[x64] 64-bit shift left by 32 or more covers sign/zero extend.

TEST=unittests
R=jarin@chromium.org

Review URL: https://codereview.chromium.org/704703002

Cr-Commit-Position: refs/heads/master@{#25123}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25123 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

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

@@ -320,6 +320,17 @@ void InstructionSelector::VisitWord32Shl(Node* node) {
 
 
 void InstructionSelector::VisitWord64Shl(Node* node) {
+  X64OperandGenerator g(this);
+  Int64BinopMatcher m(node);
+  if ((m.left().IsChangeInt32ToInt64() || m.left().IsChangeUint32ToUint64()) &&
+      m.right().IsInRange(32, 63)) {
+    // There's no need to sign/zero-extend to 64-bit if we shift out the upper
+    // 32 bits anyway.
+    Emit(kX64Shl, g.DefineSameAsFirst(node),
+         g.UseRegister(m.left().node()->InputAt(0)),
+         g.UseImmediate(m.right().node()));
+    return;
+  }
   VisitWord64Shift(this, node, kX64Shl);
 }
 

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

@@ -323,6 +323,48 @@ TEST_F(InstructionSelectorTest, Uint32MulHigh) {
   EXPECT_TRUE(s.IsFixed(s[0]->OutputAt(0), rdx));
 }
 
+
+// -----------------------------------------------------------------------------
+// Word64Shl.
+
+
+TEST_F(InstructionSelectorTest, Word64ShlWithChangeInt32ToInt64) {
+  TRACED_FORRANGE(int64_t, x, 32, 63) {
+    StreamBuilder m(this, kMachInt64, kMachInt32);
+    Node* const p0 = m.Parameter(0);
+    Node* const n = m.Word64Shl(m.ChangeInt32ToInt64(p0), m.Int64Constant(x));
+    m.Return(n);
+    Stream s = m.Build();
+    ASSERT_EQ(1U, s.size());
+    EXPECT_EQ(kX64Shl, s[0]->arch_opcode());
+    ASSERT_EQ(2U, s[0]->InputCount());
+    EXPECT_EQ(s.ToVreg(p0), s.ToVreg(s[0]->InputAt(0)));
+    EXPECT_EQ(x, s.ToInt32(s[0]->InputAt(1)));
+    ASSERT_EQ(1U, s[0]->OutputCount());
+    EXPECT_TRUE(s.IsSameAsFirst(s[0]->Output()));
+    EXPECT_EQ(s.ToVreg(n), s.ToVreg(s[0]->Output()));
+  }
+}
+
+
+TEST_F(InstructionSelectorTest, Word64ShlWithChangeUint32ToUint64) {
+  TRACED_FORRANGE(int64_t, x, 32, 63) {
+    StreamBuilder m(this, kMachInt64, kMachUint32);
+    Node* const p0 = m.Parameter(0);
+    Node* const n = m.Word64Shl(m.ChangeUint32ToUint64(p0), m.Int64Constant(x));
+    m.Return(n);
+    Stream s = m.Build();
+    ASSERT_EQ(1U, s.size());
+    EXPECT_EQ(kX64Shl, s[0]->arch_opcode());
+    ASSERT_EQ(2U, s[0]->InputCount());
+    EXPECT_EQ(s.ToVreg(p0), s.ToVreg(s[0]->InputAt(0)));
+    EXPECT_EQ(x, s.ToInt32(s[0]->InputAt(1)));
+    ASSERT_EQ(1U, s[0]->OutputCount());
+    EXPECT_TRUE(s.IsSameAsFirst(s[0]->Output()));
+    EXPECT_EQ(s.ToVreg(n), s.ToVreg(s[0]->Output()));
+  }
+}
+
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8