Add support to load/store byte fields.

src/ia32/lithium-codegen-ia32.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 3207 matching lines @@
   __ bind(&skip_assignment);
 }
 
 
 void LCodeGen::DoLoadNamedField(LLoadNamedField* instr) {
   HObjectAccess access = instr->hydrogen()->access();
   int offset = access.offset();
 
   if (access.IsExternalMemory()) {
     Register result = ToRegister(instr->result());
-    if (instr->object()->IsConstantOperand()) {
-      ExternalReference external_reference = ToExternalReference(
-          LConstantOperand::cast(instr->object()));
-      __ mov(result, MemOperand::StaticVariable(external_reference));
+    MemOperand operand = instr->object()->IsConstantOperand()
+        ? MemOperand::StaticVariable(ToExternalReference(
+                LConstantOperand::cast(instr->object())))
+        : MemOperand(ToRegister(instr->object()), offset);
+    if (access.representation().IsByte()) {
+      ASSERT(instr->hydrogen()->representation().IsInteger32());
+      __ movzx_b(result, operand);
     } else {
-      __ mov(result, MemOperand(ToRegister(instr->object()), offset));
+      __ mov(result, operand);
     }
     return;
   }
 
   Register object = ToRegister(instr->object());
   if (FLAG_track_double_fields &&
       instr->hydrogen()->representation().IsDouble()) {
     if (CpuFeatures::IsSupported(SSE2)) {
       CpuFeatureScope scope(masm(), SSE2);
       XMMRegister result = ToDoubleRegister(instr->result());
       __ movdbl(result, FieldOperand(object, offset));
     } else {
       X87Mov(ToX87Register(instr->result()), FieldOperand(object, offset));
     }
     return;
   }
 
   Register result = ToRegister(instr->result());
-  if (access.IsInobject()) {
+  if (!access.IsInobject()) {
+    __ mov(result, FieldOperand(object, JSObject::kPropertiesOffset));
+    object = result;
+  }
+  if (access.representation().IsByte()) {
+    ASSERT(instr->hydrogen()->representation().IsInteger32());
+    __ movzx_b(result, FieldOperand(object, offset));
+  } else {
     __ mov(result, FieldOperand(object, offset));
-  } else {
-    __ mov(result, FieldOperand(object, JSObject::kPropertiesOffset));
-    __ mov(result, FieldOperand(result, offset));
   }
 }
 
 
 void LCodeGen::EmitPushTaggedOperand(LOperand* operand) {
   ASSERT(!operand->IsDoubleRegister());
   if (operand->IsConstantOperand()) {
     Handle<Object> object = ToHandle(LConstantOperand::cast(operand));
     AllowDeferredHandleDereference smi_check;
     if (object->IsSmi()) {
@@ skipping 1155 matching lines @@
   int offset = access.offset();
 
   if (access.IsExternalMemory()) {
     ASSERT(!instr->hydrogen()->NeedsWriteBarrier());
     MemOperand operand = instr->object()->IsConstantOperand()
         ? MemOperand::StaticVariable(
             ToExternalReference(LConstantOperand::cast(instr->object())))
         : MemOperand(ToRegister(instr->object()), offset);
     if (instr->value()->IsConstantOperand()) {
       LConstantOperand* operand_value = LConstantOperand::cast(instr->value());
-      __ mov(operand, Immediate(ToInteger32(operand_value)));
+      if (representation.IsByte()) {
+        __ mov_b(operand, ToInteger32(operand_value));

[Jakob Kummerow, 2013/10/02 16:25:42]

Here you're passing an int32_t to a function that expects an int8_t. I'm
surprised this even compiles on Windows.

[Benedikt Meurer, 2013/10/04 07:14:53]

It simply truncates to int8_t according to implicit type conversion rules. Just
what we want here.

+      } else {
+        __ mov(operand, Immediate(ToInteger32(operand_value)));
+      }
     } else {
       Register value = ToRegister(instr->value());
-      __ mov(operand, value);
+      if (representation.IsByte()) {
+        __ mov_b(operand, value);

[Jakob Kummerow, 2013/10/02 16:25:42]

This will fail the CHECK in mov_b when the register allocator happens to pick,
say, edi for |value|. If you had added a test case, you would have noticed ;-)

Same thing twice more below.

[Benedikt Meurer, 2013/10/04 07:14:53]

Good catch, thanks.

+      } else {
+        __ mov(operand, value);
+      }
     }
     return;
   }
 
   Register object = ToRegister(instr->object());
   Handle<Map> transition = instr->transition();
 
   if (FLAG_track_fields && representation.IsSmi()) {
     if (instr->value()->IsConstantOperand()) {
       LConstantOperand* operand_value = LConstantOperand::cast(instr->value());
@@ skipping 52 matching lines @@
   SmiCheck check_needed =
       instr->hydrogen()->value()->IsHeapObject()
           ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
 
   Register write_register = object;
   if (!access.IsInobject()) {
     write_register = ToRegister(instr->temp());
     __ mov(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()) {
-      __ mov(FieldOperand(write_register, offset), ToRegister(operand_value));
+      Register value = ToRegister(operand_value);
+      if (representation.IsByte()) {
+        __ mov_b(operand, value);
+      } else {
+        __ mov(operand, value);
+      }
     } else {
       Handle<Object> handle_value = ToHandle(operand_value);
       ASSERT(!instr->hydrogen()->NeedsWriteBarrier());
-      __ mov(FieldOperand(write_register, offset), handle_value);
+      __ mov(operand, handle_value);
     }
   } else {
-    __ mov(FieldOperand(write_register, offset), ToRegister(instr->value()));
+    Register value = ToRegister(instr->value());
+    if (representation.IsByte()) {
+      __ mov_b(operand, value);
+    } else {
+      __ mov(operand, value);
+    }
   }
 
   if (instr->hydrogen()->NeedsWriteBarrier()) {
     Register value = ToRegister(instr->value());
     Register temp = access.IsInobject() ? ToRegister(instr->temp()) : object;
     // Update the write barrier for the object for in-object properties.
     __ RecordWriteField(write_register,
                         offset,
                         value,
                         temp,
@@ skipping 1825 matching lines @@
                               FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32