Improve code generation for bounds checks.

src/x64/lithium-codegen-x64.cc

Index: src/x64/lithium-codegen-x64.cc
diff --git a/src/x64/lithium-codegen-x64.cc b/src/x64/lithium-codegen-x64.cc
index 837bbcd0a55d77c8b45b54053ba31326ef9aac2a..0cc8d16aab3210ddc42236c5486d85248d9f7943 100644
--- a/src/x64/lithium-codegen-x64.cc
+++ b/src/x64/lithium-codegen-x64.cc
@@ -4140,65 +4140,64 @@ void LCodeGen::DoStoreNamedGeneric(LStoreNamedGeneric* instr) {
 }
 
 
-void LCodeGen::ApplyCheckIf(Condition cc, LBoundsCheck* check) {
-  if (FLAG_debug_code && check->hydrogen()->skip_check()) {
-    Label done;
-    __ j(NegateCondition(cc), &done, Label::kNear);
-    __ int3();
-    __ bind(&done);
-  } else {
-    DeoptimizeIf(cc, check->environment());
-  }
-}
-
-
 void LCodeGen::DoBoundsCheck(LBoundsCheck* instr) {
-  HBoundsCheck* hinstr = instr->hydrogen();
-  if (hinstr->skip_check()) return;
-
-  Representation representation = hinstr->length()->representation();
-  ASSERT(representation.Equals(hinstr->index()->representation()));
+  Representation representation = instr->hydrogen()->length()->representation();
+  ASSERT(representation.Equals(instr->hydrogen()->index()->representation()));
   ASSERT(representation.IsSmiOrInteger32());
 
-  if (instr->length()->IsRegister()) {
-    Register reg = ToRegister(instr->length());
-
-    if (instr->index()->IsConstantOperand()) {
-      int32_t constant_index =
-          ToInteger32(LConstantOperand::cast(instr->index()));
+  Condition cc = instr->hydrogen()->allow_equality() ? below : below_equal;
+  if (instr->length()->IsConstantOperand()) {
+    int32_t length = ToInteger32(LConstantOperand::cast(instr->length()));
+    Register index = ToRegister(instr->index());
+    if (representation.IsSmi()) {
+      __ Cmp(index, Smi::FromInt(length));
+    } else {
+      __ cmpl(index, Immediate(length));
+    }
+    cc = ReverseCondition(cc);
+  } else if (instr->index()->IsConstantOperand()) {
+    int32_t index = ToInteger32(LConstantOperand::cast(instr->index()));
+    if (instr->length()->IsRegister()) {
+      Register length = ToRegister(instr->length());
       if (representation.IsSmi()) {
-        __ Cmp(reg, Smi::FromInt(constant_index));
+        __ Cmp(length, Smi::FromInt(index));
       } else {
-        __ cmpl(reg, Immediate(constant_index));
+        __ cmpl(length, Immediate(index));
       }
     } else {
-      Register reg2 = ToRegister(instr->index());
+      Operand length = ToOperand(instr->length());
       if (representation.IsSmi()) {
-        __ cmpp(reg, reg2);
+        __ Cmp(length, Smi::FromInt(index));
       } else {
-        __ cmpl(reg, reg2);
+        __ cmpl(length, Immediate(index));
       }
     }
   } else {
-    Operand length = ToOperand(instr->length());
-    if (instr->index()->IsConstantOperand()) {
-      int32_t constant_index =
-          ToInteger32(LConstantOperand::cast(instr->index()));
+    Register index = ToRegister(instr->index());
+    if (instr->length()->IsRegister()) {
+      Register length = ToRegister(instr->length());
       if (representation.IsSmi()) {
-        __ Cmp(length, Smi::FromInt(constant_index));
+        __ cmpp(length, index);
       } else {
-        __ cmpl(length, Immediate(constant_index));
+        __ cmpl(length, index);
       }
     } else {
+      Operand length = ToOperand(instr->length());
       if (representation.IsSmi()) {
-        __ cmpp(length, ToRegister(instr->index()));
+        __ cmpp(length, index);
       } else {
-        __ cmpl(length, ToRegister(instr->index()));
+        __ cmpl(length, index);
       }
     }
   }
-  Condition condition = hinstr->allow_equality() ? below : below_equal;
-  ApplyCheckIf(condition, instr);
+  if (FLAG_debug_code && instr->hydrogen()->skip_check()) {
+    Label done;
+    __ j(NegateCondition(cc), &done, Label::kNear);
+    __ int3();
+    __ bind(&done);
+  } else {
+    DeoptimizeIf(cc, instr->environment());
+  }
 }