Avoid Unnecessary Smi 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 1dd27ac9bd7c7cdde01f51f4ac63778fcd9c187e..1df49ed79fd9061670de4b932b18eaacacb08a74 100644
--- a/src/x64/lithium-codegen-x64.cc
+++ b/src/x64/lithium-codegen-x64.cc
@@ -1612,8 +1612,11 @@ void LCodeGen::DoValueOf(LValueOf* instr) {
   Register result = ToRegister(instr->result());
   ASSERT(input.is(result));
   Label done;
-  // If the object is a smi return the object.
-  __ JumpIfSmi(input, &done, Label::kNear);
+
+  if (!instr->hydrogen()->value()->IsHeapObject()) {
+    // If the object is a smi return the object.
+    __ JumpIfSmi(input, &done, Label::kNear);
+  }
 
   // If the object is not a value type, return the object.
   __ CmpObjectType(input, JS_VALUE_TYPE, kScratchRegister);
@@ -2176,8 +2179,12 @@ void LCodeGen::DoIsObjectAndBranch(LIsObjectAndBranch* instr) {
 
 Condition LCodeGen::EmitIsString(Register input,
                                  Register temp1,
-                                 Label* is_not_string) {
-  __ JumpIfSmi(input, is_not_string);
+                                 Label* is_not_string,
+                                 SmiCheck check_needed = INLINE_SMI_CHECK) {
+  if (check_needed == INLINE_SMI_CHECK) {
+    __ JumpIfSmi(input, is_not_string);
+  }
+
   Condition cond =  masm_->IsObjectStringType(input, temp1, temp1);
 
   return cond;
@@ -2192,7 +2199,11 @@ void LCodeGen::DoIsStringAndBranch(LIsStringAndBranch* instr) {
   int false_block = chunk_->LookupDestination(instr->false_block_id());
   Label* false_label = chunk_->GetAssemblyLabel(false_block);
 
-  Condition true_cond = EmitIsString(reg, temp, false_label);
+  SmiCheck check_needed =
+      instr->hydrogen()->value()->IsHeapObject()
+          ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
+
+  Condition true_cond = EmitIsString(reg, temp, false_label, check_needed);
 
   EmitBranch(true_block, false_block, true_cond);
 }
@@ -2221,7 +2232,9 @@ void LCodeGen::DoIsUndetectableAndBranch(LIsUndetectableAndBranch* instr) {
   int true_block = chunk_->LookupDestination(instr->true_block_id());
   int false_block = chunk_->LookupDestination(instr->false_block_id());
 
-  __ JumpIfSmi(input, chunk_->GetAssemblyLabel(false_block));
+  if (!instr->hydrogen()->value()->IsHeapObject()) {
+    __ JumpIfSmi(input, chunk_->GetAssemblyLabel(false_block));
+  }
   __ movq(temp, FieldOperand(input, HeapObject::kMapOffset));
   __ testb(FieldOperand(temp, Map::kBitFieldOffset),
            Immediate(1 << Map::kIsUndetectable));
@@ -2272,7 +2285,9 @@ void LCodeGen::DoHasInstanceTypeAndBranch(LHasInstanceTypeAndBranch* instr) {
 
   Label* false_label = chunk_->GetAssemblyLabel(false_block);
 
-  __ JumpIfSmi(input, false_label);
+  if (!instr->hydrogen()->value()->IsHeapObject()) {
+    __ JumpIfSmi(input, false_label);
+  }
 
   __ CmpObjectType(input, TestType(instr->hydrogen()), kScratchRegister);
   EmitBranch(true_block, false_block, BranchCondition(instr->hydrogen()));
@@ -2692,9 +2707,9 @@ void LCodeGen::DoStoreContextSlot(LStoreContextSlot* instr) {
   __ movq(target, value);
 
   if (instr->hydrogen()->NeedsWriteBarrier()) {
-    HType type = instr->hydrogen()->value()->type();
     SmiCheck check_needed =
-        type.IsHeapObject() ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
+      instr->hydrogen()->value()->IsHeapObject()
+          ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
     int offset = Context::SlotOffset(instr->slot_index());
     Register scratch = ToRegister(instr->temp());
     __ RecordWriteContextSlot(context,
@@ -4020,9 +4035,9 @@ void LCodeGen::DoStoreNamedField(LStoreNamedField* instr) {
   }
 
   // Do the store.
-  HType type = instr->hydrogen()->value()->type();
   SmiCheck check_needed =
-      type.IsHeapObject() ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
+      instr->hydrogen()->value()->IsHeapObject()
+          ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
 
   Register write_register = object;
   if (!access.IsInobject()) {
@@ -4261,9 +4276,9 @@ void LCodeGen::DoStoreKeyedFixedArray(LStoreKeyed* instr) {
     ASSERT(instr->value()->IsRegister());
     Register value = ToRegister(instr->value());
     ASSERT(!instr->key()->IsConstantOperand());
-    HType type = instr->hydrogen()->value()->type();
     SmiCheck check_needed =
-        type.IsHeapObject() ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
+        instr->hydrogen()->value()->IsHeapObject()
+            ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
     // Compute address of modified element and store it into key register.
     Register key_reg(ToRegister(key));
     __ lea(key_reg, operand);