Avoid Unnecessary Smi Checks

src/arm/lithium-codegen-arm.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1888 matching lines @@
   __ ubfx(result, result, Map::kElementsKindShift, Map::kElementsKindBitCount);
 }
 
 
 void LCodeGen::DoValueOf(LValueOf* instr) {
   Register input = ToRegister(instr->value());
   Register result = ToRegister(instr->result());
   Register map = ToRegister(instr->temp());
   Label done;
 
-  // If the object is a smi return the object.
-  __ SmiTst(input);
-  __ Move(result, input, eq);
-  __ b(eq, &done);
+  if (!instr->hydrogen()->value()->IsHeapObject()) {
+    // If the object is a smi return the object.
+    __ SmiTst(input);
+    __ Move(result, input, eq);
+    __ b(eq, &done);
+  }
 
   // If the object is not a value type, return the object.
   __ CompareObjectType(input, map, map, JS_VALUE_TYPE);
   __ Move(result, input, ne);
   __ b(ne, &done);
   __ ldr(result, FieldMemOperand(input, JSValue::kValueOffset));
 
   __ bind(&done);
 }
 
@@ skipping 531 matching lines @@
 
   Condition true_cond =
       EmitIsObject(reg, temp1, false_label, true_label);
 
   EmitBranch(true_block, false_block, true_cond);
 }
 
 
 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);
+  }
   __ CompareObjectType(input, temp1, temp1, FIRST_NONSTRING_TYPE);
 
   return lt;
 }
 
 
 void LCodeGen::DoIsStringAndBranch(LIsStringAndBranch* instr) {
   Register reg = ToRegister(instr->value());
   Register temp1 = ToRegister(instr->temp());
 
   int true_block = chunk_->LookupDestination(instr->true_block_id());
   int false_block = chunk_->LookupDestination(instr->false_block_id());
   Label* false_label = chunk_->GetAssemblyLabel(false_block);
 
+  SmiCheck check_needed =
+      instr->hydrogen()->value()->IsHeapObject()
+          ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
   Condition true_cond =
-      EmitIsString(reg, temp1, false_label);
+      EmitIsString(reg, temp1, false_label, check_needed);
 
   EmitBranch(true_block, false_block, true_cond);
 }
 
 
 void LCodeGen::DoIsSmiAndBranch(LIsSmiAndBranch* instr) {
   int true_block = chunk_->LookupDestination(instr->true_block_id());
   int false_block = chunk_->LookupDestination(instr->false_block_id());
 
   Register input_reg = EmitLoadRegister(instr->value(), ip);
   __ SmiTst(input_reg);
   EmitBranch(true_block, false_block, eq);
 }
 
 
 void LCodeGen::DoIsUndetectableAndBranch(LIsUndetectableAndBranch* instr) {
   Register input = ToRegister(instr->value());
   Register temp = ToRegister(instr->temp());
 
   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));
+  }
   __ ldr(temp, FieldMemOperand(input, HeapObject::kMapOffset));
   __ ldrb(temp, FieldMemOperand(temp, Map::kBitFieldOffset));
   __ tst(temp, Operand(1 << Map::kIsUndetectable));
   EmitBranch(true_block, false_block, ne);
 }
 
 
 static Condition ComputeCompareCondition(Token::Value op) {
   switch (op) {
     case Token::EQ_STRICT:
@@ skipping 52 matching lines @@
 
 void LCodeGen::DoHasInstanceTypeAndBranch(LHasInstanceTypeAndBranch* instr) {
   Register scratch = scratch0();
   Register input = ToRegister(instr->value());
 
   int true_block = chunk_->LookupDestination(instr->true_block_id());
   int false_block = chunk_->LookupDestination(instr->false_block_id());
 
   Label* false_label = chunk_->GetAssemblyLabel(false_block);
 
-  __ JumpIfSmi(input, false_label);
+  if (!instr->hydrogen()->value()->IsHeapObject()) {
+    __ JumpIfSmi(input, false_label);
+  }
 
   __ CompareObjectType(input, scratch, scratch, TestType(instr->hydrogen()));
   EmitBranch(true_block, false_block, BranchCondition(instr->hydrogen()));
 }
 
 
 void LCodeGen::DoGetCachedArrayIndex(LGetCachedArrayIndex* instr) {
   Register input = ToRegister(instr->value());
   Register result = ToRegister(instr->result());
 
@@ skipping 424 matching lines @@
     __ cmp(scratch, ip);
     if (instr->hydrogen()->DeoptimizesOnHole()) {
       DeoptimizeIf(eq, instr->environment());
     } else {
       __ b(ne, &skip_assignment);
     }
   }
 
   __ str(value, target);
   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;
     __ RecordWriteContextSlot(context,
                               target.offset(),
                               value,
                               scratch,
                               GetLinkRegisterState(),
                               kSaveFPRegs,
                               EMIT_REMEMBERED_SET,
                               check_needed);
   }
 
@@ skipping 1221 matching lines @@
                           GetLinkRegisterState(),
                           kSaveFPRegs,
                           OMIT_REMEMBERED_SET,
                           OMIT_SMI_CHECK);
     }
   }
 
   // Do the store.
   Register value = ToRegister(instr->value());
   ASSERT(!object.is(value));
-  HType type = instr->hydrogen()->value()->type();
   SmiCheck check_needed =
-      type.IsHeapObject() ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
+      !instr->hydrogen()->value()->IsHeapObject()

[ulan, 2013/06/20 07:49:11]

Negate the condition to make it consistent with the other similar checks.

+          ? INLINE_SMI_CHECK : OMIT_SMI_CHECK;
   if (access.IsInobject()) {
     __ str(value, FieldMemOperand(object, offset));
     if (instr->hydrogen()->NeedsWriteBarrier()) {
       // Update the write barrier for the object for in-object properties.
       __ RecordWriteField(object,
                           offset,
                           value,
                           scratch,
                           GetLinkRegisterState(),
                           kSaveFPRegs,
@@ skipping 188 matching lines @@
     if (instr->hydrogen()->key()->representation().IsSmi()) {
       __ add(scratch, elements, Operand::PointerOffsetFromSmiKey(key));
     } else {
       __ add(scratch, elements, Operand(key, LSL, kPointerSizeLog2));
     }
     offset = FixedArray::OffsetOfElementAt(instr->additional_index());
   }
   __ str(value, FieldMemOperand(store_base, offset));
 
   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;
     // Compute address of modified element and store it into key register.
     __ add(key, store_base, Operand(offset - kHeapObjectTag));
     __ RecordWrite(elements,
                    key,
                    value,
                    GetLinkRegisterState(),
                    kSaveFPRegs,
                    EMIT_REMEMBERED_SET,
                    check_needed);
   }
@@ skipping 1390 matching lines @@
   __ sub(scratch, result, Operand::PointerOffsetFromSmiKey(index));
   __ ldr(result, FieldMemOperand(scratch,
                                  FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal