Add ChplConfig.compiledForSingleLocale() query (#22730)

Adds the `compiledForSingleLocale()` query to the `ChplConfig` module,
which return true if the program is being compiled for a single locale.

This result is controlled by the `--[no-]local` flag, and if that is not
present then by `CHPL_COMM`. The output of the query is identical to the
compiler-provided `_local` variable, and many uses of `_local` in
modules are replaced by the query in this PR.

Resolves Cray/chapel-private#5019.

[reviewed by @jeremiah-corrado , thanks!]

Testing:
- [x] local paratest
- [x] gasnet paratest
- [x] tests pass (and skip as appropriate) for all combinations of
`CHPL_COMM` and `--[no-]local`

modules/dists/PrivateDist.chpl

@@ -18,6 +18,8 @@
  * limitations under the License.
  */
 
+use ChplConfig only compiledForSingleLocale;
+
 //
 // Private Distribution, Domain, and Array
 //  Defines PrivateSpace, an instance of PrivateDom
@@ -169,7 +171,6 @@ private proc checkCanMakeDefaultValue(type eltType) param {
 }
 
 class PrivateArr: BaseRectangularArr {
-
   var dom: unmanaged PrivateDom(rank, idxType, strides);
 
   // may be initialized separately
@@ -241,7 +242,7 @@ override proc PrivateArr.dsiDestroyArr(deinitElts:bool) {
     param needsDestroy = __primitive("needs auto destroy", eltType);
 
     if needsDestroy {
-      if _local {
+      if compiledForSingleLocale() {
         chpl__autoDestroy(data);
       } else {
         const pid = this.pid;
@@ -267,7 +268,7 @@ proc PrivateArr.dsiPrivatize(privatizeData) {
 }
 
 proc PrivateArr.dsiAccess(i: idxType) ref {
-  if _local then
+  if compiledForSingleLocale() then
     return data;
   else if i == here.id then
     return data;

modules/internal/ByteBufferHelpers.chpl

@@ -22,6 +22,7 @@ module ByteBufferHelpers {
   private use ChapelStandard;
   private use CTypes;
   private use OS.POSIX;
+  private use ChplConfig only compiledForSingleLocale;
 
   @chpldoc.nodoc
   type byteType = uint(8);
@@ -106,7 +107,7 @@ module ByteBufferHelpers {
   }
 
   inline proc bufferCopy(buf: bufferType, off: int, len: int, loc: locIdType) {
-    if !_local && loc != chpl_nodeID {
+    if !compiledForSingleLocale() && loc != chpl_nodeID {
       var newBuf = bufferCopyRemote(loc, buf+off, len);
       return (newBuf, len);
     }
@@ -118,7 +119,7 @@ module ByteBufferHelpers {
   //dst must be local
   inline proc bufferMemcpy(dst: bufferType, src_loc: int(64), src: bufferType,
                            len: int, dst_off: int=0, src_off: int=0) {
-    if !_local && src_loc != chpl_nodeID {
+    if !compiledForSingleLocale() && src_loc != chpl_nodeID {
       chpl_string_comm_get(dst+dst_off, src_loc, src+src_off, len);
     }
     else {
@@ -137,7 +138,7 @@ module ByteBufferHelpers {
   }
 
   inline proc bufferGetByte(buf: bufferType, off: int, loc: locIdType) {
-    if !_local && loc != chpl_nodeID {
+    if !compiledForSingleLocale() && loc != chpl_nodeID {
       const newBuf = bufferCopyRemote(src_loc_id=loc, src_addr=buf+off, len=1);
       const ret = newBuf[0];
       bufferFree(newBuf);

modules/internal/Bytes.chpl

@@ -28,6 +28,7 @@ module Bytes {
   private use ByteBufferHelpers;
   private use BytesStringCommon;
   private use CTypes;
+  private use ChplConfig only compiledForSingleLocale;
 
   public use BytesCasts;
   public use BytesStringCommon only decodePolicy;  // expose decodePolicy
@@ -505,7 +506,7 @@ module Bytes {
                current locale, otherwise a deep copy is performed.
   */
   inline proc bytes.localize() : bytes {
-    if _local || this.locale_id == chpl_nodeID {
+    if compiledForSingleLocale() || this.locale_id == chpl_nodeID {
       return bytes.createBorrowingBuffer(this);
     } else {
       const x:bytes = this; // assignment makes it local

modules/internal/BytesStringCommon.chpl

@@ -23,6 +23,7 @@ module BytesStringCommon {
   private use CTypes;
   private use ByteBufferHelpers;
   private use String.NVStringFactory;
+  private use ChplConfig only compiledForSingleLocale;
 
   extern const CHPL_SHORT_STRING_SIZE : c_int;
 
@@ -88,7 +89,7 @@ module BytesStringCommon {
   // issue (#448 chapel-private)
   inline proc getCStr(const ref x: ?t): c_string {
     assertArgType(t, "getCStr");
-    if _local == false && x.locale_id != chpl_nodeID then
+    if !compiledForSingleLocale() && x.locale_id != chpl_nodeID then
       halt("Cannot call .c_str() on a remote " + t:string);
 
     var buff: bufferType = x.buff;
@@ -323,7 +324,7 @@ module BytesStringCommon {
 
     if otherLen > 0 {
       x.buffLen = otherLen;
-      if !_local && otherRemote {
+      if !compiledForSingleLocale() && otherRemote {
         // if s is remote, copy and own the buffer
         x.buff = bufferCopyRemote(other.locale_id, other.buff, otherLen);
         x.buffSize = otherLen+1;
@@ -1137,7 +1138,7 @@ module BytesStringCommon {
     assertArgType(t, "doAssign");
 
     inline proc helpMe(ref lhs: t, rhs: t) {
-      if _local || rhs.locale_id == chpl_nodeID {
+      if compiledForSingleLocale() || rhs.locale_id == chpl_nodeID {
         if t == string {
           reinitWithNewBuffer(lhs, rhs.buff, rhs.buffLen, rhs.buffSize,
                               rhs.numCodepoints);
@@ -1160,7 +1161,7 @@ module BytesStringCommon {
       }
     }
 
-    if _local || lhs.locale_id == chpl_nodeID then {
+    if compiledForSingleLocale() || lhs.locale_id == chpl_nodeID then {
       helpMe(lhs, rhs);
     }
     else {

modules/internal/ChapelArray.chpl

@@ -33,6 +33,7 @@ module ChapelArray {
   use ChapelDebugPrint;
   use CTypes;
   use ChapelPrivatization;
+  use ChplConfig only compiledForSingleLocale;
   public use ChapelDomain;
 
   // Explicitly use a processor atomic, as most calls to this function are
@@ -80,9 +81,9 @@ module ChapelArray {
   config param logAllArrEltAccess = false;
 
   proc _isPrivatized(value) param do
-    return !_local && ((_privatization && value!.dsiSupportsPrivatization()) ||
-                       value!.dsiRequiresPrivatization());
-    // Note - _local=true means --local / single locale
+    return !compiledForSingleLocale() &&
+           ((_privatization && value!.dsiSupportsPrivatization()) ||
+            value!.dsiRequiresPrivatization());
     // _privatization is controlled by --[no-]privatization
     // privatization required, not optional, for PrivateDist
 

modules/internal/String.chpl

@@ -45,6 +45,7 @@ module String {
   use CTypes;
   use ByteBufferHelpers;
   use BytesStringCommon;
+  use ChplConfig only compiledForSingleLocale;
   import OS.{errorCode};
 
   use CString;
@@ -922,7 +923,7 @@ module String {
     // assumes that 'this' is already localized
     proc _cpIndexLenHelpNoAdjustment(ref start: int) {
       if boundsChecking {
-        if !_local && this.locale_id != chpl_nodeID {
+        if !compiledForSingleLocale() && this.locale_id != chpl_nodeID {
           halt("internal error -- method requires localized string");
         }
       }
@@ -1009,7 +1010,7 @@ module String {
                            const splitCount: int, const noSplits: bool,
                            const limitSplits: bool, const iEnd: byteIndex) {
       if boundsChecking {
-        if !_local && this.locale_id != chpl_nodeID {
+        if !compiledForSingleLocale() && this.locale_id != chpl_nodeID {
           halt("internal error -- method requires localized string");
         }
       }
@@ -1272,7 +1273,7 @@ module String {
                current locale, otherwise a deep copy is performed.
   */
   inline proc string.localize() : string {
-    if _local || this.locale_id == chpl_nodeID {
+    if compiledForSingleLocale() || this.locale_id == chpl_nodeID {
       return string.createBorrowingBuffer(this);
     } else {
       const x:string = this; // assignment makes it local

modules/packages/AtomicObjects.chpl

@@ -326,7 +326,7 @@ prototype module AtomicObjects {
     // faster compression method so we need to decompress it in the same way...
     var locId = descr >> compressedLocIdOffset;
     var addr = descr & compressedAddrMask;
-    if _local || locId == here.id then return castToObj(objType, addr);
+    if compiledForSingleLocale() || locId == here.id then return castToObj(objType, addr);
 
     // We've created the wide pointer, but unfortunately Chapel does not support
     // the ability to cast it to the actual object, so we have to do some
@@ -464,7 +464,7 @@ prototype module AtomicObjects {
     param hasGlobalSupport : bool;
     var atomicVar : if hasABASupport then _ddata(_ABAInternal(objType?)) else atomic uint(64);
 
-    proc init(type objType, param hasABASupport = false, param hasGlobalSupport = !_local) {
+    proc init(type objType, param hasABASupport = false, param hasGlobalSupport = !compiledForSingleLocale()) {
       if !isUnmanagedClass(objType) {
         compilerError ("LocalAtomicObject must take a 'unmanaged' type, not ", objType : string);
       }
@@ -481,7 +481,7 @@ prototype module AtomicObjects {
       }
     }
 
-    proc init(type objType, defaultValue : objType, param hasABASupport = false, param hasGlobalSupport = !_local) {
+    proc init(type objType, defaultValue : objType, param hasABASupport = false, param hasGlobalSupport = !compiledForSingleLocale()) {
       init(objType, hasABASupport, hasGlobalSupport);
       var ptr : uint(64);
       if hasGlobalSupport {
@@ -522,9 +522,9 @@ prototype module AtomicObjects {
         return compress(obj);
       } else {
         // Check if an object is non-local when 'hasGlobalSupport' is false
-        // Note: Both `_local` and `boundsChecking` are compile-time constants
-        // and will compile this away.
-        if !_local && boundsChecking {
+        // Note: Both `compiledForSingleLocale()` and `boundsChecking` are
+        // compile-time constants and will compile this away.
+        if !compiledForSingleLocale() && boundsChecking {
           localityCheck(obj);
         }
         return getAddr(obj);