Merge pull request #802 from murzinv/sve-basics

[all] Introduce basic support for SVE

This PR introduces basic support for SVE instructions in `litmus7`, `diy7` and `herd7`.

Scalable Vector Extension (SVE) is Vector Length Agnostic (VLA):
- Vector Length (VL) is a hardware implementation choice from 128 up to 2048 bits.
- New programming model allows software to scale dynamically to available vector length.
- No need to define a new ISA, rewrite or recompile for new vector lengths.

Scalable vector registers:
- Z0-Z31 extending NEON’s 128-bit V0-V31
- Packed DP, SP & HP floating-point elements
- Packed 64, 32, 16 & 8-bit integer elements
    
 Scalable predicate registers:
   
 - P0-P7 governing predicates for load/store/arithmetic
 - P8-P15 additional predicates for loop management
 - FFR first fault register for software speculation
 
 I personally find tutorial at [1] really great introduction to the SVE programming model.
 
 Implementation choices and known limitations:
     - SVE memory model is not addressed
     - `herd7` implements 128 bits vector length (on top of existing Neon infrastructure)
 
[1] https://www.stonybrook.edu/commcms/ookami/support/_docs/ARM_SVE_tutorial.pdf

Makefile

@@ -140,6 +140,18 @@ test.neon::
 		$(REGRESSION_TEST_MODE)
 	@ echo "herd7 AArch64 NEON instructions tests: OK"
 
+test:: test.sve
+test.sve::
+	@ echo
+	$(HERD_REGRESSION_TEST) \
+		-j $(J) \
+		-herd-path $(HERD) \
+		-libdir-path ./herd/libdir \
+		-litmus-dir ./herd/tests/instructions/AArch64.sve \
+		-variant sve \
+		$(REGRESSION_TEST_MODE)
+	@ echo "herd7 AArch64 SVE instructions tests: OK"
+
 test:: test.mte
 test.mte::
 	@ echo

gen/AArch64Arch_gen.ml

@@ -35,6 +35,7 @@ let do_morello = C.variant Variant_gen.Morello
 let do_fullkvm = C.variant Variant_gen.FullKVM
 let do_kvm = do_fullkvm || C.variant Variant_gen.KVM
 let do_neon = C.variant Variant_gen.Neon
+let do_sve = C.variant Variant_gen.SVE
 let do_mixed = Variant_gen.is_mixed  C.variant
 let do_cu = C.variant Variant_gen.ConstrainedUnpredictable
 
@@ -60,7 +61,7 @@ module Mixed =
 let bellatom = false
 module SIMD = struct
 
-  type atom = NeP|NeAcqPc|NeRel|Ne1|Ne2|Ne3|Ne4|Ne2i|Ne3i|Ne4i|NePa|NePaN
+  type atom = SvV|Sv1|Sv2i|Sv3i|Sv4i|NeP|NeAcqPc|NeRel|Ne1|Ne2|Ne3|Ne4|Ne2i|Ne3i|Ne4i|NePa|NePaN
 
   let fold_neon f r = r |>
     f NeAcqPc |> f NeRel |>
@@ -69,26 +70,35 @@ module SIMD = struct
     f Ne1 |> f Ne2 |> f Ne3 |> f Ne4 |>
     f Ne2i |> f Ne3i |> f Ne4i
 
+  let fold_sve f r = r |>
+    f SvV  |> f Sv1 |>
+    f Sv2i |> f Sv3i |> f Sv4i
+
   let nregs = function
-    | Ne1 -> 1
-    | Ne2 | Ne2i -> 2
-    | Ne3 | Ne3i -> 3
-    | Ne4 | Ne4i -> 4
+    | SvV | Sv1 | Ne1 -> 1
+    | Sv2i | Ne2 | Ne2i -> 2
+    | Sv3i | Ne3 | Ne3i -> 3
+    | Sv4i | Ne4 | Ne4i -> 4
     | _ -> 1
 
   let nelements = function
+    | SvV|Sv1|Sv2i|Sv3i|Sv4i
     | Ne1|Ne2|Ne2i|Ne3|Ne3i|Ne4|Ne4i -> 4
     | NePa|NePaN -> 2
     | NeP | NeAcqPc | NeRel -> 1
 
   let pp_opt = function
+    | Sv2i | Sv3i | Sv4i
     | Ne2i | Ne3i | Ne4i -> "i"
     | _ -> ""
 
   let pp n =
     match n with
     | Ne1 | Ne2 | Ne3 | Ne4 | Ne2i | Ne3i | Ne4i ->
        Printf.sprintf "Ne%i%s" (nregs n) (pp_opt n)
+    | Sv1 | Sv2i | Sv3i | Sv4i ->
+       Printf.sprintf "Sv%i%s" (nregs n) (pp_opt n)
+    | SvV -> "SvV"
     | NePa -> "NePa"
     | NePaN -> "NePaN"
     | NeP -> "NeP"
@@ -107,9 +117,10 @@ module SIMD = struct
     for k = 0 to sz-1 do
       for i=0 to el-1 do
         let j = match n with
-          | Ne2i | Ne3i | Ne4i -> k+i*sz
+          | Sv2i | Sv3i | Sv4i | Ne2i | Ne3i | Ne4i -> k+i*sz
           | NeP | NeAcqPc | NeRel | NePa | NePaN
-          | Ne1 | Ne2 | Ne3 | Ne4 -> i+k*el
+          | Ne1 | Ne2 | Ne3 | Ne4
+          | SvV | Sv1 -> i+k*el
         in
        v.(j) <- start+k
       done
@@ -120,9 +131,10 @@ module SIMD = struct
     let el = nelements n in
     let sz = nregs n in
     let access r k = match n with
-      | Ne2i | Ne3i | Ne4i -> sz*k + r
+      | Sv2i | Sv3i | Sv4i | Ne2i | Ne3i | Ne4i -> sz*k + r
       | NeP | NeAcqPc | NeRel | NePa | NePaN
-      | Ne1 | Ne2 | Ne3 | Ne4 -> el*r + k
+      | Ne1 | Ne2 | Ne3 | Ne4
+      | SvV | Sv1 -> el*r + k
     in
     let rec reg r k =
       if k >= el then []
@@ -335,6 +347,12 @@ let is_ifetch a = match a with
      else
        fun _ r -> r
 
+   let fold_sve =
+     if do_sve then
+       fun f -> SIMD.fold_sve (fun n -> f (Neon n))
+     else
+       fun _ r -> r
+
       let fold_pair f r =
         if do_mixed then r
         else
@@ -357,6 +375,7 @@ let is_ifetch a = match a with
      let r = fold_morello f r in
      let r = fold_tag f r in
      let r = fold_neon f r in
+     let r = fold_sve f r in
      let r = fold_pair f r in
      let r = fold_acc_opt None f r in
      let r =
@@ -456,10 +475,10 @@ let is_ifetch a = match a with
      function
      | NeP | NeAcqPc | NeRel -> 1
      | NePa | NePaN -> 2
-     | Ne1 -> 4
-     | Ne2 | Ne2i -> 8
-     | Ne3 | Ne3i -> 12
-     | Ne4 | Ne4i -> 16
+     | SvV | Sv1  | Ne1 -> 4
+     | Sv2i | Ne2 | Ne2i -> 8
+     | Sv3i | Ne3 | Ne3i -> 12
+     | Sv4i | Ne4 | Ne4i -> 16
 
    let atom_to_bank = function
    | Tag,None -> Code.Tag
@@ -866,6 +885,7 @@ include
 
       type special = reg
       let specials = vregs
+      let specials2 = pregs
     end)
 
 end