PPC/s390: [wasm] Implement "atomic.fence" operator.

Port 4ca8b4dd

Original Commit Message:

    This adds decoding and compilation of the "atomic.fence" operator, which
    is intended to preserve the synchronization guarantees of higher-level
    languages.

    Unlike other atomic operators, it does not target a particular linear
    memory. It may occur in modules which declare no memory, or a non-shared
    memory, without causing a validation error.

    See proposal: https://github.com/WebAssembly/threads/pull/141
    See discussion: https://github.com/WebAssembly/threads/issues/140

R=mstarzinger@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com
BUG=v8:9452
LOG=N

Change-Id: Ib8ad24e65154d7555a47e537f81110be47f4d4de
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1710620
Commit-Queue: Milad Farazmand <miladfar@ca.ibm.com>
Reviewed-by: Junliang Yan <jyan@ca.ibm.com>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62850}

src/compiler/backend/ppc/code-generator-ppc.cc

@@ -1195,6 +1195,10 @@ CodeGenerator::CodeGenResult CodeGenerator::AssembleArchInstruction(
       }
       break;
     }
+    case kPPC_Sync: {
+      __ sync();
+      break;
+    }
     case kPPC_And:
       if (HasRegisterInput(instr, 1)) {
         __ and_(i.OutputRegister(), i.InputRegister(0), i.InputRegister(1),

src/compiler/backend/ppc/instruction-codes-ppc.h

@@ -13,6 +13,7 @@ namespace compiler {
 // Most opcodes specify a single instruction.
 #define TARGET_ARCH_OPCODE_LIST(V)   \
   V(PPC_Peek)                        \
+  V(PPC_Sync)                        \
   V(PPC_And)                         \
   V(PPC_AndComplement)               \
   V(PPC_Or)                          \

src/compiler/backend/ppc/instruction-scheduler-ppc.cc

@@ -143,6 +143,7 @@ int InstructionScheduler::GetTargetInstructionFlags(
     case kPPC_Push:
     case kPPC_PushFrame:
     case kPPC_StoreToStackSlot:
+    case kPPC_Sync:
       return kHasSideEffect;
 
     case kPPC_AtomicStoreUint8:

src/compiler/backend/ppc/instruction-selector-ppc.cc

@@ -1853,6 +1853,11 @@ void InstructionSelector::VisitFloat64InsertHighWord32(Node* node) {
        g.UseRegister(left), g.UseRegister(right));
 }
 
+void InstructionSelector::VisitMemoryBarrier(Node* node) {
+  PPCOperandGenerator g(this);
+  Emit(kPPC_Sync, g.NoOutput());
+}
+
 void InstructionSelector::VisitWord32AtomicLoad(Node* node) { VisitLoad(node); }
 
 void InstructionSelector::VisitWord64AtomicLoad(Node* node) { VisitLoad(node); }

src/compiler/backend/s390/instruction-selector-s390.cc

@@ -2198,6 +2198,11 @@ void InstructionSelector::EmitPrepareArguments(
   }
 }
 
+void InstructionSelector::VisitMemoryBarrier(Node* node) {
+  S390OperandGenerator g(this);
+  Emit(kArchNop, g.NoOutput());
+}
+
 bool InstructionSelector::IsTailCallAddressImmediate() { return false; }
 
 int InstructionSelector::GetTempsCountForTailCallFromJSFunction() { return 3; }