Add support to load/store byte fields.

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 2fea50a175831232315430db45291f63b62a5cae..9423f5f38b9bbdbe604c26b0f17a40ff7272c256 100644
--- a/src/x64/lithium-codegen-x64.cc
+++ b/src/x64/lithium-codegen-x64.cc
@@ -2782,14 +2782,20 @@ void LCodeGen::DoLoadNamedField(LLoadNamedField* instr) {
   int offset = access.offset();
 
   if (access.IsExternalMemory()) {
-    ASSERT(!access.representation().IsInteger32());
     Register result = ToRegister(instr->result());
     if (instr->object()->IsConstantOperand()) {
       ASSERT(result.is(rax));
+      ASSERT(!access.representation().IsSpecialization());
       __ load_rax(ToExternalReference(LConstantOperand::cast(instr->object())));
     } else {
-      Register object = ToRegister(instr->object());
-      __ movq(result, MemOperand(object, offset));
+      MemOperand operand = MemOperand(ToRegister(instr->object()), offset);

[mvstanton, 2013/10/02 11:13:12]

How about a helper function that does the right move based on representation and
sign-extend like:

void LCodeGen::EmitAppropriateMove(Register result, 
    MemOperand operand,
    Representation representation,
    bool sign_extend);

All four of these locations could benefit from that.

[Benedikt Meurer, 2013/10/02 11:48:06]

Done.

+      if (access.representation().IsByte()) {
+        __ movzxbl(result, operand);
+      } else if (access.representation().IsInteger32()) {
+        __ movl(result, operand);
+      } else {
+        __ movq(result, operand);
+      }
     }
     return;
   }
@@ -2803,19 +2809,17 @@ void LCodeGen::DoLoadNamedField(LLoadNamedField* instr) {
   }
 
   Register result = ToRegister(instr->result());
-  if (access.IsInobject()) {
-    if (access.representation().IsInteger32()) {
-      __ movl(result, FieldOperand(object, offset));
-    } else {
-      __ movq(result, FieldOperand(object, offset));
-    }
-  } else {
+  if (!access.IsInobject()) {
     __ movq(result, FieldOperand(object, JSObject::kPropertiesOffset));
-    if (access.representation().IsInteger32()) {
-      __ movl(result, FieldOperand(result, offset));
-    } else {
-      __ movq(result, FieldOperand(result, offset));
-    }
+    object = result;
+  }
+  MemOperand operand = FieldOperand(object, offset);
+  if (access.representation().IsByte()) {
+    __ movzxbl(result, operand);
+  } else if (access.representation().IsInteger32()) {
+    __ movl(result, operand);
+  } else {
+    __ movq(result, operand);
   }
 }
 
@@ -3934,16 +3938,22 @@ void LCodeGen::DoStoreNamedField(LStoreNamedField* instr) {
   int offset = access.offset();
 
   if (access.IsExternalMemory()) {
-    ASSERT(!access.representation().IsInteger32());
     ASSERT(!instr->hydrogen()->NeedsWriteBarrier());
     Register value = ToRegister(instr->value());
     if (instr->object()->IsConstantOperand()) {
       ASSERT(value.is(rax));
+      ASSERT(!access.representation().IsSpecialization());
       LConstantOperand* object = LConstantOperand::cast(instr->object());
       __ store_rax(ToExternalReference(object));
     } else {
-      Register object = ToRegister(instr->object());
-      __ movq(MemOperand(object, offset), value);
+      MemOperand operand = MemOperand(ToRegister(instr->object()), offset);
+      if (representation.IsByte()) {
+        __ movb(operand, value);
+      } else if (representation.IsInteger32()) {
+        __ movl(operand, value);
+      } else {
+        __ movq(operand, value);
+      }
     }
     return;
   }
@@ -4009,26 +4019,31 @@ void LCodeGen::DoStoreNamedField(LStoreNamedField* instr) {
     __ movq(write_register, FieldOperand(object, JSObject::kPropertiesOffset));
   }
 
+  MemOperand operand = FieldOperand(write_register, offset);
   if (instr->value()->IsConstantOperand()) {
     LConstantOperand* operand_value = LConstantOperand::cast(instr->value());
     if (operand_value->IsRegister()) {
-      if (access.representation().IsInteger32()) {
-        __ movl(FieldOperand(write_register, offset),
-                ToRegister(operand_value));
+      Register value = ToRegister(operand_value);
+      if (representation.IsByte()) {
+        __ movb(operand, value);
+      } else if (representation.IsInteger32()) {
+        __ movl(operand, value);
       } else {
-        __ movq(FieldOperand(write_register, offset),
-                ToRegister(operand_value));
+        __ movq(operand, value);
       }
     } else {
       Handle<Object> handle_value = ToHandle(operand_value);
       ASSERT(!instr->hydrogen()->NeedsWriteBarrier());
-      __ Move(FieldOperand(write_register, offset), handle_value);
+      __ Move(operand, handle_value);
     }
   } else {
-    if (access.representation().IsInteger32()) {
-      __ movl(FieldOperand(write_register, offset), ToRegister(instr->value()));
+    Register value = ToRegister(instr->value());
+    if (representation.IsByte()) {
+      __ movb(operand, value);
+    } else if (representation.IsInteger32()) {
+      __ movl(operand, value);
     } else {
-      __ movq(FieldOperand(write_register, offset), ToRegister(instr->value()));
+      __ movq(operand, value);
     }
   }