[ptr-compr] Generate TaggedEqual as Word32Equal of compressed values

... in both CSA code and TurboFan. This is a prerequisite for smi-corrupting
decompression.

The decompression eliminator changes is a workaround to ensure that the result
of comparisons of two constant Smis is still a constexpr (the failing test is
cctest/test-torque/TestLoadEliminationFixed). Better optimizations will be
landed in a follow-up CLs.

Bug: v8:9706
Change-Id: Ie2d90f6a7714aa749439e3f457d90d663d0efe49
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1815133Reviewed-by: Santiago Aboy Solanes <solanes@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63991}

src/codegen/arm64/macro-assembler-arm64.cc

@@ -295,7 +295,9 @@ void TurboAssembler::Mov(const Register& rd, const Operand& operand,
         } else if (RelocInfo::IsEmbeddedObjectMode(operand.ImmediateRMode())) {
           Handle<HeapObject> x(
               reinterpret_cast<Address*>(operand.ImmediateValue()));
-          IndirectLoadConstant(rd, x);
+          // TODO(v8:9706): Fix-it! This load will always uncompress the value
+          // even when we are loading a compressed embedded object.
+          IndirectLoadConstant(rd.X(), x);
           return;
         }
       }

src/codegen/code-stub-assembler.h

@@ -510,9 +510,12 @@ class V8_EXPORT_PRIVATE CodeStubAssembler
   uintptr_t ConstexprWordNot(uintptr_t a) { return ~a; }
 
   TNode<BoolT> TaggedEqual(TNode<AnyTaggedT> a, TNode<AnyTaggedT> b) {
-    // In pointer-compressed architectures, the instruction selector will narrow
-    // this comparison to a 32-bit one.
+#ifdef V8_COMPRESS_POINTERS
+    return Word32Equal(ChangeTaggedToCompressed(a),
+                       ChangeTaggedToCompressed(b));
+#else
     return WordEqual(ReinterpretCast<WordT>(a), ReinterpretCast<WordT>(b));
+#endif
   }
 
   TNode<BoolT> TaggedNotEqual(TNode<AnyTaggedT> a, TNode<AnyTaggedT> b) {

src/codegen/x64/macro-assembler-x64.cc

@@ -1461,6 +1461,8 @@ void TurboAssembler::Move(Register result, Handle<HeapObject> object,
                           RelocInfo::Mode rmode) {
   if (FLAG_embedded_builtins) {
     if (root_array_available_ && options().isolate_independent_code) {
+      // TODO(v8:9706): Fix-it! This load will always uncompress the value
+      // even when we are loading a compressed embedded object.
       IndirectLoadConstant(result, object);
       return;
     }

src/compiler/code-assembler.h

@@ -302,6 +302,7 @@ TNode<Float64T> Float64Add(TNode<Float64T> a, TNode<Float64T> b);
   V(ChangeInt32ToInt64, Int64T, Int32T)                        \
   V(ChangeUint32ToFloat64, Float64T, Word32T)                  \
   V(ChangeUint32ToUint64, Uint64T, Word32T)                    \
+  V(ChangeTaggedToCompressed, TaggedT, AnyTaggedT)             \
   V(BitcastInt32ToFloat32, Float32T, Word32T)                  \
   V(BitcastFloat32ToInt32, Uint32T, Float32T)                  \
   V(RoundFloat64ToInt32, Int32T, Float64T)                     \

src/compiler/decompression-elimination.cc

@@ -167,6 +167,42 @@ Reduction DecompressionElimination::ReduceTypedStateValues(Node* node) {
   return any_change ? Changed(node) : NoChange();
 }
 
+Reduction DecompressionElimination::ReduceWord32Equal(Node* node) {
+  DCHECK_EQ(node->opcode(), IrOpcode::kWord32Equal);
+
+  DCHECK_EQ(node->InputCount(), 2);
+  Node* lhs = node->InputAt(0);
+  Node* rhs = node->InputAt(1);
+
+  if (!IrOpcode::IsCompressOpcode(lhs->opcode()) ||
+      !IrOpcode::IsCompressOpcode(rhs->opcode())) {
+    return NoChange();
+  }
+  // Input nodes for compress operation.
+  lhs = lhs->InputAt(0);
+  rhs = rhs->InputAt(0);
+
+  bool changed = false;
+
+  if (lhs->opcode() == IrOpcode::kBitcastWordToTaggedSigned) {
+    Node* input = lhs->InputAt(0);
+    if (IsReducibleConstantOpcode(input->opcode())) {
+      node->ReplaceInput(0, GetCompressedConstant(input));
+      changed = true;
+    }
+  }
+
+  if (rhs->opcode() == IrOpcode::kBitcastWordToTaggedSigned) {
+    Node* input = rhs->InputAt(0);
+    if (IsReducibleConstantOpcode(input->opcode())) {
+      node->ReplaceInput(1, GetCompressedConstant(input));
+      changed = true;
+    }
+  }
+
+  return changed ? Changed(node) : NoChange();
+}
+
 Reduction DecompressionElimination::ReduceWord64Equal(Node* node) {
   DCHECK_EQ(node->opcode(), IrOpcode::kWord64Equal);
 
@@ -220,6 +256,8 @@ Reduction DecompressionElimination::Reduce(Node* node) {
       return ReducePhi(node);
     case IrOpcode::kTypedStateValues:
       return ReduceTypedStateValues(node);
+    case IrOpcode::kWord32Equal:
+      return ReduceWord32Equal(node);
     case IrOpcode::kWord64Equal:
       return ReduceWord64Equal(node);
     default:

src/compiler/decompression-elimination.h

@@ -65,6 +65,11 @@ class V8_EXPORT_PRIVATE DecompressionElimination final
   // value of that constant.
   Reduction ReduceWord64Equal(Node* node);
 
+  // This is a workaround for load elimination test.
+  // Replaces Compress -> BitcastWordToTaggedSigned -> ReducibleConstant
+  // to CompressedConstant on both inputs of Word32Equal operation.
+  Reduction ReduceWord32Equal(Node* node);
+
   Graph* graph() const { return graph_; }
   MachineOperatorBuilder* machine() const { return machine_; }
   CommonOperatorBuilder* common() const { return common_; }

src/compiler/graph-assembler.cc

@@ -99,7 +99,12 @@ Node* GraphAssembler::IntPtrEqual(Node* left, Node* right) {
 }
 
 Node* GraphAssembler::TaggedEqual(Node* left, Node* right) {
+#ifdef V8_COMPRESS_POINTERS
+  return Word32Equal(ChangeTaggedToCompressed(left),
+                     ChangeTaggedToCompressed(right));
+#else
   return WordEqual(left, right);
+#endif
 }
 
 Node* GraphAssembler::Float64RoundDown(Node* value) {

src/compiler/machine-graph-verifier.cc

@@ -461,7 +461,7 @@ class MachineRepresentationChecker {
             CheckValueInputForFloat64Op(node, 0);
             break;
           case IrOpcode::kWord64Equal:
-            if (Is64()) {
+            if (Is64() && !COMPRESS_POINTERS_BOOL) {
               CheckValueInputIsTaggedOrPointer(node, 0);
               CheckValueInputIsTaggedOrPointer(node, 1);
               if (!is_stub_) {