Add support to load/store byte fields.

src/arm/lithium-codegen-arm.cc

Index: src/arm/lithium-codegen-arm.cc
diff --git a/src/arm/lithium-codegen-arm.cc b/src/arm/lithium-codegen-arm.cc
index 97d763714b3646ca417d198fffafb771941f8bc0..13abf05bcc85f15ad5dd2572330495f97497d346 100644
--- a/src/arm/lithium-codegen-arm.cc
+++ b/src/arm/lithium-codegen-arm.cc
@@ -3098,7 +3098,12 @@ void LCodeGen::DoLoadNamedField(LLoadNamedField* instr) {
 
   if (access.IsExternalMemory()) {
     Register result = ToRegister(instr->result());
-    __ ldr(result, MemOperand(object, offset));
+    MemOperand operand = MemOperand(object, offset);
+    if (access.representation().IsByte()) {
+      __ ldrb(result, operand);
+    } else {
+      __ ldr(result, operand);
+    }
     return;
   }
 
@@ -3109,11 +3114,15 @@ void LCodeGen::DoLoadNamedField(LLoadNamedField* instr) {
   }
 
   Register result = ToRegister(instr->result());
-  if (access.IsInobject()) {
-    __ ldr(result, FieldMemOperand(object, offset));
-  } else {
+  if (!access.IsInobject()) {
     __ ldr(result, FieldMemOperand(object, JSObject::kPropertiesOffset));
-    __ ldr(result, FieldMemOperand(result, offset));
+    object = result;
+  }
+  MemOperand operand = FieldMemOperand(object, offset);
+  if (access.representation().IsByte()) {
+    __ ldrb(result, operand);
+  } else {
+    __ ldr(result, operand);
   }
 }
 
@@ -4219,7 +4228,12 @@ void LCodeGen::DoStoreNamedField(LStoreNamedField* instr) {
 
   if (access.IsExternalMemory()) {
     Register value = ToRegister(instr->value());
-    __ str(value, MemOperand(object, offset));
+    MemOperand operand = MemOperand(object, offset);
+    if (representation.IsByte()) {
+      __ strb(value, operand);
+    } else {
+      __ str(value, operand);
+    }
     return;
   }
 
@@ -4264,7 +4278,12 @@ void LCodeGen::DoStoreNamedField(LStoreNamedField* instr) {
       instr->hydrogen()->value()->IsHeapObject()
           ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
   if (access.IsInobject()) {
-    __ str(value, FieldMemOperand(object, offset));
+    MemOperand operand = FieldMemOperand(object, offset);
+    if (representation.IsByte()) {
+      __ strb(value, operand);
+    } else {
+      __ str(value, operand);
+    }
     if (instr->hydrogen()->NeedsWriteBarrier()) {
       // Update the write barrier for the object for in-object properties.
       __ RecordWriteField(object,
@@ -4278,7 +4297,12 @@ void LCodeGen::DoStoreNamedField(LStoreNamedField* instr) {
     }
   } else {
     __ ldr(scratch, FieldMemOperand(object, JSObject::kPropertiesOffset));
-    __ str(value, FieldMemOperand(scratch, offset));
+    MemOperand operand = FieldMemOperand(scratch, offset);
+    if (representation.IsByte()) {
+      __ strb(value, operand);
+    } else {
+      __ str(value, operand);
+    }
     if (instr->hydrogen()->NeedsWriteBarrier()) {
       // Update the write barrier for the properties array.
       // object is used as a scratch register.