[ptr-compr] Specialize CompressedSigned -> Word32 conversion

This CL aims to address the regressions that we saw in Octane 2.1,
particularly in the DeltaBlue test.

This CL brings a 5% improvement in said test by doing
CompressedSigned -> Word32 conversion (instead of
CompressedSigned -> TaggedSigned -> Word32).

There seems to be room for optimizations doing more specialized conversions
regarding representation changes.

Cq-Include-Trybots: luci.v8.try:v8_linux64_pointer_compression_rel_ng
Cq-Include-Trybots: luci.v8.try:v8_linux64_arm64_pointer_compression_rel_ng
Bug: v8:7703
Change-Id: I24e5b6c06436fdda9fa6a1ac4699dc55c3d67abd
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1684075
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62557}

src/compiler/effect-control-linearizer.cc

@@ -58,6 +58,7 @@ class EffectControlLinearizer {
   Node* LowerChangeUint64ToTagged(Node* node);
   Node* LowerChangeFloat64ToTagged(Node* node);
   Node* LowerChangeFloat64ToTaggedPointer(Node* node);
+  Node* LowerChangeCompressedSignedToInt32(Node* node);
   Node* LowerChangeTaggedSignedToInt32(Node* node);
   Node* LowerChangeTaggedSignedToInt64(Node* node);
   Node* LowerChangeTaggedToBit(Node* node);
@@ -228,6 +229,7 @@ class EffectControlLinearizer {
   Node* ChangeUint32ToUintPtr(Node* value);
   Node* ChangeUint32ToSmi(Node* value);
   Node* ChangeSmiToIntPtr(Node* value);
+  Node* ChangeCompressedSmiToInt32(Node* value);
   Node* ChangeSmiToInt32(Node* value);
   Node* ChangeSmiToInt64(Node* value);
   Node* ObjectIsSmi(Node* value);
@@ -854,6 +856,9 @@ bool EffectControlLinearizer::TryWireInStateEffect(Node* node,
     case IrOpcode::kChangeFloat64ToTaggedPointer:
       result = LowerChangeFloat64ToTaggedPointer(node);
       break;
+    case IrOpcode::kChangeCompressedSignedToInt32:
+      result = LowerChangeCompressedSignedToInt32(node);
+      break;
     case IrOpcode::kChangeTaggedSignedToInt32:
       result = LowerChangeTaggedSignedToInt32(node);
       break;
@@ -1485,6 +1490,11 @@ Node* EffectControlLinearizer::LowerChangeTaggedSignedToInt32(Node* node) {
   return ChangeSmiToInt32(value);
 }
 
+Node* EffectControlLinearizer::LowerChangeCompressedSignedToInt32(Node* node) {
+  Node* value = node->InputAt(0);
+  return ChangeCompressedSmiToInt32(value);
+}
+
 Node* EffectControlLinearizer::LowerChangeTaggedSignedToInt64(Node* node) {
   Node* value = node->InputAt(0);
   return ChangeSmiToInt64(value);
@@ -4459,6 +4469,11 @@ Node* EffectControlLinearizer::ChangeSmiToInt32(Node* value) {
   return ChangeSmiToIntPtr(value);
 }
 
+Node* EffectControlLinearizer::ChangeCompressedSmiToInt32(Node* value) {
+  CHECK(machine()->Is64() && SmiValuesAre31Bits());
+  return __ Word32Sar(value, SmiShiftBitsConstant());
+}
+
 Node* EffectControlLinearizer::ChangeSmiToInt64(Node* value) {
   CHECK(machine()->Is64());
   return ChangeSmiToIntPtr(value);

src/compiler/opcodes.h

@@ -232,6 +232,7 @@
 
 // Opcodes for VirtuaMachine-level operators.
 #define SIMPLIFIED_CHANGE_OP_LIST(V) \
+  V(ChangeCompressedSignedToInt32)   \
   V(ChangeTaggedSignedToInt32)       \
   V(ChangeTaggedSignedToInt64)       \
   V(ChangeTaggedToInt32)             \

src/compiler/representation-change.cc

@@ -1089,11 +1089,15 @@ Node* RepresentationChanger::GetWord32RepresentationFor(
                                       output_type, use_node, use_info);
   } else if (output_rep == MachineRepresentation::kCompressedSigned) {
     // TODO(v8:8977): Specialise here
-    op = machine()->ChangeCompressedSignedToTaggedSigned();
-    node = jsgraph()->graph()->NewNode(op, node);
-    return GetWord32RepresentationFor(node,
-                                      MachineRepresentation::kTaggedSigned,
-                                      output_type, use_node, use_info);
+    if (output_type.Is(Type::SignedSmall())) {
+      op = simplified()->ChangeCompressedSignedToInt32();
+    } else {
+      op = machine()->ChangeCompressedSignedToTaggedSigned();
+      node = jsgraph()->graph()->NewNode(op, node);
+      return GetWord32RepresentationFor(node,
+                                        MachineRepresentation::kTaggedSigned,
+                                        output_type, use_node, use_info);
+    }
   } else if (output_rep == MachineRepresentation::kCompressedPointer) {
     // TODO(v8:8977): Specialise here
     op = machine()->ChangeCompressedPointerToTaggedPointer();

src/compiler/simplified-operator.cc

@@ -720,6 +720,7 @@ bool operator==(CheckMinusZeroParameters const& lhs,
   V(PlainPrimitiveToNumber, Operator::kNoProperties, 1, 0)         \
   V(PlainPrimitiveToWord32, Operator::kNoProperties, 1, 0)         \
   V(PlainPrimitiveToFloat64, Operator::kNoProperties, 1, 0)        \
+  V(ChangeCompressedSignedToInt32, Operator::kNoProperties, 1, 0)  \
   V(ChangeTaggedSignedToInt32, Operator::kNoProperties, 1, 0)      \
   V(ChangeTaggedSignedToInt64, Operator::kNoProperties, 1, 0)      \
   V(ChangeTaggedToInt32, Operator::kNoProperties, 1, 0)            \

src/compiler/simplified-operator.h

@@ -695,6 +695,7 @@ class V8_EXPORT_PRIVATE SimplifiedOperatorBuilder final
   const Operator* PlainPrimitiveToWord32();
   const Operator* PlainPrimitiveToFloat64();
 
+  const Operator* ChangeCompressedSignedToInt32();
   const Operator* ChangeTaggedSignedToInt32();
   const Operator* ChangeTaggedSignedToInt64();
   const Operator* ChangeTaggedToInt32();

src/compiler/verifier.cc

@@ -1320,6 +1320,7 @@ void Verifier::Visitor::Check(Node* node, const AllNodes& all) {
       CheckNotTyped(node);
       break;
 
+    case IrOpcode::kChangeCompressedSignedToInt32:
     case IrOpcode::kChangeTaggedSignedToInt32: {
       // Signed32 /\ Tagged -> Signed32 /\ UntaggedInt32
       // TODO(neis): Activate once ChangeRepresentation works in typer.

test/unittests/compiler/simplified-operator-unittest.cc

@@ -53,6 +53,7 @@ const PureOperator kPureOperators[] = {
     PURE(NumberShiftRightLogical, Operator::kNoProperties, 2),
     PURE(NumberToInt32, Operator::kNoProperties, 1),
     PURE(NumberToUint32, Operator::kNoProperties, 1),
+    PURE(ChangeCompressedSignedToInt32, Operator::kNoProperties, 1),
     PURE(ChangeTaggedSignedToInt32, Operator::kNoProperties, 1),
     PURE(ChangeTaggedToInt32, Operator::kNoProperties, 1),
     PURE(ChangeTaggedToUint32, Operator::kNoProperties, 1),