A64: Fix int32 use in Lithium string functions

Assert register sizes in StringCharLoadGenerator, and fix char_code comparison
in DoStringCharFromCode.

BUG=
R=jochen@chromium.org

Review URL: https://codereview.chromium.org/172483002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19503 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/a64/code-stubs-a64.cc

@@ -3540,7 +3540,7 @@ void StringCharCodeAtGenerator::GenerateFast(MacroAssembler* masm) {
 
   StringCharLoadGenerator::Generate(masm,
                                     object_,
-                                    index_,
+                                    index_.W(),
                                     result_,
                                     &call_runtime_);
   __ SmiTag(result_);

src/a64/codegen-a64.cc

@@ -410,6 +410,7 @@ void StringCharLoadGenerator::Generate(MacroAssembler* masm,
                                        Register index,
                                        Register result,
                                        Label* call_runtime) {
+  ASSERT(string.Is64Bits() && index.Is32Bits() && result.Is64Bits());
   // Fetch the instance type of the receiver into result register.
   __ Ldr(result, FieldMemOperand(string, HeapObject::kMapOffset));
   __ Ldrb(result, FieldMemOperand(result, Map::kInstanceTypeOffset));
@@ -424,10 +425,10 @@ void StringCharLoadGenerator::Generate(MacroAssembler* masm,
 
   // Handle slices.
   Label indirect_string_loaded;
-  __ Ldrsw(result,
-           UntagSmiFieldMemOperand(string, SlicedString::kOffsetOffset));
+  __ Ldr(result.W(),
+         UntagSmiFieldMemOperand(string, SlicedString::kOffsetOffset));
   __ Ldr(string, FieldMemOperand(string, SlicedString::kParentOffset));
-  __ Add(index, index, result);
+  __ Add(index, index, result.W());
   __ B(&indirect_string_loaded);
 
   // Handle cons strings.
@@ -479,11 +480,11 @@ void StringCharLoadGenerator::Generate(MacroAssembler* masm,
   STATIC_ASSERT(kTwoByteStringTag == 0);
   __ TestAndBranchIfAnySet(result, kStringEncodingMask, &ascii);
   // Two-byte string.
-  __ Ldrh(result, MemOperand(string, index, LSL, 1));
+  __ Ldrh(result, MemOperand(string, index, SXTW, 1));
   __ B(&done);
   __ Bind(&ascii);
   // Ascii string.
-  __ Ldrb(result, MemOperand(string, index));
+  __ Ldrb(result, MemOperand(string, index, SXTW));
   __ Bind(&done);
 }
 

src/a64/codegen-a64.h

@@ -38,7 +38,8 @@ class StringCharLoadGenerator : public AllStatic {
  public:
   // Generates the code for handling different string types and loading the
   // indexed character into |result|.  We expect |index| as untagged input and
-  // |result| as untagged output.
+  // |result| as untagged output. Register index is asserted to be a 32-bit W
+  // register.
   static void Generate(MacroAssembler* masm,
                        Register string,
                        Register index,

src/a64/lithium-codegen-a64.cc

@@ -5161,7 +5161,7 @@ void LCodeGen::DoStringCharCodeAt(LStringCharCodeAt* instr) {
 
   StringCharLoadGenerator::Generate(masm(),
                                     ToRegister(instr->string()),
-                                    ToRegister(instr->index()),
+                                    ToRegister32(instr->index()),
                                     ToRegister(instr->result()),
                                     deferred->entry());
   __ Bind(deferred->exit());
@@ -5208,13 +5208,13 @@ void LCodeGen::DoStringCharFromCode(LStringCharFromCode* instr) {
       new(zone()) DeferredStringCharFromCode(this, instr);
 
   ASSERT(instr->hydrogen()->value()->representation().IsInteger32());
-  Register char_code = ToRegister(instr->char_code());
+  Register char_code = ToRegister32(instr->char_code());
   Register result = ToRegister(instr->result());
 
-  __ Cmp(char_code, Operand(String::kMaxOneByteCharCode));
+  __ Cmp(char_code, String::kMaxOneByteCharCode);
   __ B(hi, deferred->entry());
   __ LoadRoot(result, Heap::kSingleCharacterStringCacheRootIndex);
-  __ Add(result, result, Operand(char_code, LSL, kPointerSizeLog2));
+  __ Add(result, result, Operand(char_code, SXTW, kPointerSizeLog2));
   __ Ldr(result, FieldMemOperand(result, FixedArray::kHeaderSize));
   __ CompareRoot(result, Heap::kUndefinedValueRootIndex);
   __ B(eq, deferred->entry());