 
-  result = getFileHeader(m.config, cfile)
+  var res = newBuilder(getFileHeader(m.config, cfile))
 
   generateThreadLocalStorage(m)
   generateHeaders(m)
-  result.add(m.s[cfsHeaders])
+  res.add(extract(m.s[cfsHeaders]))
   if m.config.cppCustomNamespace.len > 0:
-    openNamespaceNim(m.config.cppCustomNamespace, result)
-  if m.s[cfsFrameDefines].len > 0:
-    result.add(m.s[cfsFrameDefines])
+    openNamespaceNim(m.config.cppCustomNamespace, res)
+  if m.s[cfsFrameDefines].buf.len > 0:
+    res.add(extract(m.s[cfsFrameDefines]))
 
   for i in cfsForwardTypes..cfsProcs:
-    if m.s[i].len > 0:
+    if m.s[i].buf.len > 0:
       moduleIsEmpty = false
-      result.add(m.s[i])
+      res.add(extract(m.s[i]))
 
-  if m.s[cfsInitProc].len > 0:
+  if m.s[cfsInitProc].buf.len > 0:
     moduleIsEmpty = false
-    result.add(m.s[cfsInitProc])
-  if m.s[cfsDatInitProc].len > 0 or m.hcrOn:
+    res.add(extract(m.s[cfsInitProc]))
+  if m.s[cfsDatInitProc].buf.len > 0 or m.hcrOn:
     moduleIsEmpty = false
-    result.add(m.s[cfsDatInitProc])
+    res.add(extract(m.s[cfsDatInitProc]))
 
   if m.config.cppCustomNamespace.len > 0:
-    closeNamespaceNim(result)
+    closeNamespaceNim(res)
 
+  result = extract(res)
   if optLineDir in m.config.options:
     var srcFileDefs = ""
     for fi in 0..m.config.m.fileInfos.high:
@@ -2115,11 +2131,12 @@ proc rawNewModule(g: BModuleList; module: PSym, filename: AbsoluteFile): BModule
   result.typeInfoMarker = initTable[SigHash, Rope]()
   result.sigConflicts = initCountTable[SigHash]()
   result.initProc = newProc(nil, result)
-  for i in low(result.s)..high(result.s): result.s[i] = newRopeAppender()
+  for i in low(result.s)..high(result.s): result.s[i] = newBuilder("")
   result.initProc.options = initProcOptions(result)
   result.preInitProc = newProc(nil, result)
   result.preInitProc.flags.incl nimErrorFlagDisabled
   result.preInitProc.labels = 100_000 # little hack so that unique temporaries are generated
+  result.hcrCreateTypeInfosProc = newBuilder("")
   result.dataCache = initNodeTable()
   result.typeStack = @[]
   result.typeNodesName = getTempName(result)
@@ -2158,7 +2175,7 @@ proc setupCgen*(graph: ModuleGraph; module: PSym; idgen: IdGenerator): PPassCont
     incl g.generatedHeader.flags, isHeaderFile
 
 proc writeHeader(m: BModule) =
-  var result = headerTop()
+  var result = newBuilder(headerTop())
   var guard = "__$1__" % [m.filename.splitFile.name.rope]
   result.addf("#ifndef $1$n#define $1$n", [guard])
   addNimDefines(result, m.config)
@@ -2166,17 +2183,17 @@ proc writeHeader(m: BModule) =
 
   generateThreadLocalStorage(m)
   for i in cfsHeaders..cfsProcs:
-    result.add(m.s[i])
+    result.add(extract(m.s[i]))
     if m.config.cppCustomNamespace.len > 0 and i == cfsHeaders:
       openNamespaceNim(m.config.cppCustomNamespace, result)
-  result.add(m.s[cfsInitProc])
+  result.add(extract(m.s[cfsInitProc]))
 
   if optGenDynLib in m.config.globalOptions:
     result.add("N_LIB_IMPORT ")
   result.addf("N_CDECL(void, $1NimMain)(void);$n", [rope m.config.nimMainPrefix])
   if m.config.cppCustomNamespace.len > 0: closeNamespaceNim(result)
   result.addf("#endif /* $1 */$n", [guard])
-  if not writeRope(result, m.filename):
+  if not writeRope(extract(result), m.filename):
     rawMessage(m.config, errCannotOpenFile, m.filename.string)
 
 proc getCFile(m: BModule): AbsoluteFile =
diff --git a/compiler/cgendata.nim b/compiler/cgendata.nim
index 7bc273df300d..3dc042174fd5 100644
--- a/compiler/cgendata.nim
+++ b/compiler/cgendata.nim
@@ -11,7 +11,7 @@
 
 import
   ast, ropes, options,
-  lineinfos, pathutils, modulegraphs
+  lineinfos, pathutils, modulegraphs, cbuilderbase
 
 import std/[intsets, tables, sets]
 
@@ -43,12 +43,12 @@ type
     ctUInt, ctUInt8, ctUInt16, ctUInt32, ctUInt64,
     ctArray, ctPtrToArray, ctStruct, ctPtr, ctNimStr, ctNimSeq, ctProc,
     ctCString
-  TCFileSections* = array[TCFileSection, Rope] # represents a generated C file
+  TCFileSections* = array[TCFileSection, Builder] # represents a generated C file
   TCProcSection* = enum       # the sections a generated C proc consists of
     cpsLocals,                # section of local variables for C proc
     cpsInit,                  # section for init of variables for C proc
     cpsStmts                  # section of local statements for C proc
-  TCProcSections* = array[TCProcSection, Rope] # represents a generated C proc
+  TCProcSections* = array[TCProcSection, Builder] # represents a generated C proc
   BModule* = ref TCGen
   BProc* = ref TCProc
   TBlock* = object
@@ -161,7 +161,7 @@ type
     typeInfoMarkerV2*: TypeCache
     initProc*: BProc          # code for init procedure
     preInitProc*: BProc       # code executed before the init proc
-    hcrCreateTypeInfosProc*: Rope # type info globals are in here when HCR=on
+    hcrCreateTypeInfosProc*: Builder # type info globals are in here when HCR=on
     inHcrInitGuard*: bool     # We are currently within a HCR reloading guard.
     typeStack*: TTypeSeq      # used for type generation
     dataCache*: TNodeTable
@@ -181,18 +181,18 @@ proc includeHeader*(this: BModule; header: string) =
   if not this.headerFiles.contains header:
     this.headerFiles.add header
 
-proc s*(p: BProc, s: TCProcSection): var Rope {.inline.} =
+proc s*(p: BProc, s: TCProcSection): var Builder {.inline.} =
   # section in the current block
   result = p.blocks[^1].sections[s]
 
-proc procSec*(p: BProc, s: TCProcSection): var Rope {.inline.} =
+proc procSec*(p: BProc, s: TCProcSection): var Builder {.inline.} =
   # top level proc sections
   result = p.blocks[0].sections[s]
 
 proc initBlock*(): TBlock =
   result = TBlock()
   for i in low(result.sections)..high(result.sections):
-    result.sections[i] = newRopeAppender()
+    result.sections[i] = newBuilder("")
 
 proc newProc*(prc: PSym, module: BModule): BProc =
   result = BProc(
diff --git a/lib/pure/httpclient.nim b/lib/pure/httpclient.nim
index 08ea99627c1c..654bed27bc91 100644
--- a/lib/pure/httpclient.nim
+++ b/lib/pure/httpclient.nim
@@ -62,6 +62,7 @@
 ## validated to the server.
 ##
 ##   ```Nim
+##   import std/[httpclient]
 ##   var client = newHttpClient()
 ##   var data = newMultipartData()
 ##   data["output"] = "soap12"
@@ -79,6 +80,7 @@
 ## it, you can pass your own via the `mimeDb` parameter to avoid this.
 ##
 ##   ```Nim
+##   import std/[httpclient, mimetypes]
 ##   let mimes = newMimetypes()
 ##   var client = newHttpClient()
 ##   var data = newMultipartData()
@@ -160,7 +162,7 @@
 ## Example of setting SSL verification parameters in a new client:
 ##
 ##   ```Nim
-##   import httpclient
+##   import std/[net, httpclient]
 ##   var client = newHttpClient(sslContext=newContext(verifyMode=CVerifyPeer))
 ##   ```
 ##
diff --git a/lib/pure/parsesql.nim b/lib/pure/parsesql.nim
index a7c938d0181a..4ea01c89d8de 100644
--- a/lib/pure/parsesql.nim
+++ b/lib/pure/parsesql.nim
@@ -507,12 +507,14 @@ type
     nkAsgn,
     nkFrom,
     nkFromItemPair,
+    nkJoin,
+    nkNaturalJoin,
+    nkUsing,
     nkGroup,
     nkLimit,
     nkOffset,
     nkHaving,
     nkOrder,
-    nkJoin,
     nkDesc,
     nkUnion,
     nkIntersect,
@@ -936,18 +938,75 @@ proc parseWhere(p: var SqlParser): SqlNode =
   result = newNode(nkWhere)
   result.add(parseExpr(p))
 
+proc parseJoinType(p: var SqlParser): SqlNode =
+  ## parse [ INNER ] JOIN | ( LEFT | RIGHT | FULL ) [ OUTER ] JOIN
+  if isKeyw(p, "inner"):
+    getTok(p)
+    eat(p, "join")
+    return newNode(nkIdent, "inner")
+  elif isKeyw(p, "join"):
+    getTok(p)
+    return newNode(nkIdent, "")
+  elif isKeyw(p, "left") or isKeyw(p, "full") or isKeyw(p, "right"):
+    var joinType = newNode(nkIdent, p.tok.literal.toLowerAscii())
+    getTok(p)
+    optKeyw(p, "outer")
+    eat(p, "join")
+    return joinType
+  else:
+    sqlError(p, "join type expected")
+
 proc parseFromItem(p: var SqlParser): SqlNode =
   result = newNode(nkFromItemPair)
+  var expectAs = true
   if p.tok.kind == tkParLe:
     getTok(p)
-    var select = parseSelect(p)
-    result.add(select)
+    if isKeyw(p, "select"):
+      result.add(parseSelect(p))
+    else:
+      result = parseFromItem(p)
+      expectAs = false
     eat(p, tkParRi)
   else:
     result.add(parseExpr(p))
-  if isKeyw(p, "as"):
+  if expectAs and isKeyw(p, "as"):
     getTok(p)
     result.add(parseExpr(p))
+  while true:
+    if isKeyw(p, "cross"):
+      var join = newNode(nkJoin)
+      join.add(newNode(nkIdent, "cross"))
+      join.add(result)
+      getTok(p)
+      eat(p, "join")
+      join.add(parseFromItem(p))
+      result = join
+    elif isKeyw(p, "natural"):
+      var join = newNode(nkNaturalJoin)
+      getTok(p)
+      join.add(parseJoinType(p))
+      join.add(result)
+      join.add(parseFromItem(p))
+      result = join
+    elif isKeyw(p, "inner") or isKeyw(p, "join") or isKeyw(p, "left") or
+        iskeyw(p, "full") or isKeyw(p, "right"):
+      var join = newNode(nkJoin)
+      join.add(parseJoinType(p))
+      join.add(result)
+      join.add(parseFromItem(p))
+      if isKeyw(p, "on"):
+        getTok(p)
+        join.add(parseExpr(p))
+      elif isKeyw(p, "using"):
+        getTok(p)
+        var n = newNode(nkUsing)
+        parseParIdentList(p, n)
+        join.add n
+      else:
+        sqlError(p, "ON or USING expected")
+      result = join
+    else:
+      break
 
 proc parseIndexDef(p: var SqlParser): SqlNode =
   result = parseIfNotExists(p, nkCreateIndex)
@@ -1109,19 +1168,6 @@ proc parseSelect(p: var SqlParser): SqlNode =
   elif isKeyw(p, "except"):
     result.add(newNode(nkExcept))
     getTok(p)
-  if isKeyw(p, "join") or isKeyw(p, "inner") or isKeyw(p, "outer") or isKeyw(p, "cross"):
-    var join = newNode(nkJoin)
-    result.add(join)
-    if isKeyw(p, "join"):
-      join.add(newNode(nkIdent, ""))
-      getTok(p)
-    else:
-      join.add(newNode(nkIdent, p.tok.literal.toLowerAscii()))
-      getTok(p)
-      eat(p, "join")
-    join.add(parseFromItem(p))
-    eat(p, "on")
-    join.add(parseExpr(p))
   if isKeyw(p, "limit"):
     getTok(p)
     var l = newNode(nkLimit)
@@ -1388,6 +1434,30 @@ proc ra(n: SqlNode, s: var SqlWriter) =
   of nkFrom:
     s.addKeyw("from")
     s.addMulti(n)
+  of nkJoin, nkNaturalJoin:
+    var joinType = n.sons[0].strVal
+    if joinType == "":
+      joinType = "join"
+    else:
+      joinType &= " " & "join"
+    if n.kind == nkNaturalJoin:
+      joinType = "natural " & joinType
+    ra(n.sons[1], s)
+    s.addKeyw(joinType)
+    # If the right part of the join is not leaf, parenthesize it
+    if n.sons[2].kind != nkFromItemPair:
+      s.add('(')
+      ra(n.sons[2], s)
+      s.add(')')
+    else:
+      ra(n.sons[2], s)
+    if n.sons.len > 3:
+      if n.sons[3].kind != nkUsing:
+        s.addKeyw("on")
+      ra(n.sons[3], s)
+  of nkUsing:
+    s.addKeyw("using")
+    rs(n, s)
   of nkGroup:
     s.addKeyw("group by")
     s.addMulti(n)
@@ -1403,16 +1473,6 @@ proc ra(n: SqlNode, s: var SqlWriter) =
   of nkOrder:
     s.addKeyw("order by")
     s.addMulti(n)
-  of nkJoin:
-    var joinType = n.sons[0].strVal
-    if joinType == "":
-      joinType = "join"
-    else:
-      joinType &= " " & "join"
-    s.addKeyw(joinType)
-    ra(n.sons[1], s)
-    s.addKeyw("on")
-    ra(n.sons[2], s)
   of nkDesc:
     ra(n.sons[0], s)
     s.addKeyw("desc")
diff --git a/tests/stdlib/tparsesql.nim b/tests/stdlib/tparsesql.nim
index cd582551df03..269ff7f8b1f6 100644
--- a/tests/stdlib/tparsesql.nim
+++ b/tests/stdlib/tparsesql.nim
@@ -159,17 +159,76 @@ INNER JOIN b
 ON a.id == b.id
 """) == "select id from a inner join b on a.id == b.id;"
 
-doAssert $parseSql("""
+# For OUTER joins, LEFT | RIGHT | FULL specifier is not optional
+doAssertRaises(SqlParseError): discard parseSql("""
 SELECT id FROM a
 OUTER JOIN b
-ON a.id == b.id
-""") == "select id from a outer join b on a.id == b.id;"
+ON a.id = b.id
+""")
 
-doAssert $parseSql("""
+# For NATURAL JOIN and CROSS JOIN, ON and USING clauses are forbidden
+doAssertRaises(SqlParseError): discard parseSql("""
 SELECT id FROM a
 CROSS JOIN b
-ON a.id == b.id
-""") == "select id from a cross join b on a.id == b.id;"
+ON a.id = b.id
+""")
+
+# JOIN should parse as part of FROM, not after WHERE
+doAssertRaises(SqlParseError): discard parseSql("""
+SELECT id FROM a
+WHERE a.id IS NOT NULL
+INNER JOIN b
+ON a.id = b.id
+""")
+
+# JOIN should parse as part of FROM, other fromItems may follow
+doAssert $parseSql("""
+SELECT id
+FROM
+    a JOIN b ON a.id = b.id,
+    c
+""") == "select id from a join b on a.id = b.id, c;"
+
+# LEFT JOIN should parse
+doAssert $parseSql("""
+SELECT id FROM a
+LEFT JOIN b
+ON a.id = b.id
+""") == "select id from a left join b on a.id = b.id;"
+
+# NATURAL JOIN should parse
+doAssert $parseSql("""
+SELECT id FROM a
+NATURAL JOIN b
+""") == "select id from a natural join b;"
+
+# USING should parse
+doAssert $parseSql("""
+SELECT id FROM a
+JOIN b
+USING (id)
+""") == "select id from a join b using (id );"
+
+# Multiple JOINs should parse
+doAssert $parseSql("""
+SELECT id FROM a
+JOIN b
+ON a.id = b.id
+LEFT JOIN c
+USING (id)
+""") == "select id from a join b on a.id = b.id left join c using (id );"
+
+# Parenthesized JOIN expressions should parse
+doAssert $parseSql("""
+SELECT id
+FROM a JOIN (b JOIN c USING (id)) ON a.id = b.id
+""") == "select id from a join(b join c using (id )) on a.id = b.id;"
+
+# Left-side parenthesized JOIN expressions should parse
+doAssert $parseSql("""
+SELECT id
+FROM (b JOIN c USING (id)) JOIN a ON a.id = b.id
+""") == "select id from b join c using (id ) join a on a.id = b.id;"
 
 doAssert $parseSql("""
 CREATE TYPE happiness AS ENUM ('happy', 'very happy', 'ecstatic');
diff --git a/tests/untestable/thttpclient_ssl_disabled.nim b/tests/untestable/thttpclient_ssl_disabled.nim
index b95dad2c64d5..e3d214763ed7 100644
--- a/tests/untestable/thttpclient_ssl_disabled.nim
+++ b/tests/untestable/thttpclient_ssl_disabled.nim
@@ -9,7 +9,8 @@
 ## nim r --putenv:NIM_TESTAMENT_REMOTE_NETWORKING:1 -d:nimDisableCertificateValidation -d:ssl -p:. tests/untestable/thttpclient_ssl_disabled.nim
 
 from stdtest/testutils import enableRemoteNetworking
-when enableRemoteNetworking and (defined(nimTestsEnableFlaky) or not defined(openbsd)):
+# badssl tests disabled indefinitely
+when false and enableRemoteNetworking and (defined(nimTestsEnableFlaky) or not defined(openbsd)):
   import httpclient, net, unittest
 
   const expired = "https://expired.badssl.com/"
diff --git a/tests/untestable/thttpclient_ssl_env_var.nim b/tests/untestable/thttpclient_ssl_env_var.nim
index 3f25a6ff4c08..5c99dc74e638 100644
--- a/tests/untestable/thttpclient_ssl_env_var.nim
+++ b/tests/untestable/thttpclient_ssl_env_var.nim
@@ -19,7 +19,6 @@ from net import newSocket, newContext, wrapSocket, connect, close, Port,
 from strutils import contains
 
 const
-  expired = "https://expired.badssl.com/"
   good = "https://google.com/"
 
 
@@ -56,12 +55,13 @@ suite "SSL certificate check":
       var ctx = newContext(verifyMode=CVerifyPeerUseEnvVars)
       ctx.wrapSocket(sock)
       checkpoint("Socket created")
-      try:
-        sock.connect("expired.badssl.com", 443.Port)
-        fail()
-      except:
-        sock.close
-        check getCurrentExceptionMsg().contains("certificate verify failed")
+      when false: # badssl tests disabled indefinitely
+        try:
+          sock.connect("expired.badssl.com", 443.Port)
+          fail()
+        except:
+          sock.close
+          check getCurrentExceptionMsg().contains("certificate verify failed")
 
     elif existsEnv("SSL_CERT_DIR"):
       var sock = newSocket()
diff --git a/tests/untestable/thttpclient_ssl_remotenetwork.nim b/tests/untestable/thttpclient_ssl_remotenetwork.nim
index 3cb759516293..5603154897b0 100644
--- a/tests/untestable/thttpclient_ssl_remotenetwork.nim
+++ b/tests/untestable/thttpclient_ssl_remotenetwork.nim
@@ -33,7 +33,8 @@ when enableRemoteNetworking and (defined(nimTestsEnableFlaky) or not defined(win
     CertTest = tuple[url:string, category:Category, desc: string]
 
   # badssl certs sometimes expire, set to false when that happens
-  when true:
+  # badssl now disabled indefinitely
+  when false:
     const certificate_tests: array[0..54, CertTest] = [
       ("https://wrong.host.badssl.com/", bad, "wrong.host"),
       ("https://captive-portal.badssl.com/", bad, "captive-portal"),
@@ -197,7 +198,7 @@ when enableRemoteNetworking and (defined(nimTestsEnableFlaky) or not defined(win
 
   type NetSocketTest = tuple[hostname: string, port: Port, category:Category, desc: string]
   # badssl certs sometimes expire, set to false when that happens
-  when true:
+  when false:
     const net_tests:array[0..3, NetSocketTest] = [
       ("imap.gmail.com", 993.Port, good, "IMAP"),
       ("wrong.host.badssl.com", 443.Port, bad, "wrong.host"),