[x64] Zero/sign-extend loads to 64-bit registers.

Before this change we would first load an 8/16/32-bit value from memory into a 32-bit register, then zero/sign-extend from that register to a 64-bit one. Now we replace that pattern with a single movsx/movzx.

Ported from http://crrev.com/2183923003

R=bmeurer@chromium.org

Committed: https://crrev.com/4abecb7a27bd5fa073d0ff5fadb0c2bb248ef9f4
Review-Url: https://codereview.chromium.org/2220483003
Cr-Original-Commit-Position: refs/heads/master@{#38388}
Cr-Commit-Position: refs/heads/master@{#38428}

src/compiler/x64/code-generator-x64.cc

@@ -1754,6 +1754,13 @@ CodeGenerator::CodeGenResult CodeGenerator::AssembleArchInstruction(
       ASSEMBLE_MOVX(movzxbl);
       __ AssertZeroExtended(i.OutputRegister());
       break;
+    case kX64Movsxbq:
+      ASSEMBLE_MOVX(movsxbq);
+      break;
+    case kX64Movzxbq:
+      ASSEMBLE_MOVX(movzxbq);
+      __ AssertZeroExtended(i.OutputRegister());
+      break;
     case kX64Movb: {
       size_t index = 0;
       Operand operand = i.MemoryOperand(&index);
@@ -1772,6 +1779,13 @@ CodeGenerator::CodeGenResult CodeGenerator::AssembleArchInstruction(
       ASSEMBLE_MOVX(movzxwl);
       __ AssertZeroExtended(i.OutputRegister());
       break;
+    case kX64Movsxwq:
+      ASSEMBLE_MOVX(movsxwq);
+      break;
+    case kX64Movzxwq:
+      ASSEMBLE_MOVX(movzxwq);
+      __ AssertZeroExtended(i.OutputRegister());
+      break;
     case kX64Movw: {
       size_t index = 0;
       Operand operand = i.MemoryOperand(&index);

src/compiler/x64/instruction-codes-x64.h

@@ -117,9 +117,13 @@ namespace compiler {
   V(AVXFloat32Neg)                 \
   V(X64Movsxbl)                    \
   V(X64Movzxbl)                    \
+  V(X64Movsxbq)                    \
+  V(X64Movzxbq)                    \
   V(X64Movb)                       \
   V(X64Movsxwl)                    \
   V(X64Movzxwl)                    \
+  V(X64Movsxwq)                    \
+  V(X64Movzxwq)                    \
   V(X64Movw)                       \
   V(X64Movl)                       \
   V(X64Movsxlq)                    \

src/compiler/x64/instruction-scheduler-x64.cc

@@ -131,8 +131,12 @@ int InstructionScheduler::GetTargetInstructionFlags(
 
     case kX64Movsxbl:
     case kX64Movzxbl:
+    case kX64Movsxbq:
+    case kX64Movzxbq:
     case kX64Movsxwl:
     case kX64Movzxwl:
+    case kX64Movsxwq:
+    case kX64Movzxwq:
     case kX64Movsxlq:
       DCHECK(instr->InputCount() >= 1);
       return instr->InputAt(0)->IsRegister() ? kNoOpcodeFlags

src/compiler/x64/instruction-selector-x64.cc

@@ -1112,7 +1112,36 @@ void InstructionSelector::VisitTryTruncateFloat64ToUint64(Node* node) {
 
 void InstructionSelector::VisitChangeInt32ToInt64(Node* node) {
   X64OperandGenerator g(this);
-  Emit(kX64Movsxlq, g.DefineAsRegister(node), g.Use(node->InputAt(0)));
+  Node* const value = node->InputAt(0);
+  if (value->opcode() == IrOpcode::kLoad && CanCover(node, value)) {
+    LoadRepresentation load_rep = LoadRepresentationOf(value->op());
+    MachineRepresentation rep = load_rep.representation();
+    InstructionCode opcode = kArchNop;
+    switch (rep) {
+      case MachineRepresentation::kBit:  // Fall through.
+      case MachineRepresentation::kWord8:
+        opcode = load_rep.IsSigned() ? kX64Movsxbq : kX64Movzxbq;
+        break;
+      case MachineRepresentation::kWord16:
+        opcode = load_rep.IsSigned() ? kX64Movsxwq : kX64Movzxwq;
+        break;
+      case MachineRepresentation::kWord32:
+        opcode = load_rep.IsSigned() ? kX64Movsxlq : kX64Movl;
+        break;
+      default:
+        UNREACHABLE();
+        return;
+    }
+    InstructionOperand outputs[] = {g.DefineAsRegister(node)};
+    size_t input_count = 0;
+    InstructionOperand inputs[3];
+    AddressingMode mode = g.GetEffectiveAddressMemoryOperand(
+        node->InputAt(0), inputs, &input_count);
+    opcode |= AddressingModeField::encode(mode);
+    Emit(opcode, 1, outputs, input_count, inputs);
+  } else {
+    Emit(kX64Movsxlq, g.DefineAsRegister(node), g.Use(node->InputAt(0)));
+  }
 }
 
 

src/x64/assembler-x64.cc

@@ -1586,6 +1586,13 @@ void Assembler::movsxbq(Register dst, const Operand& src) {
   emit_operand(dst, src);
 }
 
+void Assembler::movsxbq(Register dst, Register src) {
+  EnsureSpace ensure_space(this);
+  emit_rex_64(dst, src);
+  emit(0x0F);
+  emit(0xBE);
+  emit_modrm(dst, src);
+}
 
 void Assembler::movsxwl(Register dst, Register src) {
   EnsureSpace ensure_space(this);
@@ -1613,6 +1620,13 @@ void Assembler::movsxwq(Register dst, const Operand& src) {
   emit_operand(dst, src);
 }
 
+void Assembler::movsxwq(Register dst, Register src) {
+  EnsureSpace ensure_space(this);
+  emit_rex_64(dst, src);
+  emit(0x0F);
+  emit(0xBF);
+  emit_modrm(dst, src);
+}
 
 void Assembler::movsxlq(Register dst, Register src) {
   EnsureSpace ensure_space(this);

src/x64/assembler-x64.h

@@ -708,9 +708,11 @@ class Assembler : public AssemblerBase {
 
   void movsxbl(Register dst, Register src);
   void movsxbl(Register dst, const Operand& src);
+  void movsxbq(Register dst, Register src);
   void movsxbq(Register dst, const Operand& src);
   void movsxwl(Register dst, Register src);
   void movsxwl(Register dst, const Operand& src);
+  void movsxwq(Register dst, Register src);
   void movsxwq(Register dst, const Operand& src);
   void movsxlq(Register dst, Register src);
   void movsxlq(Register dst, const Operand& src);

test/unittests/compiler/x64/instruction-selector-x64-unittest.cc

@@ -33,7 +33,6 @@ TEST_F(InstructionSelectorTest, ChangeInt32ToInt64WithParameter) {
   EXPECT_EQ(kX64Movsxlq, s[0]->arch_opcode());
 }
 
-
 TEST_F(InstructionSelectorTest, ChangeUint32ToFloat64WithParameter) {
   StreamBuilder m(this, MachineType::Float64(), MachineType::Uint32());
   m.Return(m.ChangeUint32ToFloat64(m.Parameter(0)));
@@ -71,6 +70,41 @@ TEST_F(InstructionSelectorTest, TruncateInt64ToInt32WithParameter) {
   EXPECT_EQ(kX64Movl, s[0]->arch_opcode());
 }
 
+namespace {
+struct LoadWithToInt64Extension {
+  MachineType type;
+  ArchOpcode expected_opcode;
+};
+
+std::ostream& operator<<(std::ostream& os,
+                         const LoadWithToInt64Extension& i32toi64) {
+  return os << i32toi64.type;
+}
+
+static const LoadWithToInt64Extension kLoadWithToInt64Extensions[] = {
+    {MachineType::Int8(), kX64Movsxbq},
+    {MachineType::Uint8(), kX64Movzxbq},
+    {MachineType::Int16(), kX64Movsxwq},
+    {MachineType::Uint16(), kX64Movzxwq},
+    {MachineType::Int32(), kX64Movsxlq}};
+
+}  // namespace
+
+typedef InstructionSelectorTestWithParam<LoadWithToInt64Extension>
+    InstructionSelectorChangeInt32ToInt64Test;
+
+TEST_P(InstructionSelectorChangeInt32ToInt64Test, ChangeInt32ToInt64WithLoad) {
+  const LoadWithToInt64Extension extension = GetParam();
+  StreamBuilder m(this, MachineType::Int64(), MachineType::Pointer());
+  m.Return(m.ChangeInt32ToInt64(m.Load(extension.type, m.Parameter(0))));
+  Stream s = m.Build();
+  ASSERT_EQ(1U, s.size());
+  EXPECT_EQ(extension.expected_opcode, s[0]->arch_opcode());
+}
+
+INSTANTIATE_TEST_CASE_P(InstructionSelectorTest,
+                        InstructionSelectorChangeInt32ToInt64Test,
+                        ::testing::ValuesIn(kLoadWithToInt64Extensions));
 
 // -----------------------------------------------------------------------------
 // Loads and stores