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// Copyright 2006-2008 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
// with the distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#ifndef V8_CODE_STUBS_H_
#define V8_CODE_STUBS_H_
#include "globals.h"
namespace v8 {
namespace internal {
// List of code stubs used on all platforms. The order in this list is important
// as only the stubs up to and including RecordWrite allows nested stub calls.
#define CODE_STUB_LIST_ALL_PLATFORMS(V) \
V(CallFunction) \
V(GenericBinaryOp) \
V(TypeRecordingBinaryOp) \
V(StringAdd) \
V(StringCharAt) \
V(SubString) \
V(StringCompare) \
V(SmiOp) \
V(Compare) \
V(CompareIC) \
V(MathPow) \
V(TranscendentalCache) \
V(RecordWrite) \
V(ConvertToDouble) \
V(WriteInt32ToHeapNumber) \
V(IntegerMod) \
V(StackCheck) \
V(FastNewClosure) \
V(FastNewContext) \
V(FastCloneShallowArray) \
V(GenericUnaryOp) \
V(RevertToNumber) \
V(ToBoolean) \
V(Instanceof) \
V(CounterOp) \
V(ArgumentsAccess) \
V(RegExpExec) \
V(RegExpConstructResult) \
V(NumberToString) \
V(CEntry) \
V(JSEntry) \
V(DebuggerStatement)
// List of code stubs only used on ARM platforms.
#ifdef V8_TARGET_ARCH_ARM
#define CODE_STUB_LIST_ARM(V) \
V(GetProperty) \
V(SetProperty) \
V(InvokeBuiltin) \
V(RegExpCEntry)
#else
#define CODE_STUB_LIST_ARM(V)
#endif
// Combined list of code stubs.
#define CODE_STUB_LIST(V) \
CODE_STUB_LIST_ALL_PLATFORMS(V) \
CODE_STUB_LIST_ARM(V)
// Types of uncatchable exceptions.
enum UncatchableExceptionType { OUT_OF_MEMORY, TERMINATION };
// Mode to overwrite BinaryExpression values.
enum OverwriteMode { NO_OVERWRITE, OVERWRITE_LEFT, OVERWRITE_RIGHT };
enum UnaryOverwriteMode { UNARY_OVERWRITE, UNARY_NO_OVERWRITE };
// Stub is base classes of all stubs.
class CodeStub BASE_EMBEDDED {
public:
enum Major {
#define DEF_ENUM(name) name,
CODE_STUB_LIST(DEF_ENUM)
#undef DEF_ENUM
NoCache, // marker for stubs that do custom caching
NUMBER_OF_IDS
};
// Retrieve the code for the stub. Generate the code if needed.
Handle<Code> GetCode();
// Retrieve the code for the stub if already generated. Do not
// generate the code if not already generated and instead return a
// retry after GC Failure object.
MUST_USE_RESULT MaybeObject* TryGetCode();
static Major MajorKeyFromKey(uint32_t key) {
return static_cast<Major>(MajorKeyBits::decode(key));
}
static int MinorKeyFromKey(uint32_t key) {
return MinorKeyBits::decode(key);
}
// Gets the major key from a code object that is a code stub or binary op IC.
static Major GetMajorKey(Code* code_stub) {
return static_cast<Major>(code_stub->major_key());
}
static const char* MajorName(Major major_key, bool allow_unknown_keys);
virtual ~CodeStub() {}
protected:
static const int kMajorBits = 6;
static const int kMinorBits = kBitsPerInt - kSmiTagSize - kMajorBits;
private:
// Lookup the code in the (possibly custom) cache.
bool FindCodeInCache(Code** code_out);
// Nonvirtual wrapper around the stub-specific Generate function. Call
// this function to set up the macro assembler and generate the code.
void GenerateCode(MacroAssembler* masm);
// Generates the assembler code for the stub.
virtual void Generate(MacroAssembler* masm) = 0;
// Perform bookkeeping required after code generation when stub code is
// initially generated.
void RecordCodeGeneration(Code* code, MacroAssembler* masm);
// Finish the code object after it has been generated.
virtual void FinishCode(Code* code) { }
// Returns information for computing the number key.
virtual Major MajorKey() = 0;
virtual int MinorKey() = 0;
// The CallFunctionStub needs to override this so it can encode whether a
// lazily generated function should be fully optimized or not.
virtual InLoopFlag InLoop() { return NOT_IN_LOOP; }
// GenericBinaryOpStub needs to override this.
virtual int GetCodeKind();
// GenericBinaryOpStub needs to override this.
virtual InlineCacheState GetICState() {
return UNINITIALIZED;
}
// Returns a name for logging/debugging purposes.
virtual const char* GetName() { return MajorName(MajorKey(), false); }
#ifdef DEBUG
virtual void Print() { PrintF("%s\n", GetName()); }
#endif
// Computes the key based on major and minor.
uint32_t GetKey() {
ASSERT(static_cast<int>(MajorKey()) < NUMBER_OF_IDS);
return MinorKeyBits::encode(MinorKey()) |
MajorKeyBits::encode(MajorKey());
}
bool AllowsStubCalls() { return MajorKey() <= RecordWrite; }
class MajorKeyBits: public BitField<uint32_t, 0, kMajorBits> {};
class MinorKeyBits: public BitField<uint32_t, kMajorBits, kMinorBits> {};
friend class BreakPointIterator;
};
// Helper interface to prepare to/restore after making runtime calls.
class RuntimeCallHelper {
public:
virtual ~RuntimeCallHelper() {}
virtual void BeforeCall(MacroAssembler* masm) const = 0;
virtual void AfterCall(MacroAssembler* masm) const = 0;
protected:
RuntimeCallHelper() {}
private:
DISALLOW_COPY_AND_ASSIGN(RuntimeCallHelper);
};
} } // namespace v8::internal
#if V8_TARGET_ARCH_IA32
#include "ia32/code-stubs-ia32.h"
#elif V8_TARGET_ARCH_X64
#include "x64/code-stubs-x64.h"
#elif V8_TARGET_ARCH_ARM
#include "arm/code-stubs-arm.h"
#elif V8_TARGET_ARCH_MIPS
#include "mips/code-stubs-mips.h"
#else
#error Unsupported target architecture.
#endif
namespace v8 {
namespace internal {
// RuntimeCallHelper implementation used in stubs: enters/leaves a
// newly created internal frame before/after the runtime call.
class StubRuntimeCallHelper : public RuntimeCallHelper {
public:
StubRuntimeCallHelper() {}
virtual void BeforeCall(MacroAssembler* masm) const;
virtual void AfterCall(MacroAssembler* masm) const;
};
// Trivial RuntimeCallHelper implementation.
class NopRuntimeCallHelper : public RuntimeCallHelper {
public:
NopRuntimeCallHelper() {}
virtual void BeforeCall(MacroAssembler* masm) const {}
virtual void AfterCall(MacroAssembler* masm) const {}
};
class StackCheckStub : public CodeStub {
public:
StackCheckStub() { }
void Generate(MacroAssembler* masm);
private:
const char* GetName() { return "StackCheckStub"; }
Major MajorKey() { return StackCheck; }
int MinorKey() { return 0; }
};
class FastNewClosureStub : public CodeStub {
public:
void Generate(MacroAssembler* masm);
private:
const char* GetName() { return "FastNewClosureStub"; }
Major MajorKey() { return FastNewClosure; }
int MinorKey() { return 0; }
};
class FastNewContextStub : public CodeStub {
public:
static const int kMaximumSlots = 64;
explicit FastNewContextStub(int slots) : slots_(slots) {
ASSERT(slots_ > 0 && slots <= kMaximumSlots);
}
void Generate(MacroAssembler* masm);
private:
int slots_;
const char* GetName() { return "FastNewContextStub"; }
Major MajorKey() { return FastNewContext; }
int MinorKey() { return slots_; }
};
class FastCloneShallowArrayStub : public CodeStub {
public:
// Maximum length of copied elements array.
static const int kMaximumClonedLength = 8;
enum Mode {
CLONE_ELEMENTS,
COPY_ON_WRITE_ELEMENTS
};
FastCloneShallowArrayStub(Mode mode, int length)
: mode_(mode),
length_((mode == COPY_ON_WRITE_ELEMENTS) ? 0 : length) {
ASSERT(length_ >= 0);
ASSERT(length_ <= kMaximumClonedLength);
}
void Generate(MacroAssembler* masm);
private:
Mode mode_;
int length_;
const char* GetName() { return "FastCloneShallowArrayStub"; }
Major MajorKey() { return FastCloneShallowArray; }
int MinorKey() {
ASSERT(mode_ == 0 || mode_ == 1);
return (length_ << 1) | mode_;
}
};
class InstanceofStub: public CodeStub {
public:
enum Flags {
kNoFlags = 0,
kArgsInRegisters = 1 << 0
};
explicit InstanceofStub(Flags flags) : flags_(flags) { }
void Generate(MacroAssembler* masm);
private:
Major MajorKey() { return Instanceof; }
int MinorKey() { return args_in_registers() ? 1 : 0; }
bool args_in_registers() {
return (flags_ & kArgsInRegisters) != 0;
}
Flags flags_;
};
enum NegativeZeroHandling {
kStrictNegativeZero,
kIgnoreNegativeZero
};
enum UnaryOpFlags {
NO_UNARY_FLAGS = 0,
NO_UNARY_SMI_CODE_IN_STUB = 1 << 0
};
class GenericUnaryOpStub : public CodeStub {
public:
GenericUnaryOpStub(Token::Value op,
UnaryOverwriteMode overwrite,
UnaryOpFlags flags,
NegativeZeroHandling negative_zero = kStrictNegativeZero)
: op_(op),
overwrite_(overwrite),
include_smi_code_((flags & NO_UNARY_SMI_CODE_IN_STUB) == 0),
negative_zero_(negative_zero) { }
private:
Token::Value op_;
UnaryOverwriteMode overwrite_;
bool include_smi_code_;
NegativeZeroHandling negative_zero_;
class OverwriteField: public BitField<UnaryOverwriteMode, 0, 1> {};
class IncludeSmiCodeField: public BitField<bool, 1, 1> {};
class NegativeZeroField: public BitField<NegativeZeroHandling, 2, 1> {};
class OpField: public BitField<Token::Value, 3, kMinorBits - 3> {};
Major MajorKey() { return GenericUnaryOp; }
int MinorKey() {
return OpField::encode(op_) |
OverwriteField::encode(overwrite_) |
IncludeSmiCodeField::encode(include_smi_code_) |
NegativeZeroField::encode(negative_zero_);
}
void Generate(MacroAssembler* masm);
const char* GetName();
};
class MathPowStub: public CodeStub {
public:
MathPowStub() {}
virtual void Generate(MacroAssembler* masm);
private:
virtual CodeStub::Major MajorKey() { return MathPow; }
virtual int MinorKey() { return 0; }
const char* GetName() { return "MathPowStub"; }
};
class StringCharAtStub: public CodeStub {
public:
StringCharAtStub() {}
private:
Major MajorKey() { return StringCharAt; }
int MinorKey() { return 0; }
void Generate(MacroAssembler* masm);
};
class ICCompareStub: public CodeStub {
public:
ICCompareStub(Token::Value op, CompareIC::State state)
: op_(op), state_(state) {
ASSERT(Token::IsCompareOp(op));
}
virtual void Generate(MacroAssembler* masm);
private:
class OpField: public BitField<int, 0, 3> { };
class StateField: public BitField<int, 3, 5> { };
virtual void FinishCode(Code* code) { code->set_compare_state(state_); }
virtual CodeStub::Major MajorKey() { return CompareIC; }
virtual int MinorKey();
virtual int GetCodeKind() { return Code::COMPARE_IC; }
void GenerateSmis(MacroAssembler* masm);
void GenerateHeapNumbers(MacroAssembler* masm);
void GenerateObjects(MacroAssembler* masm);
void GenerateMiss(MacroAssembler* masm);
bool strict() const { return op_ == Token::EQ_STRICT; }
Condition GetCondition() const { return CompareIC::ComputeCondition(op_); }
Token::Value op_;
CompareIC::State state_;
};
// Flags that control the compare stub code generation.
enum CompareFlags {
NO_COMPARE_FLAGS = 0,
NO_SMI_COMPARE_IN_STUB = 1 << 0,
NO_NUMBER_COMPARE_IN_STUB = 1 << 1,
CANT_BOTH_BE_NAN = 1 << 2
};
enum NaNInformation {
kBothCouldBeNaN,
kCantBothBeNaN
};
class CompareStub: public CodeStub {
public:
CompareStub(Condition cc,
bool strict,
CompareFlags flags,
Register lhs,
Register rhs) :
cc_(cc),
strict_(strict),
never_nan_nan_((flags & CANT_BOTH_BE_NAN) != 0),
include_number_compare_((flags & NO_NUMBER_COMPARE_IN_STUB) == 0),
include_smi_compare_((flags & NO_SMI_COMPARE_IN_STUB) == 0),
lhs_(lhs),
rhs_(rhs),
name_(NULL) { }
CompareStub(Condition cc,
bool strict,
CompareFlags flags) :
cc_(cc),
strict_(strict),
never_nan_nan_((flags & CANT_BOTH_BE_NAN) != 0),
include_number_compare_((flags & NO_NUMBER_COMPARE_IN_STUB) == 0),
include_smi_compare_((flags & NO_SMI_COMPARE_IN_STUB) == 0),
lhs_(no_reg),
rhs_(no_reg),
name_(NULL) { }
void Generate(MacroAssembler* masm);
private:
Condition cc_;
bool strict_;
// Only used for 'equal' comparisons. Tells the stub that we already know
// that at least one side of the comparison is not NaN. This allows the
// stub to use object identity in the positive case. We ignore it when
// generating the minor key for other comparisons to avoid creating more
// stubs.
bool never_nan_nan_;
// Do generate the number comparison code in the stub. Stubs without number
// comparison code is used when the number comparison has been inlined, and
// the stub will be called if one of the operands is not a number.
bool include_number_compare_;
// Generate the comparison code for two smi operands in the stub.
bool include_smi_compare_;
// Register holding the left hand side of the comparison if the stub gives
// a choice, no_reg otherwise.
Register lhs_;
// Register holding the right hand side of the comparison if the stub gives
// a choice, no_reg otherwise.
Register rhs_;
// Encoding of the minor key in 16 bits.
class StrictField: public BitField<bool, 0, 1> {};
class NeverNanNanField: public BitField<bool, 1, 1> {};
class IncludeNumberCompareField: public BitField<bool, 2, 1> {};
class IncludeSmiCompareField: public BitField<bool, 3, 1> {};
class RegisterField: public BitField<bool, 4, 1> {};
class ConditionField: public BitField<int, 5, 11> {};
Major MajorKey() { return Compare; }
int MinorKey();
virtual int GetCodeKind() { return Code::COMPARE_IC; }
virtual void FinishCode(Code* code) {
code->set_compare_state(CompareIC::GENERIC);
}
// Branch to the label if the given object isn't a symbol.
void BranchIfNonSymbol(MacroAssembler* masm,
Label* label,
Register object,
Register scratch);
// Unfortunately you have to run without snapshots to see most of these
// names in the profile since most compare stubs end up in the snapshot.
char* name_;
const char* GetName();
#ifdef DEBUG
void Print() {
PrintF("CompareStub (minor %d) (cc %d), (strict %s), "
"(never_nan_nan %s), (smi_compare %s) (number_compare %s) ",
MinorKey(),
static_cast<int>(cc_),
strict_ ? "true" : "false",
never_nan_nan_ ? "true" : "false",
include_smi_compare_ ? "inluded" : "not included",
include_number_compare_ ? "included" : "not included");
if (!lhs_.is(no_reg) && !rhs_.is(no_reg)) {
PrintF("(lhs r%d), (rhs r%d)\n", lhs_.code(), rhs_.code());
} else {
PrintF("\n");
}
}
#endif
};
class CEntryStub : public CodeStub {
public:
explicit CEntryStub(int result_size)
: result_size_(result_size), save_doubles_(false) { }
void Generate(MacroAssembler* masm);
void SaveDoubles() { save_doubles_ = true; }
private:
void GenerateCore(MacroAssembler* masm,
Label* throw_normal_exception,
Label* throw_termination_exception,
Label* throw_out_of_memory_exception,
bool do_gc,
bool always_allocate_scope,
int alignment_skew = 0);
void GenerateThrowTOS(MacroAssembler* masm);
void GenerateThrowUncatchable(MacroAssembler* masm,
UncatchableExceptionType type);
// Number of pointers/values returned.
const int result_size_;
bool save_doubles_;
Major MajorKey() { return CEntry; }
int MinorKey();
const char* GetName() { return "CEntryStub"; }
};
class JSEntryStub : public CodeStub {
public:
JSEntryStub() { }
void Generate(MacroAssembler* masm) { GenerateBody(masm, false); }
protected:
void GenerateBody(MacroAssembler* masm, bool is_construct);
private:
Major MajorKey() { return JSEntry; }
int MinorKey() { return 0; }
const char* GetName() { return "JSEntryStub"; }
};
class JSConstructEntryStub : public JSEntryStub {
public:
JSConstructEntryStub() { }
void Generate(MacroAssembler* masm) { GenerateBody(masm, true); }
private:
int MinorKey() { return 1; }
const char* GetName() { return "JSConstructEntryStub"; }
};
class ArgumentsAccessStub: public CodeStub {
public:
enum Type {
READ_ELEMENT,
NEW_OBJECT
};
explicit ArgumentsAccessStub(Type type) : type_(type) { }
private:
Type type_;
Major MajorKey() { return ArgumentsAccess; }
int MinorKey() { return type_; }
void Generate(MacroAssembler* masm);
void GenerateReadElement(MacroAssembler* masm);
void GenerateNewObject(MacroAssembler* masm);
const char* GetName() { return "ArgumentsAccessStub"; }
#ifdef DEBUG
void Print() {
PrintF("ArgumentsAccessStub (type %d)\n", type_);
}
#endif
};
class RegExpExecStub: public CodeStub {
public:
RegExpExecStub() { }
private:
Major MajorKey() { return RegExpExec; }
int MinorKey() { return 0; }
void Generate(MacroAssembler* masm);
const char* GetName() { return "RegExpExecStub"; }
#ifdef DEBUG
void Print() {
PrintF("RegExpExecStub\n");
}
#endif
};
class RegExpConstructResultStub: public CodeStub {
public:
RegExpConstructResultStub() { }
private:
Major MajorKey() { return RegExpConstructResult; }
int MinorKey() { return 0; }
void Generate(MacroAssembler* masm);
const char* GetName() { return "RegExpConstructResultStub"; }
#ifdef DEBUG
void Print() {
PrintF("RegExpConstructResultStub\n");
}
#endif
};
class CallFunctionStub: public CodeStub {
public:
CallFunctionStub(int argc, InLoopFlag in_loop, CallFunctionFlags flags)
: argc_(argc), in_loop_(in_loop), flags_(flags) { }
void Generate(MacroAssembler* masm);
private:
int argc_;
InLoopFlag in_loop_;
CallFunctionFlags flags_;
#ifdef DEBUG
void Print() {
PrintF("CallFunctionStub (args %d, in_loop %d, flags %d)\n",
argc_,
static_cast<int>(in_loop_),
static_cast<int>(flags_));
}
#endif
// Minor key encoding in 32 bits with Bitfield <Type, shift, size>.
class InLoopBits: public BitField<InLoopFlag, 0, 1> {};
class FlagBits: public BitField<CallFunctionFlags, 1, 1> {};
class ArgcBits: public BitField<int, 2, 32 - 2> {};
Major MajorKey() { return CallFunction; }
int MinorKey() {
// Encode the parameters in a unique 32 bit value.
return InLoopBits::encode(in_loop_)
| FlagBits::encode(flags_)
| ArgcBits::encode(argc_);
}
InLoopFlag InLoop() { return in_loop_; }
bool ReceiverMightBeValue() {
return (flags_ & RECEIVER_MIGHT_BE_VALUE) != 0;
}
public:
static int ExtractArgcFromMinorKey(int minor_key) {
return ArgcBits::decode(minor_key);
}
};
enum StringIndexFlags {
// Accepts smis or heap numbers.
STRING_INDEX_IS_NUMBER,
// Accepts smis or heap numbers that are valid array indices
// (ECMA-262 15.4). Invalid indices are reported as being out of
// range.
STRING_INDEX_IS_ARRAY_INDEX
};
// Generates code implementing String.prototype.charCodeAt.
//
// Only supports the case when the receiver is a string and the index
// is a number (smi or heap number) that is a valid index into the
// string. Additional index constraints are specified by the
// flags. Otherwise, bails out to the provided labels.
//
// Register usage: |object| may be changed to another string in a way
// that doesn't affect charCodeAt/charAt semantics, |index| is
// preserved, |scratch| and |result| are clobbered.
class StringCharCodeAtGenerator {
public:
StringCharCodeAtGenerator(Register object,
Register index,
Register scratch,
Register result,
Label* receiver_not_string,
Label* index_not_number,
Label* index_out_of_range,
StringIndexFlags index_flags)
: object_(object),
index_(index),
scratch_(scratch),
result_(result),
receiver_not_string_(receiver_not_string),
index_not_number_(index_not_number),
index_out_of_range_(index_out_of_range),
index_flags_(index_flags) {
ASSERT(!scratch_.is(object_));
ASSERT(!scratch_.is(index_));
ASSERT(!scratch_.is(result_));
ASSERT(!result_.is(object_));
ASSERT(!result_.is(index_));
}
// Generates the fast case code. On the fallthrough path |result|
// register contains the result.
void GenerateFast(MacroAssembler* masm);
// Generates the slow case code. Must not be naturally
// reachable. Expected to be put after a ret instruction (e.g., in
// deferred code). Always jumps back to the fast case.
void GenerateSlow(MacroAssembler* masm,
const RuntimeCallHelper& call_helper);
private:
Register object_;
Register index_;
Register scratch_;
Register result_;
Label* receiver_not_string_;
Label* index_not_number_;
Label* index_out_of_range_;
StringIndexFlags index_flags_;
Label call_runtime_;
Label index_not_smi_;
Label got_smi_index_;
Label exit_;
DISALLOW_COPY_AND_ASSIGN(StringCharCodeAtGenerator);
};
// Generates code for creating a one-char string from a char code.
class StringCharFromCodeGenerator {
public:
StringCharFromCodeGenerator(Register code,
Register result)
: code_(code),
result_(result) {
ASSERT(!code_.is(result_));
}
// Generates the fast case code. On the fallthrough path |result|
// register contains the result.
void GenerateFast(MacroAssembler* masm);
// Generates the slow case code. Must not be naturally
// reachable. Expected to be put after a ret instruction (e.g., in
// deferred code). Always jumps back to the fast case.
void GenerateSlow(MacroAssembler* masm,
const RuntimeCallHelper& call_helper);
private:
Register code_;
Register result_;
Label slow_case_;
Label exit_;
DISALLOW_COPY_AND_ASSIGN(StringCharFromCodeGenerator);
};
// Generates code implementing String.prototype.charAt.
//
// Only supports the case when the receiver is a string and the index
// is a number (smi or heap number) that is a valid index into the
// string. Additional index constraints are specified by the
// flags. Otherwise, bails out to the provided labels.
//
// Register usage: |object| may be changed to another string in a way
// that doesn't affect charCodeAt/charAt semantics, |index| is
// preserved, |scratch1|, |scratch2|, and |result| are clobbered.
class StringCharAtGenerator {
public:
StringCharAtGenerator(Register object,
Register index,
Register scratch1,
Register scratch2,
Register result,
Label* receiver_not_string,
Label* index_not_number,
Label* index_out_of_range,
StringIndexFlags index_flags)
: char_code_at_generator_(object,
index,
scratch1,
scratch2,
receiver_not_string,
index_not_number,
index_out_of_range,
index_flags),
char_from_code_generator_(scratch2, result) {}
// Generates the fast case code. On the fallthrough path |result|
// register contains the result.
void GenerateFast(MacroAssembler* masm);
// Generates the slow case code. Must not be naturally
// reachable. Expected to be put after a ret instruction (e.g., in
// deferred code). Always jumps back to the fast case.
void GenerateSlow(MacroAssembler* masm,
const RuntimeCallHelper& call_helper);
private:
StringCharCodeAtGenerator char_code_at_generator_;
StringCharFromCodeGenerator char_from_code_generator_;
DISALLOW_COPY_AND_ASSIGN(StringCharAtGenerator);
};
} } // namespace v8::internal
#endif // V8_CODE_STUBS_H_