[csa] Make CSA::TaggedEqual use WordEqual

Similar to https://crrev.com/c/1781047, WordEqual already does the right
truncation in the instruction selector.

Bug: v8:8948
Change-Id: I92e74bafab6a467aeca1570494e9044f9cf18c46
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1781049
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63504}

src/codegen/code-stub-assembler.h

@@ -470,32 +470,16 @@ class V8_EXPORT_PRIVATE CodeStubAssembler
 
   TNode<BoolT> TaggedEqual(TNode<UnionT<Object, MaybeObject>> a,
                            TNode<UnionT<Object, MaybeObject>> b) {
-    // We use very sketchy looking ReinterpretCasts here to avoid adding bit
-    // casts (which mess with GVN since they introduce themselves into the
-    // effect chain). It happens to be safe here, but don't try this at home!
-    if (kTaggedSize == kInt64Size) {
+    // In pointer-compressed architectures, the instruction selector will narrow
+    // this comparison to a 32-bit one.
     return WordEqual(ReinterpretCast<WordT>(a), ReinterpretCast<WordT>(b));
-    } else {
-      DCHECK_EQ(kTaggedSize, kInt32Size);
-      // These casts will also truncate under pointer compression.
-      return Word32Equal(ReinterpretCast<Word32T>(a),
-                         ReinterpretCast<Word32T>(b));
-    }
   }
 
   TNode<BoolT> TaggedNotEqual(TNode<UnionT<Object, MaybeObject>> a,
                               TNode<UnionT<Object, MaybeObject>> b) {
-    // We use very sketchy looking ReinterpretCasts here to avoid adding bit
-    // casts (which mess with GVN since they introduce themselves into the
-    // effect chain). It happens to be safe here, but don't try this at home!
-    if (kTaggedSize == kInt64Size) {
+    // In pointer-compressed architectures, the instruction selector will narrow
+    // this comparison to a 32-bit one.
     return WordNotEqual(ReinterpretCast<WordT>(a), ReinterpretCast<WordT>(b));
-    } else {
-      DCHECK_EQ(kTaggedSize, kInt32Size);
-      // These casts will also truncate under pointer compression.
-      return Word32NotEqual(ReinterpretCast<Word32T>(a),
-                            ReinterpretCast<Word32T>(b));
-    }
   }
 
   TNode<Object> NoContextConstant();

src/compiler/machine-graph-verifier.cc

@@ -462,13 +462,8 @@ class MachineRepresentationChecker {
             break;
           case IrOpcode::kWord64Equal:
             if (Is64()) {
-              if (COMPRESS_POINTERS_BOOL) {
-                CheckValueInputForInt64Op(node, 0);
-                CheckValueInputForInt64Op(node, 1);
-              } else {
               CheckValueInputIsTaggedOrPointer(node, 0);
               CheckValueInputIsTaggedOrPointer(node, 1);
-              }
               if (!is_stub_) {
                 CheckValueInputRepresentationIs(
                     node, 1, inferrer_->GetRepresentation(node->InputAt(0)));
@@ -519,17 +514,10 @@ class MachineRepresentationChecker {
                 CheckValueInputRepresentationIs(
                     node, 1, inferrer_->GetRepresentation(node->InputAt(0)));
               }
-            } else {
-              if (COMPRESS_POINTERS_BOOL) {
-                // We explicitly allow 64-bit tagged values into Word32Equal,
-                // for truncating tagged pointer comparison.
-                CheckValueIsCompressedOrTaggedOrInt32(node, 0);
-                CheckValueIsCompressedOrTaggedOrInt32(node, 0);
             } else {
               CheckValueIsCompressedOrInt32(node, 0);
               CheckValueIsCompressedOrInt32(node, 1);
             }
-            }
             break;
 
           case IrOpcode::kInt32LessThan:
@@ -896,34 +884,6 @@ class MachineRepresentationChecker {
     FATAL("%s", str.str().c_str());
   }
 
-  void CheckValueIsCompressedOrTaggedOrInt32(Node const* node, int index) {
-    Node const* input = node->InputAt(index);
-    switch (inferrer_->GetRepresentation(input)) {
-      case MachineRepresentation::kBit:
-      case MachineRepresentation::kWord8:
-      case MachineRepresentation::kWord16:
-      case MachineRepresentation::kWord32:
-        return;
-      case MachineRepresentation::kTagged:
-      case MachineRepresentation::kTaggedPointer:
-      case MachineRepresentation::kTaggedSigned:
-        return;
-      case MachineRepresentation::kCompressed:
-      case MachineRepresentation::kCompressedSigned:
-      case MachineRepresentation::kCompressedPointer:
-        return;
-      default:
-        break;
-    }
-    std::ostringstream str;
-    str << "TypeError: node #" << node->id() << ":" << *node->op()
-        << " uses node #" << input->id() << ":" << *input->op()
-        << " which doesn't have a compressed, tagged, or int32-compatible "
-           "representation.";
-    PrintDebugHelp(str, node);
-    FATAL("%s", str.str().c_str());
-  }
-
   void CheckValueInputForInt64Op(Node const* node, int index) {
     Node const* input = node->InputAt(index);
     MachineRepresentation input_representation =