Optimize Smi keys for KeyedLoads

src/ia32/lithium-codegen-ia32.cc

Index: src/ia32/lithium-codegen-ia32.cc
diff --git a/src/ia32/lithium-codegen-ia32.cc b/src/ia32/lithium-codegen-ia32.cc
index 6317a54a2b400385c2c75ff3c59b6fac8ca36deb..ff569b37073b1cdfcc85d55677dc22d1323cb772 100644
--- a/src/ia32/lithium-codegen-ia32.cc
+++ b/src/ia32/lithium-codegen-ia32.cc
@@ -2648,6 +2648,7 @@ void LCodeGen::DoLoadKeyedFastElement(LLoadKeyedFastElement* instr) {
   __ mov(result,
          BuildFastArrayOperand(instr->elements(),
                                instr->key(),
+                               instr->hydrogen()->key()->representation(),
                                FAST_ELEMENTS,
                                FixedArray::kHeaderSize - kHeapObjectTag,
                                instr->additional_index()));
@@ -2674,6 +2675,7 @@ void LCodeGen::DoLoadKeyedFastDoubleElement(
         sizeof(kHoleNanLower32);
     Operand hole_check_operand = BuildFastArrayOperand(
         instr->elements(), instr->key(),
+        instr->hydrogen()->key()->representation(),
         FAST_DOUBLE_ELEMENTS,
         offset,
         instr->additional_index());
@@ -2684,6 +2686,7 @@ void LCodeGen::DoLoadKeyedFastDoubleElement(
   Operand double_load_operand = BuildFastArrayOperand(
       instr->elements(),
       instr->key(),
+      instr->hydrogen()->key()->representation(),
       FAST_DOUBLE_ELEMENTS,
       FixedDoubleArray::kHeaderSize - kHeapObjectTag,
       instr->additional_index());
@@ -2694,11 +2697,15 @@ void LCodeGen::DoLoadKeyedFastDoubleElement(
 Operand LCodeGen::BuildFastArrayOperand(
     LOperand* elements_pointer,
     LOperand* key,
+    Representation key_representation,
     ElementsKind elements_kind,
     uint32_t offset,
     uint32_t additional_index) {
   Register elements_pointer_reg = ToRegister(elements_pointer);
   int shift_size = ElementsKindToShiftSize(elements_kind);
+  if (key_representation.IsTagged() && shift_size >= 1) {

[Michael Starzinger, 2012/07/19 21:02:23]

Can we also make this condition use !ExternalArrayOpRequiresTemp(...) and
instead ASSERT(shift_size >= kSmiTagSize)?

[danno, 2012/07/20 09:51:57]

Done.

[danno, 2012/07/20 10:40:27]

Actually, it turns out that ExternalArrayOpRequiresTemp test something
difference, and one is not replaceable by the other, so I'm leaving the code
as-is.

[Michael Starzinger, 2012/07/20 10:50:25]

I see, OK. Just use the kSmiTagSize constant.

+    shift_size -= 1;

[Michael Starzinger, 2012/07/19 21:02:23]

Can we use kSmiTagSize here?

[danno, 2012/07/20 09:51:57]

Done.

+  }
   if (key->IsConstantOperand()) {
     int constant_value = ToInteger32(LConstantOperand::cast(key));
     if (constant_value & 0xF0000000) {
@@ -2720,11 +2727,19 @@ Operand LCodeGen::BuildFastArrayOperand(
 void LCodeGen::DoLoadKeyedSpecializedArrayElement(
     LLoadKeyedSpecializedArrayElement* instr) {
   ElementsKind elements_kind = instr->elements_kind();
-  Operand operand(BuildFastArrayOperand(instr->external_pointer(),
-                                        instr->key(),
-                                        elements_kind,
-                                        0,
-                                        instr->additional_index()));
+  LOperand* key = instr->key();
+  if (!key->IsConstantOperand() &&
+      ExternalArrayOpRequiresTemp(instr->hydrogen()->key()->representation(),
+                                  elements_kind)) {
+    __ SmiUntag(ToRegister(key));
+  }
+  Operand operand(BuildFastArrayOperand(
+      instr->external_pointer(),
+      key,
+      instr->hydrogen()->key()->representation(),
+      elements_kind,
+      0,
+      instr->additional_index()));
   if (elements_kind == EXTERNAL_FLOAT_ELEMENTS) {
     XMMRegister result(ToDoubleRegister(instr->result()));
     __ movss(result, operand);
@@ -3677,11 +3692,19 @@ void LCodeGen::DoBoundsCheck(LBoundsCheck* instr) {
 void LCodeGen::DoStoreKeyedSpecializedArrayElement(
     LStoreKeyedSpecializedArrayElement* instr) {
   ElementsKind elements_kind = instr->elements_kind();
-  Operand operand(BuildFastArrayOperand(instr->external_pointer(),
-                                        instr->key(),
-                                        elements_kind,
-                                        0,
-                                        instr->additional_index()));
+  LOperand* key = instr->key();
+  if (!key->IsConstantOperand() &&
+      ExternalArrayOpRequiresTemp(instr->hydrogen()->key()->representation(),
+                                  elements_kind)) {
+    __ SmiUntag(ToRegister(key));
+  }
+  Operand operand(BuildFastArrayOperand(
+      instr->external_pointer(),
+      key,
+      instr->hydrogen()->key()->representation(),
+      elements_kind,
+      0,
+      instr->additional_index()));
   if (elements_kind == EXTERNAL_FLOAT_ELEMENTS) {
     __ cvtsd2ss(xmm0, ToDoubleRegister(instr->value()));
     __ movss(operand, xmm0);
@@ -3728,6 +3751,7 @@ void LCodeGen::DoStoreKeyedFastElement(LStoreKeyedFastElement* instr) {
   Operand operand = BuildFastArrayOperand(
       instr->object(),
       instr->key(),
+      instr->hydrogen()->key()->representation(),
       FAST_ELEMENTS,
       FixedArray::kHeaderSize - kHeapObjectTag,
       instr->additional_index());
@@ -3769,6 +3793,7 @@ void LCodeGen::DoStoreKeyedFastDoubleElement(
   Operand double_store_operand = BuildFastArrayOperand(
       instr->elements(),
       instr->key(),
+      instr->hydrogen()->key()->representation(),
       FAST_DOUBLE_ELEMENTS,
       FixedDoubleArray::kHeaderSize - kHeapObjectTag,
       instr->additional_index());