MIPS: Porting r10023 and r10054 to arm (pointer cache for external strings).

Port r10059 (c32f98a9)

Original commit message:

BUG=
TEST=

Review URL: http://codereview.chromium.org/8746015
Patch from Daniel Kalmar <kalmard@homejinni.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10107 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/mips/code-stubs-mips.cc

@@ -5288,77 +5288,14 @@ void StringCharCodeAtGenerator::GenerateFast(MacroAssembler* masm) {
   __ lw(t0, FieldMemOperand(object_, String::kLengthOffset));
   __ Branch(index_out_of_range_, ls, t0, Operand(index_));
 
-  // We need special handling for non-flat strings.
-  STATIC_ASSERT(kSeqStringTag == 0);
-  __ And(t0, result_, Operand(kStringRepresentationMask));
-  __ Branch(&flat_string, eq, t0, Operand(zero_reg));
-
-  // Handle non-flat strings.
-  __ And(result_, result_, Operand(kStringRepresentationMask));
-  STATIC_ASSERT(kConsStringTag < kExternalStringTag);
-  STATIC_ASSERT(kSlicedStringTag > kExternalStringTag);
-  __ Branch(&sliced_string, gt, result_, Operand(kExternalStringTag));
-  __ Branch(&call_runtime_, eq, result_, Operand(kExternalStringTag));
-
-  // ConsString.
-  // Check whether the right hand side is the empty string (i.e. if
-  // this is really a flat string in a cons string). If that is not
-  // the case we would rather go to the runtime system now to flatten
-  // the string.
-  Label assure_seq_string;
-  __ lw(result_, FieldMemOperand(object_, ConsString::kSecondOffset));
-  __ LoadRoot(t0, Heap::kEmptyStringRootIndex);
-  __ Branch(&call_runtime_, ne, result_, Operand(t0));
-
-  // Get the first of the two parts.
-  __ lw(object_, FieldMemOperand(object_, ConsString::kFirstOffset));
-  __ jmp(&assure_seq_string);
-
-  // SlicedString, unpack and add offset.
-  __ bind(&sliced_string);
-  __ lw(result_, FieldMemOperand(object_, SlicedString::kOffsetOffset));
-  __ Addu(index_, index_, result_);
-  __ lw(object_, FieldMemOperand(object_, SlicedString::kParentOffset));
-
-  // Assure that we are dealing with a sequential string. Go to runtime if not.
-  __ bind(&assure_seq_string);
-  __ lw(result_, FieldMemOperand(object_, HeapObject::kMapOffset));
-  __ lbu(result_, FieldMemOperand(result_, Map::kInstanceTypeOffset));
-  // Check that parent is not an external string. Go to runtime otherwise.
-  // Note that if the original string is a cons or slice with an external
-  // string as underlying string, we pass that unpacked underlying string with
-  // the adjusted index to the runtime function.
-  STATIC_ASSERT(kSeqStringTag == 0);
-
-  __ And(t0, result_, Operand(kStringRepresentationMask));
-  __ Branch(&call_runtime_, ne, t0, Operand(zero_reg));
-
-  // Check for 1-byte or 2-byte string.
-  __ bind(&flat_string);
-  STATIC_ASSERT((kStringEncodingMask & kAsciiStringTag) != 0);
-  STATIC_ASSERT((kStringEncodingMask & kTwoByteStringTag) == 0);
-  __ And(t0, result_, Operand(kStringEncodingMask));
-  __ Branch(&ascii_string, ne, t0, Operand(zero_reg));
-
-  // 2-byte string.
-  // Load the 2-byte character code into the result register. We can
-  // add without shifting since the smi tag size is the log2 of the
-  // number of bytes in a two-byte character.
-  STATIC_ASSERT(kSmiTag == 0 && kSmiTagSize == 1 && kSmiShiftSize == 0);
-  __ Addu(index_, object_, Operand(index_));
-  __ lhu(result_, FieldMemOperand(index_, SeqTwoByteString::kHeaderSize));
-  __ Branch(&got_char_code);
-
-  // ASCII string.
-  // Load the byte into the result register.
-  __ bind(&ascii_string);
-
-  __ srl(t0, index_, kSmiTagSize);
-  __ Addu(index_, object_, t0);
+  __ sra(index_, index_, kSmiTagSize);
 
-  __ lbu(result_, FieldMemOperand(index_, SeqAsciiString::kHeaderSize));
+  StringCharLoadGenerator::Generate(masm,
+                                    object_,
+                                    index_,
+                                    result_,
+                                    &call_runtime_);
 
-  __ bind(&got_char_code);
   __ sll(result_, result_, kSmiTagSize);
   __ bind(&exit_);
 }
@@ -5407,6 +5344,7 @@ void StringCharCodeAtGenerator::GenerateSlow(
   // is too complex (e.g., when the string needs to be flattened).
   __ bind(&call_runtime_);
   call_helper.BeforeCall(masm);
+  __ sll(index_, index_, kSmiTagSize);
   __ Push(object_, index_);
   __ CallRuntime(Runtime::kStringCharCodeAt, 2);
 

src/mips/codegen-mips.cc

@@ -310,6 +310,98 @@ void ElementsTransitionGenerator::GenerateDoubleToObject(
   __ pop(ra);
 }
 
+
+void StringCharLoadGenerator::Generate(MacroAssembler* masm,
+                                       Register string,
+                                       Register index,
+                                       Register result,
+                                       Label* call_runtime) {
+  // Fetch the instance type of the receiver into result register.
+  __ lw(result, FieldMemOperand(string, HeapObject::kMapOffset));
+  __ lbu(result, FieldMemOperand(result, Map::kInstanceTypeOffset));
+
+  // We need special handling for indirect strings.
+  Label check_sequential;
+  __ And(at, result, Operand(kIsIndirectStringMask));
+  __ Branch(&check_sequential, eq, at, Operand(zero_reg));
+
+  // Dispatch on the indirect string shape: slice or cons.
+  Label cons_string;
+  __ And(at, result, Operand(kSlicedNotConsMask));
+  __ Branch(&cons_string, eq, at, Operand(zero_reg));
+
+  // Handle slices.
+  Label indirect_string_loaded;
+  __ lw(result, FieldMemOperand(string, SlicedString::kOffsetOffset));
+  __ sra(at, result, kSmiTagSize);
+  __ Addu(index, index, at);
+  __ lw(string, FieldMemOperand(string, SlicedString::kParentOffset));
+  __ jmp(&indirect_string_loaded);
+
+  // Handle cons strings.
+  // Check whether the right hand side is the empty string (i.e. if
+  // this is really a flat string in a cons string). If that is not
+  // the case we would rather go to the runtime system now to flatten
+  // the string.
+  __ bind(&cons_string);
+  __ lw(result, FieldMemOperand(string, ConsString::kSecondOffset));
+  __ LoadRoot(at, Heap::kEmptyStringRootIndex);
+  __ Branch(call_runtime, ne, result, Operand(at));
+  // Get the first of the two strings and load its instance type.
+  __ lw(string, FieldMemOperand(string, ConsString::kFirstOffset));
+
+  __ bind(&indirect_string_loaded);
+  __ lw(result, FieldMemOperand(string, HeapObject::kMapOffset));
+  __ lbu(result, FieldMemOperand(result, Map::kInstanceTypeOffset));
+
+  // Distinguish sequential and external strings. Only these two string
+  // representations can reach here (slices and flat cons strings have been
+  // reduced to the underlying sequential or external string).
+  Label external_string, check_encoding;
+  __ bind(&check_sequential);
+  STATIC_ASSERT(kSeqStringTag == 0);
+  __ And(at, result, Operand(kStringRepresentationMask));
+  __ Branch(&external_string, ne, at, Operand(zero_reg));
+
+  // Prepare sequential strings
+  STATIC_ASSERT(SeqTwoByteString::kHeaderSize == SeqAsciiString::kHeaderSize);
+  __ Addu(string,
+          string,
+          SeqTwoByteString::kHeaderSize - kHeapObjectTag);
+  __ jmp(&check_encoding);
+
+  // Handle external strings.
+  __ bind(&external_string);
+  if (FLAG_debug_code) {
+    // Assert that we do not have a cons or slice (indirect strings) here.
+    // Sequential strings have already been ruled out.
+    __ And(at, result, Operand(kIsIndirectStringMask));
+    __ Assert(eq, "external string expected, but not found",
+        at, Operand(zero_reg));
+  }
+  // Rule out short external strings.
+  STATIC_CHECK(kShortExternalStringTag != 0);
+  __ And(at, result, Operand(kShortExternalStringMask));
+  __ Branch(call_runtime, ne, at, Operand(zero_reg));
+  __ lw(string, FieldMemOperand(string, ExternalString::kResourceDataOffset));
+
+  Label ascii, done;
+  __ bind(&check_encoding);
+  STATIC_ASSERT(kTwoByteStringTag == 0);
+  __ And(at, result, Operand(kStringEncodingMask));
+  __ Branch(&ascii, ne, at, Operand(zero_reg));
+  // Two-byte string.
+  __ sll(at, index, 1);
+  __ Addu(at, string, at);
+  __ lhu(result, MemOperand(at));
+  __ jmp(&done);
+  __ bind(&ascii);
+  // Ascii string.
+  __ Addu(at, string, index);
+  __ lbu(result, MemOperand(at));
+  __ bind(&done);
+}
+
 #undef __
 
 } }  // namespace v8::internal

src/mips/codegen-mips.h

@@ -75,6 +75,21 @@ class CodeGenerator: public AstVisitor {
 };
 
 
+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.
+  static void Generate(MacroAssembler* masm,
+                       Register string,
+                       Register index,
+                       Register result,
+                       Label* call_runtime);
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(StringCharLoadGenerator);
+};
+
 } }  // namespace v8::internal
 
 #endif  // V8_MIPS_CODEGEN_MIPS_H_

src/mips/lithium-codegen-mips.cc

@@ -3520,89 +3520,13 @@ void LCodeGen::DoStringCharCodeAt(LStringCharCodeAt* instr) {
     LStringCharCodeAt* instr_;
   };
 
-  Register temp = scratch1();
-  Register string = ToRegister(instr->string());
-  Register index = ToRegister(instr->index());
-  Register result = ToRegister(instr->result());
   DeferredStringCharCodeAt* deferred =
       new DeferredStringCharCodeAt(this, instr);
-
-  // Fetch the instance type of the receiver into result register.
-  __ lw(result, FieldMemOperand(string, HeapObject::kMapOffset));
-  __ lbu(result, FieldMemOperand(result, Map::kInstanceTypeOffset));
-
-  // We need special handling for indirect strings.
-  Label check_sequential;
-  __ And(temp, result, kIsIndirectStringMask);
-  __ Branch(&check_sequential, eq, temp, Operand(zero_reg));
-
-  // Dispatch on the indirect string shape: slice or cons.
-  Label cons_string;
-  __ And(temp, result, kSlicedNotConsMask);
-  __ Branch(&cons_string, eq, temp, Operand(zero_reg));
-
-  // Handle slices.
-  Label indirect_string_loaded;
-  __ lw(result, FieldMemOperand(string, SlicedString::kOffsetOffset));
-  __ sra(temp, result, kSmiTagSize);
-  __ addu(index, index, temp);
-  __ lw(string, FieldMemOperand(string, SlicedString::kParentOffset));
-  __ jmp(&indirect_string_loaded);
-
-  // Handle conses.
-  // Check whether the right hand side is the empty string (i.e. if
-  // this is really a flat string in a cons string). If that is not
-  // the case we would rather go to the runtime system now to flatten
-  // the string.
-  __ bind(&cons_string);
-  __ lw(result, FieldMemOperand(string, ConsString::kSecondOffset));
-  __ LoadRoot(temp, Heap::kEmptyStringRootIndex);
-  __ Branch(deferred->entry(), ne, result, Operand(temp));
-  // Get the first of the two strings and load its instance type.
-  __ lw(string, FieldMemOperand(string, ConsString::kFirstOffset));
-
-  __ bind(&indirect_string_loaded);
-  __ lw(result, FieldMemOperand(string, HeapObject::kMapOffset));
-  __ lbu(result, FieldMemOperand(result, Map::kInstanceTypeOffset));
-
-  // Check whether the string is sequential. The only non-sequential
-  // shapes we support have just been unwrapped above.
-  // Note that if the original string is a cons or slice with an external
-  // string as underlying string, we pass that unpacked underlying string with
-  // the adjusted index to the runtime function.
-  __ bind(&check_sequential);
-  STATIC_ASSERT(kSeqStringTag == 0);
-  __ And(temp, result, Operand(kStringRepresentationMask));
-  __ Branch(deferred->entry(), ne, temp, Operand(zero_reg));
-
-  // Dispatch on the encoding: ASCII or two-byte.
-  Label ascii_string;
-  STATIC_ASSERT((kStringEncodingMask & kAsciiStringTag) != 0);
-  STATIC_ASSERT((kStringEncodingMask & kTwoByteStringTag) == 0);
-  __ And(temp, result, Operand(kStringEncodingMask));
-  __ Branch(&ascii_string, ne, temp, Operand(zero_reg));
-
-  // Two-byte string.
-  // Load the two-byte character code into the result register.
-  Label done;
-  __ Addu(result,
-          string,
-          Operand(SeqTwoByteString::kHeaderSize - kHeapObjectTag));
-  __ sll(temp, index, 1);
-  __ Addu(result, result, temp);
-  __ lhu(result, MemOperand(result, 0));
-  __ Branch(&done);
-
-  // ASCII string.
-  // Load the byte into the result register.
-  __ bind(&ascii_string);
-  __ Addu(result,
-          string,
-          Operand(SeqAsciiString::kHeaderSize - kHeapObjectTag));
-  __ Addu(result, result, index);
-  __ lbu(result, MemOperand(result, 0));
-
-  __ bind(&done);
+  StringCharLoadGenerator::Generate(masm(),
+                                    ToRegister(instr->string()),
+                                    ToRegister(instr->index()),
+                                    ToRegister(instr->result()),
+                                    deferred->entry());
   __ bind(deferred->exit());
 }