AuroraMiddleware/v8
1
0
Fork 0
Code Issues 2 Pull Requests Releases Wiki Activity

A bunch of changes to speed up math on ARM.

Browse Source 
* Identify heap numbers that contain non-Smi int32s and do bit
ops on them without calling the fp hardware or emulation.
* Identify results that are non-Smi int32s and write them into
heap numbers without calling the fp hardware or emulation.
* Do unary minus on heap numbers without going into the runtime
system.
* On add, sub and mul if we have both Smi and heapnumber inputs
to the same operation then convert the Smi to a double and do
the op without going into runtime system.  This also applies
if we have two Smi inputs but the result is not Smi.
Review URL: http://codereview.chromium.org/119241

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2131 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
erik.corry@gmail.com 2009-06-10 10:20:37 +00:00
parent 13e548af1d
commit b7d48f5807
6 changed files with 593 additions and 123 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

658
src/arm/codegen-arm.cc
View File

@ -703,6 +703,7 @@ class GenericBinaryOpStub : public CodeStub {
}
void Generate(MacroAssembler* masm);
void HandleNonSmiBitwiseOp(MacroAssembler* masm);
const char* GetName() {
switch (op_) {
@ -3566,7 +3567,10 @@ void CodeGenerator::VisitUnaryOperation(UnaryOperation* node) {
break;
case Token::SUB: {
UnarySubStub stub;
bool overwrite =
(node->AsBinaryOperation() != NULL &&
node->AsBinaryOperation()->ResultOverwriteAllowed());
UnarySubStub stub(overwrite);
frame_->CallStub(&stub, 0);
break;
}
@ -4336,6 +4340,223 @@ void Reference::SetValue(InitState init_state) {
}
// Count leading zeros in a 32 bit word. On ARM5 and later it uses the clz
// instruction. On pre-ARM5 hardware this routine gives the wrong answer for 0
// (31 instead of 32).
static void CountLeadingZeros(
MacroAssembler* masm,
Register source,
Register scratch,
Register zeros) {
#ifdef __ARM_ARCH_5__
__ clz(zeros, source); // This instruction is only supported after ARM5.
#else
__ mov(zeros, Operand(0));
__ mov(scratch, source);
// Top 16.
__ tst(scratch, Operand(0xffff0000));
__ add(zeros, zeros, Operand(16), LeaveCC, eq);
__ mov(scratch, Operand(scratch, LSL, 16), LeaveCC, eq);
// Top 8.
__ tst(scratch, Operand(0xff000000));
__ add(zeros, zeros, Operand(8), LeaveCC, eq);
__ mov(scratch, Operand(scratch, LSL, 8), LeaveCC, eq);
// Top 4.
__ tst(scratch, Operand(0xf0000000));
__ add(zeros, zeros, Operand(4), LeaveCC, eq);
__ mov(scratch, Operand(scratch, LSL, 4), LeaveCC, eq);
// Top 2.
__ tst(scratch, Operand(0xc0000000));
__ add(zeros, zeros, Operand(2), LeaveCC, eq);
__ mov(scratch, Operand(scratch, LSL, 2), LeaveCC, eq);
// Top bit.
__ tst(scratch, Operand(0x80000000));
__ add(zeros, zeros, Operand(1), LeaveCC, eq);
#endif
}
// Takes a Smi and converts to an IEEE 64 bit floating point value in two
// registers. The format is 1 sign bit, 11 exponent bits (biased 1023) and
// 52 fraction bits (20 in the first word, 32 in the second). Zeros is a
// scratch register. Destroys the source register. No GC occurs during this
// stub so you don't have to set up the frame.
class ConvertToDoubleStub : public CodeStub {
public:
ConvertToDoubleStub(Register result_reg_1,
Register result_reg_2,
Register source_reg,
Register scratch_reg)
: result1_(result_reg_1),
result2_(result_reg_2),
source_(source_reg),
zeros_(scratch_reg) { }
private:
Register result1_;
Register result2_;
Register source_;
Register zeros_;
// Minor key encoding in 16 bits.
class ModeBits: public BitField<OverwriteMode, 0, 2> {};
class OpBits: public BitField<Token::Value, 2, 14> {};
Major MajorKey() { return ConvertToDouble; }
int MinorKey() {
// Encode the parameters in a unique 16 bit value.
return result1_.code() +
(result2_.code() << 4) +
(source_.code() << 8) +
(zeros_.code() << 12);
}
void Generate(MacroAssembler* masm);
const char* GetName() { return "ConvertToDoubleStub"; }
#ifdef DEBUG
void Print() { PrintF("ConvertToDoubleStub\n"); }
#endif
};
void ConvertToDoubleStub::Generate(MacroAssembler* masm) {
Label not_special, done;
// Convert from Smi to integer.
__ mov(source_, Operand(source_, ASR, kSmiTagSize));
// Move sign bit from source to destination. This works because the sign bit
// in the exponent word of the double has the same position and polarity as
// the 2's complement sign bit in a Smi.
ASSERT(HeapNumber::kSignMask == 0x80000000u);
__ and_(result1_, source_, Operand(HeapNumber::kSignMask), SetCC);
// Subtract from 0 if source was negative.
__ rsb(source_, source_, Operand(0), LeaveCC, ne);
__ cmp(source_, Operand(1));
__ b(gt, &not_special);
// We have -1, 0 or 1, which we treat specially.
__ cmp(source_, Operand(0));
// For 1 or -1 we need to or in the 0 exponent (biased to 1023).
static const uint32_t exponent_word_for_1 =
HeapNumber::kExponentBias << HeapNumber::kExponentShift;
__ orr(result1_, result1_, Operand(exponent_word_for_1), LeaveCC, ne);
// 1, 0 and -1 all have 0 for the second word.
__ mov(result2_, Operand(0));
__ jmp(&done);
__ bind(&not_special);
// Count leading zeros. Uses result2 for a scratch register on pre-ARM5.
// Gets the wrong answer for 0, but we already checked for that case above.
CountLeadingZeros(masm, source_, result2_, zeros_);
// Compute exponent and or it into the exponent register.
// We use result2 as a scratch register here.
__ rsb(result2_, zeros_, Operand(31 + HeapNumber::kExponentBias));
__ orr(result1_,
result1_,
Operand(result2_, LSL, HeapNumber::kExponentShift));
// Shift up the source chopping the top bit off.
__ add(zeros_, zeros_, Operand(1));
// This wouldn't work for 1.0 or -1.0 as the shift would be 32 which means 0.
__ mov(source_, Operand(source_, LSL, zeros_));
// Compute lower part of fraction (last 12 bits).
__ mov(result2_, Operand(source_, LSL, HeapNumber::kMantissaBitsInTopWord));
// And the top (top 20 bits).
__ orr(result1_,
result1_,
Operand(source_, LSR, 32 - HeapNumber::kMantissaBitsInTopWord));
__ bind(&done);
__ Ret();
}
// This stub can convert a signed int32 to a heap number (double). It does
// not work for int32s that are in Smi range! No GC occurs during this stub
// so you don't have to set up the frame.
class WriteInt32ToHeapNumberStub : public CodeStub {
public:
WriteInt32ToHeapNumberStub(Register the_int,
Register the_heap_number,
Register scratch)
: the_int_(the_int),
the_heap_number_(the_heap_number),
scratch_(scratch) { }
private:
Register the_int_;
Register the_heap_number_;
Register scratch_;
// Minor key encoding in 16 bits.
class ModeBits: public BitField<OverwriteMode, 0, 2> {};
class OpBits: public BitField<Token::Value, 2, 14> {};
Major MajorKey() { return WriteInt32ToHeapNumber; }
int MinorKey() {
// Encode the parameters in a unique 16 bit value.
return the_int_.code() +
(the_heap_number_.code() << 4) +
(scratch_.code() << 8);
}
void Generate(MacroAssembler* masm);
const char* GetName() { return "WriteInt32ToHeapNumberStub"; }
#ifdef DEBUG
void Print() { PrintF("WriteInt32ToHeapNumberStub\n"); }
#endif
};
// See comment for class.
void WriteInt32ToHeapNumberStub::Generate(MacroAssembler *masm) {
Label max_negative_int;
// the_int_ has the answer which is a signed int32 but not a Smi.
// We test for the special value that has a different exponent. This test
// has the neat side effect of setting the flags according to the sign.
ASSERT(HeapNumber::kSignMask == 0x80000000u);
__ cmp(the_int_, Operand(0x80000000));
__ b(eq, &max_negative_int);
// Set up the correct exponent in scratch_. All non-Smi int32s have the same.
// A non-Smi integer is 1.xxx * 2^30 so the exponent is 30 (biased).
uint32_t non_smi_exponent =
(HeapNumber::kExponentBias + 30) << HeapNumber::kExponentShift;
__ mov(scratch_, Operand(non_smi_exponent));
// Set the sign bit in scratch_ if the value was negative.
__ orr(scratch_, scratch_, Operand(HeapNumber::kSignMask), LeaveCC, cs);
// Subtract from 0 if the value was negative.
__ rsb(the_int_, the_int_, Operand(0), LeaveCC, cs);
// We should be masking the implict first digit of the mantissa away here,
// but it just ends up combining harmlessly with the last digit of the
// exponent that happens to be 1. The sign bit is 0 so we shift 10 to get
// the most significant 1 to hit the last bit of the 12 bit sign and exponent.
ASSERT(((1 << HeapNumber::kExponentShift) & non_smi_exponent) != 0);
const int shift_distance = HeapNumber::kNonMantissaBitsInTopWord - 2;
__ orr(scratch_, scratch_, Operand(the_int_, LSR, shift_distance));
__ str(scratch_, FieldMemOperand(the_heap_number_,
HeapNumber::kExponentOffset));
__ mov(scratch_, Operand(the_int_, LSL, 32 - shift_distance));
__ str(scratch_, FieldMemOperand(the_heap_number_,
HeapNumber::kMantissaOffset));
__ Ret();
__ bind(&max_negative_int);
// The max negative int32 is stored as a positive number in the mantissa of
// a double because it uses a sign bit instead of using two's complement.
// The actual mantissa bits stored are all 0 because the implicit most
// significant 1 bit is not stored.
non_smi_exponent += 1 << HeapNumber::kExponentShift;
__ mov(ip, Operand(HeapNumber::kSignMask | non_smi_exponent));
__ str(ip, FieldMemOperand(the_heap_number_, HeapNumber::kExponentOffset));
__ mov(ip, Operand(0));
__ str(ip, FieldMemOperand(the_heap_number_, HeapNumber::kMantissaOffset));
__ Ret();
}
// Allocates a heap number or jumps to the label if the young space is full and
// a scavenge is needed.
static void AllocateHeapNumber(
MacroAssembler* masm,
Label* need_gc, // Jump here if young space is full.
@ -4372,58 +4593,121 @@ static void AllocateHeapNumber(
}
// Checks that the object register (which is assumed not to be a Smi) points to
// a heap number. Jumps to the label if it is not.
void CheckForHeapNumber(MacroAssembler* masm,
Register object,
Register scratch,
Label* slow) {
// Get map of object into scratch.
__ ldr(scratch, FieldMemOperand(object, HeapObject::kMapOffset));
// Get type of object into scratch.
__ ldrb(scratch, FieldMemOperand(scratch, Map::kInstanceTypeOffset));
__ cmp(scratch, Operand(HEAP_NUMBER_TYPE));
__ b(ne, slow);
}
// We fall into this code if the operands were Smis, but the result was
// not (eg. overflow). We branch into this code (to the not_smi label) if
// the operands were not both Smi.
// the operands were not both Smi. The operands are in r0 and r1. In order
// to call the C-implemented binary fp operation routines we need to end up
// with the double precision floating point operands in r0 and r1 (for the
// value in r1) and r2 and r3 (for the value in r0).
static void HandleBinaryOpSlowCases(MacroAssembler* masm,
Label* not_smi,
const Builtins::JavaScript& builtin,
Token::Value operation,
OverwriteMode mode) {
Label slow;
Label slow, slow_pop_2_first, do_the_call;
Label r0_is_smi, r1_is_smi, finished_loading_r0, finished_loading_r1;
// Smi-smi case (overflow).
// Since both are Smis there is no heap number to overwrite, so allocate.
// The new heap number is in r5. r6 and r7 are scratch.
AllocateHeapNumber(masm, &slow, r5, r6, r7);
// Write Smi from r0 to r3 and r2 in double format. r6 is scratch.
ConvertToDoubleStub stub1(r3, r2, r0, r6);
__ push(lr);
__ Call(stub1.GetCode(), RelocInfo::CODE_TARGET);
// Write Smi from r1 to r1 and r0 in double format. r6 is scratch.
__ mov(r7, Operand(r1));
ConvertToDoubleStub stub2(r1, r0, r7, r6);
__ Call(stub2.GetCode(), RelocInfo::CODE_TARGET);
__ pop(lr);
__ jmp(&do_the_call); // Tail call. No return.
// We jump to here if something goes wrong (one param is not a number of any
// sort or new-space allocation fails).
__ bind(&slow);
__ push(r1);
__ push(r0);
__ mov(r0, Operand(1)); // Set number of arguments.
__ InvokeBuiltin(builtin, JUMP_JS); // Tail call.
__ InvokeBuiltin(builtin, JUMP_JS); // Tail call. No return.
// We branch here if at least one of r0 and r1 is not a Smi.
__ bind(not_smi);
__ tst(r0, Operand(kSmiTagMask));
__ b(eq, &slow); // We can't handle a Smi-double combination yet.
__ tst(r1, Operand(kSmiTagMask));
__ b(eq, &slow); // We can't handle a Smi-double combination yet.
// Get map of r0 into r2.
__ ldr(r2, FieldMemOperand(r0, HeapObject::kMapOffset));
// Get type of r0 into r3.
__ ldrb(r3, FieldMemOperand(r2, Map::kInstanceTypeOffset));
__ cmp(r3, Operand(HEAP_NUMBER_TYPE));
__ b(ne, &slow);
// Get type of r1 into r3.
__ ldr(r3, FieldMemOperand(r1, HeapObject::kMapOffset));
// Check they are both the same map (heap number map).
__ cmp(r2, r3);
__ b(ne, &slow);
// Both are doubles.
// Calling convention says that second double is in r2 and r3.
__ ldr(r2, FieldMemOperand(r0, HeapNumber::kValueOffset));
__ ldr(r3, FieldMemOperand(r0, HeapNumber::kValueOffset + kPointerSize));
if (mode == NO_OVERWRITE) {
// Get address of new heap number into r5.
// In the case where there is no chance of an overwritable float we may as
// well do the allocation immediately while r0 and r1 are untouched.
AllocateHeapNumber(masm, &slow, r5, r6, r7);
}
// Move r0 to a double in r2-r3.
__ tst(r0, Operand(kSmiTagMask));
__ b(eq, &r0_is_smi); // It's a Smi so don't check it's a heap number.
CheckForHeapNumber(masm, r0, r4, &slow);
if (mode == OVERWRITE_RIGHT) {
__ mov(r5, Operand(r0)); // Overwrite this heap number.
}
// Calling convention says that second double is in r2 and r3.
__ ldr(r2, FieldMemOperand(r0, HeapNumber::kMantissaOffset));
__ ldr(r3, FieldMemOperand(r0, HeapNumber::kExponentOffset));
__ jmp(&finished_loading_r0);
__ bind(&r0_is_smi);
if (mode == OVERWRITE_RIGHT) {
// We can't overwrite a Smi so get address of new heap number into r5.
AllocateHeapNumber(masm, &slow, r5, r6, r7);
}
// Write Smi from r0 to r3 and r2 in double format.
__ mov(r7, Operand(r0));
ConvertToDoubleStub stub3(r3, r2, r7, r6);
__ push(lr);
__ push(r5);
} else if (mode == OVERWRITE_LEFT) {
__ push(lr);
__ push(r1);
} else {
ASSERT(mode == OVERWRITE_RIGHT);
__ push(lr);
__ push(r0);
__ Call(stub3.GetCode(), RelocInfo::CODE_TARGET);
__ pop(lr);
__ bind(&finished_loading_r0);
// Move r1 to a double in r0-r1.
__ tst(r1, Operand(kSmiTagMask));
__ b(eq, &r1_is_smi); // It's a Smi so don't check it's a heap number.
CheckForHeapNumber(masm, r1, r4, &slow);
if (mode == OVERWRITE_LEFT) {
__ mov(r5, Operand(r1)); // Overwrite this heap number.
}
// Calling convention says that first double is in r0 and r1.
__ ldr(r0, FieldMemOperand(r1, HeapNumber::kValueOffset));
__ ldr(r1, FieldMemOperand(r1, HeapNumber::kValueOffset + kPointerSize));
__ ldr(r0, FieldMemOperand(r1, HeapNumber::kMantissaOffset));
__ ldr(r1, FieldMemOperand(r1, HeapNumber::kExponentOffset));
__ jmp(&finished_loading_r1);
__ bind(&r1_is_smi);
if (mode == OVERWRITE_LEFT) {
// We can't overwrite a Smi so get address of new heap number into r5.
AllocateHeapNumber(masm, &slow, r5, r6, r7);
}
// Write Smi from r1 to r1 and r0 in double format.
__ mov(r7, Operand(r1));
ConvertToDoubleStub stub4(r1, r0, r7, r6);
__ push(lr);
__ Call(stub4.GetCode(), RelocInfo::CODE_TARGET);
__ pop(lr);
__ bind(&finished_loading_r1);
__ bind(&do_the_call);
// r0: Left value (least significant part of mantissa).
// r1: Left value (sign, exponent, top of mantissa).
// r2: Right value (least significant part of mantissa).
// r3: Right value (sign, exponent, top of mantissa).
// r5: Address of heap number for result.
__ push(lr); // For later.
__ push(r5); // Address of heap number that is answer.
// Call C routine that may not cause GC or other trouble.
__ mov(r5, Operand(ExternalReference::double_fp_operation(operation)));
__ Call(r5);
@ -4437,8 +4721,8 @@ static void HandleBinaryOpSlowCases(MacroAssembler* masm,
__ stc(p1, cr8, MemOperand(r5, HeapNumber::kValueOffset));
#else
// Double returned in registers 0 and 1.
__ str(r0, FieldMemOperand(r4, HeapNumber::kValueOffset));
__ str(r1, FieldMemOperand(r4, HeapNumber::kValueOffset + kPointerSize));
__ str(r0, FieldMemOperand(r4, HeapNumber::kMantissaOffset));
__ str(r1, FieldMemOperand(r4, HeapNumber::kExponentOffset));
#endif
__ mov(r0, Operand(r4));
// And we are done.
@ -4446,6 +4730,183 @@ static void HandleBinaryOpSlowCases(MacroAssembler* masm,
}
// Tries to get a signed int32 out of a double precision floating point heap
// number. Rounds towards 0. Only succeeds for doubles that are in the ranges
// -0x7fffffff to -0x40000000 or 0x40000000 to 0x7fffffff. This corresponds
// almost to the range of signed int32 values that are not Smis. Jumps to the
// label if the double isn't in the range it can cope with.
static void GetInt32(MacroAssembler* masm,
Register source,
Register dest,
Register scratch,
Label* slow) {
Register scratch2 = dest;
// Get exponent word.
__ ldr(scratch, FieldMemOperand(source, HeapNumber::kExponentOffset));
// Get exponent alone in scratch2.
__ and_(scratch2, scratch, Operand(HeapNumber::kExponentMask));
// Check whether the exponent matches a 32 bit signed int that is not a Smi.
// A non-Smi integer is 1.xxx * 2^30 so the exponent is 30 (biased).
const uint32_t non_smi_exponent =
(HeapNumber::kExponentBias + 30) << HeapNumber::kExponentShift;
__ cmp(scratch2, Operand(non_smi_exponent));
// If not, then we go slow.
__ b(ne, slow);
// Get the top bits of the mantissa.
__ and_(scratch2, scratch, Operand(HeapNumber::kMantissaMask));
// Put back the implicit 1.
__ orr(scratch2, scratch2, Operand(1 << HeapNumber::kExponentShift));
// Shift up the mantissa bits to take up the space the exponent used to take.
// We just orred in the implicit bit so that took care of one and we want to
// leave the sign bit 0 so we subtract 2 bits from the shift distance.
const int shift_distance = HeapNumber::kNonMantissaBitsInTopWord - 2;
__ mov(scratch2, Operand(scratch2, LSL, shift_distance));
// Put sign in zero flag.
__ tst(scratch, Operand(HeapNumber::kSignMask));
// Get the second half of the double.
__ ldr(scratch, FieldMemOperand(source, HeapNumber::kMantissaOffset));
// Shift down 22 bits to get the last 10 bits.
__ orr(dest, scratch2, Operand(scratch, LSR, 32 - shift_distance));
// Fix sign if sign bit was set.
__ rsb(dest, dest, Operand(0), LeaveCC, ne);
}
// For bitwise ops where the inputs are not both Smis we here try to determine
// whether both inputs are either Smis or at least heap numbers that can be
// represented by a 32 bit signed value. We truncate towards zero as required
// by the ES spec. If this is the case we do the bitwise op and see if the
// result is a Smi. If so, great, otherwise we try to find a heap number to
// write the answer into (either by allocating or by overwriting).
// On entry the operands are in r0 and r1. On exit the answer is in r0.
void GenericBinaryOpStub::HandleNonSmiBitwiseOp(MacroAssembler* masm) {
Label slow, result_not_a_smi;
Label r0_is_smi, r1_is_smi;
Label done_checking_r0, done_checking_r1;
__ tst(r1, Operand(kSmiTagMask));
__ b(eq, &r1_is_smi); // It's a Smi so don't check it's a heap number.
CheckForHeapNumber(masm, r1, r4, &slow);
GetInt32(masm, r1, r3, r4, &slow);
__ jmp(&done_checking_r1);
__ bind(&r1_is_smi);
__ mov(r3, Operand(r1, ASR, 1));
__ bind(&done_checking_r1);
__ tst(r0, Operand(kSmiTagMask));
__ b(eq, &r0_is_smi); // It's a Smi so don't check it's a heap number.
CheckForHeapNumber(masm, r0, r4, &slow);
GetInt32(masm, r0, r2, r4, &slow);
__ jmp(&done_checking_r0);
__ bind(&r0_is_smi);
__ mov(r2, Operand(r0, ASR, 1));
__ bind(&done_checking_r0);
// r0 and r1: Original operands (Smi or heap numbers).
// r2 and r3: Signed int32 operands.
switch (op_) {
case Token::BIT_OR: __ orr(r2, r2, Operand(r3)); break;
case Token::BIT_XOR: __ eor(r2, r2, Operand(r3)); break;
case Token::BIT_AND: __ and_(r2, r2, Operand(r3)); break;
case Token::SAR:
// Use only the 5 least significant bits of the shift count.
__ and_(r2, r2, Operand(0x1f));
__ mov(r2, Operand(r3, ASR, r2));
break;
case Token::SHR:
// Use only the 5 least significant bits of the shift count.
__ and_(r2, r2, Operand(0x1f));
__ mov(r2, Operand(r3, LSR, r2), SetCC);
// SHR is special because it is required to produce a positive answer.
// The code below for writing into heap numbers isn't capable of writing
// the register as an unsigned int so we go to slow case if we hit this
// case.
__ b(mi, &slow);
break;
case Token::SHL:
// Use only the 5 least significant bits of the shift count.
__ and_(r2, r2, Operand(0x1f));
__ mov(r2, Operand(r3, LSL, r2));
break;
default: UNREACHABLE();
}
// check that the *signed* result fits in a smi
__ add(r3, r2, Operand(0x40000000), SetCC);
__ b(mi, &result_not_a_smi);
__ mov(r0, Operand(r2, LSL, kSmiTagSize));
__ Ret();
Label have_to_allocate, got_a_heap_number;
__ bind(&result_not_a_smi);
switch (mode_) {
case OVERWRITE_RIGHT: {
__ tst(r0, Operand(kSmiTagMask));
__ b(eq, &have_to_allocate);
__ mov(r5, Operand(r0));
break;
}
case OVERWRITE_LEFT: {
__ tst(r1, Operand(kSmiTagMask));
__ b(eq, &have_to_allocate);
__ mov(r5, Operand(r1));
break;
}
case NO_OVERWRITE: {
// Get a new heap number in r5. r6 and r7 are scratch.
AllocateHeapNumber(masm, &slow, r5, r6, r7);
}
default: break;
}
__ bind(&got_a_heap_number);
// r2: Answer as signed int32.
// r5: Heap number to write answer into.
// Nothing can go wrong now, so move the heap number to r0, which is the
// result.
__ mov(r0, Operand(r5));
// Tail call that writes the int32 in r2 to the heap number in r0, using
// r3 as scratch. r0 is preserved and returned.
WriteInt32ToHeapNumberStub stub(r2, r0, r3);
__ Jump(stub.GetCode(), RelocInfo::CODE_TARGET);
if (mode_ != NO_OVERWRITE) {
__ bind(&have_to_allocate);
// Get a new heap number in r5. r6 and r7 are scratch.
AllocateHeapNumber(masm, &slow, r5, r6, r7);
__ jmp(&got_a_heap_number);
}
// If all else failed then we go to the runtime system.
__ bind(&slow);
__ push(r1); // restore stack
__ push(r0);
__ mov(r0, Operand(1)); // 1 argument (not counting receiver).
switch (op_) {
case Token::BIT_OR:
__ InvokeBuiltin(Builtins::BIT_OR, JUMP_JS);
break;
case Token::BIT_AND:
__ InvokeBuiltin(Builtins::BIT_AND, JUMP_JS);
break;
case Token::BIT_XOR:
__ InvokeBuiltin(Builtins::BIT_XOR, JUMP_JS);
break;
case Token::SAR:
__ InvokeBuiltin(Builtins::SAR, JUMP_JS);
break;
case Token::SHR:
__ InvokeBuiltin(Builtins::SHR, JUMP_JS);
break;
case Token::SHL:
__ InvokeBuiltin(Builtins::SHL, JUMP_JS);
break;
default:
UNREACHABLE();
}
}
void GenericBinaryOpStub::Generate(MacroAssembler* masm) {
// r1 : x
// r0 : y
@ -4524,7 +4985,10 @@ void GenericBinaryOpStub::Generate(MacroAssembler* masm) {
case Token::BIT_OR:
case Token::BIT_AND:
case Token::BIT_XOR: {
case Token::BIT_XOR:
case Token::SAR:
case Token::SHR:
case Token::SHL: {
Label slow;
ASSERT(kSmiTag == 0); // adjust code below
__ tst(r2, Operand(kSmiTagMask));
@ -4533,84 +4997,47 @@ void GenericBinaryOpStub::Generate(MacroAssembler* masm) {
case Token::BIT_OR: __ orr(r0, r0, Operand(r1)); break;
case Token::BIT_AND: __ and_(r0, r0, Operand(r1)); break;
case Token::BIT_XOR: __ eor(r0, r0, Operand(r1)); break;
default: UNREACHABLE();
}
__ Ret();
__ bind(&slow);
__ push(r1); // restore stack
__ push(r0);
__ mov(r0, Operand(1)); // 1 argument (not counting receiver).
switch (op_) {
case Token::BIT_OR:
__ InvokeBuiltin(Builtins::BIT_OR, JUMP_JS);
case Token::SAR:
// Remove tags from right operand.
__ mov(r2, Operand(r0, ASR, kSmiTagSize)); // y
// Use only the 5 least significant bits of the shift count.
__ and_(r2, r2, Operand(0x1f));
__ mov(r0, Operand(r1, ASR, r2));
// Smi tag result.
__ and_(r0, r0, Operand(~kSmiTagMask));
break;
case Token::BIT_AND:
__ InvokeBuiltin(Builtins::BIT_AND, JUMP_JS);
break;
case Token::BIT_XOR:
__ InvokeBuiltin(Builtins::BIT_XOR, JUMP_JS);
break;
default:
UNREACHABLE();
}
break;
}
case Token::SHL:
case Token::SHR:
case Token::SAR: {
Label slow;
ASSERT(kSmiTag == 0); // adjust code below
__ tst(r2, Operand(kSmiTagMask));
__ b(ne, &slow);
// remove tags from operands (but keep sign)
// Remove tags from operands. We can't do this on a 31 bit number
// because then the 0s get shifted into bit 30 instead of bit 31.
__ mov(r3, Operand(r1, ASR, kSmiTagSize)); // x
__ mov(r2, Operand(r0, ASR, kSmiTagSize)); // y
// use only the 5 least significant bits of the shift count
// Use only the 5 least significant bits of the shift count.
__ and_(r2, r2, Operand(0x1f));
// perform operation
switch (op_) {
case Token::SAR:
__ mov(r3, Operand(r3, ASR, r2));
// no checks of result necessary
break;
case Token::SHR:
__ mov(r3, Operand(r3, LSR, r2));
// check that the *unsigned* result fits in a smi
// neither of the two high-order bits can be set:
// - 0x80000000: high bit would be lost when smi tagging
// - 0x40000000: this number would convert to negative when
// smi tagging these two cases can only happen with shifts
// by 0 or 1 when handed a valid smi
__ and_(r2, r3, Operand(0xc0000000), SetCC);
// Unsigned shift is not allowed to produce a negative number, so
// check the sign bit and the sign bit after Smi tagging.
__ tst(r3, Operand(0xc0000000));
__ b(ne, &slow);
// Smi tag result.
__ mov(r0, Operand(r3, LSL, kSmiTagSize));
break;
case Token::SHL:
// Remove tags from operands.
__ mov(r3, Operand(r1, ASR, kSmiTagSize)); // x
__ mov(r2, Operand(r0, ASR, kSmiTagSize)); // y
// Use only the 5 least significant bits of the shift count.
__ and_(r2, r2, Operand(0x1f));
__ mov(r3, Operand(r3, LSL, r2));
// check that the *signed* result fits in a smi
// Check that the signed result fits in a Smi.
__ add(r2, r3, Operand(0x40000000), SetCC);
__ b(mi, &slow);
break;
default: UNREACHABLE();
}
// tag result and store it in r0
ASSERT(kSmiTag == 0); // adjust code below
__ mov(r0, Operand(r3, LSL, kSmiTagSize));
__ Ret();
// slow case
__ bind(&slow);
__ push(r1); // restore stack
__ push(r0);
__ mov(r0, Operand(1)); // 1 argument (not counting receiver).
switch (op_) {
case Token::SAR: __ InvokeBuiltin(Builtins::SAR, JUMP_JS); break;
case Token::SHR: __ InvokeBuiltin(Builtins::SHR, JUMP_JS); break;
case Token::SHL: __ InvokeBuiltin(Builtins::SHL, JUMP_JS); break;
break;
default: UNREACHABLE();
}
__ Ret();
__ bind(&slow);
HandleNonSmiBitwiseOp(masm);
break;
}
@ -4642,10 +5069,11 @@ void UnarySubStub::Generate(MacroAssembler* masm) {
Label undo;
Label slow;
Label done;
Label not_smi;
// Enter runtime system if the value is not a smi.
__ tst(r0, Operand(kSmiTagMask));
__ b(ne, &slow);
__ b(ne, &not_smi);
// Enter runtime system if the value of the expression is zero
// to make sure that we switch between 0 and -0.
@ -4657,19 +5085,35 @@ void UnarySubStub::Generate(MacroAssembler* masm) {
__ rsb(r1, r0, Operand(0), SetCC);
__ b(vs, &slow);
// If result is a smi we are done.
__ tst(r1, Operand(kSmiTagMask));
__ mov(r0, Operand(r1), LeaveCC, eq); // conditionally set r0 to result
__ b(eq, &done);
__ mov(r0, Operand(r1)); // Set r0 to result.
__ StubReturn(1);
// Enter runtime system.
__ bind(&slow);
__ push(r0);
__ mov(r0, Operand(0)); // set number of arguments
__ mov(r0, Operand(0)); // Set number of arguments.
__ InvokeBuiltin(Builtins::UNARY_MINUS, JUMP_JS);
__ bind(&done);
__ StubReturn(1);
__ bind(&not_smi);
CheckForHeapNumber(masm, r0, r1, &slow);
// r0 is a heap number. Get a new heap number in r1.
if (overwrite_) {
__ ldr(r2, FieldMemOperand(r0, HeapNumber::kExponentOffset));
__ eor(r2, r2, Operand(HeapNumber::kSignMask)); // Flip sign.
__ str(r2, FieldMemOperand(r0, HeapNumber::kExponentOffset));
} else {
AllocateHeapNumber(masm, &slow, r1, r2, r3);
__ ldr(r2, FieldMemOperand(r0, HeapNumber::kMantissaOffset));
__ str(r2, FieldMemOperand(r1, HeapNumber::kMantissaOffset));
__ ldr(r2, FieldMemOperand(r0, HeapNumber::kExponentOffset));
__ eor(r2, r2, Operand(HeapNumber::kSignMask)); // Flip sign.
__ str(r2, FieldMemOperand(r1, HeapNumber::kExponentOffset));
__ mov(r0, Operand(r1));
}
__ StubReturn(1);
}

2
src/code-stubs.h
View File

@ -41,6 +41,8 @@ class CodeStub BASE_EMBEDDED {
SmiOp,
Compare,
RecordWrite, // Last stub that allows stub calls inside.
ConvertToDouble,
WriteInt32ToHeapNumber,
StackCheck,
UnarySub,
RevertToNumber,

6
src/codegen.h
View File

@ -230,11 +230,13 @@ class StackCheckStub : public CodeStub {
class UnarySubStub : public CodeStub {
public:
UnarySubStub() { }
explicit UnarySubStub(bool overwrite)
: overwrite_(overwrite) { }
private:
bool overwrite_;
Major MajorKey() { return UnarySub; }
int MinorKey() { return 0; }
int MinorKey() { return overwrite_ ? 1 : 0; }
void Generate(MacroAssembler* masm);
const char* GetName() { return "UnarySubStub"; }

2
src/d8.js
View File

@ -25,8 +25,6 @@
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// How crappy is it that I have to implement completely basic stuff
// like this myself? Answer: very.
String.prototype.startsWith = function (str) {
if (str.length > this.length)
return false;

23
src/ia32/codegen-ia32.cc
View File

@ -5057,7 +5057,10 @@ void CodeGenerator::VisitUnaryOperation(UnaryOperation* node) {
break;
case Token::SUB: {
UnarySubStub stub;
bool overwrite =
(node->AsBinaryOperation() != NULL &&
node->AsBinaryOperation()->ResultOverwriteAllowed());
UnarySubStub stub(overwrite);
// TODO(1222589): remove dependency of TOS being cached inside stub
Result operand = frame_->Pop();
Result answer = frame_->CallStub(&stub, &operand);
@ -6594,13 +6597,21 @@ void UnarySubStub::Generate(MacroAssembler* masm) {
__ mov(edx, FieldOperand(eax, HeapObject::kMapOffset));
__ cmp(edx, Factory::heap_number_map());
__ j(not_equal, &slow);
if (overwrite_) {
__ mov(edx, FieldOperand(eax, HeapNumber::kExponentOffset));
__ xor_(edx, HeapNumber::kSignMask); // Flip sign.
__ mov(FieldOperand(eax, HeapNumber::kExponentOffset), edx);
} else {
__ mov(edx, Operand(eax));
// edx: operand
FloatingPointHelper::AllocateHeapNumber(masm, &undo, ebx, ecx);
// eax: allocated 'empty' number
__ fld_d(FieldOperand(edx, HeapNumber::kValueOffset));
__ fchs();
__ fstp_d(FieldOperand(eax, HeapNumber::kValueOffset));
__ mov(ecx, FieldOperand(edx, HeapNumber::kExponentOffset));
__ xor_(ecx, HeapNumber::kSignMask); // Flip sign.
__ mov(FieldOperand(eax, HeapNumber::kExponentOffset), ecx);
__ mov(ecx, FieldOperand(edx, HeapNumber::kMantissaOffset));
__ mov(FieldOperand(eax, HeapNumber::kMantissaOffset), ecx);
}
__ bind(&done);
@ -6744,7 +6755,7 @@ void CompareStub::Generate(MacroAssembler* masm) {
// The representation of NaN values has all exponent bits (52..62) set,
// and not all mantissa bits (0..51) clear.
// Read top bits of double representation (second word of value).
__ mov(eax, FieldOperand(edx, HeapNumber::kValueOffset + kPointerSize));
__ mov(eax, FieldOperand(edx, HeapNumber::kExponentOffset));
// Test that exponent bits are all set.
__ not_(eax);
__ test(eax, Immediate(0x7ff00000));
@ -6754,7 +6765,7 @@ void CompareStub::Generate(MacroAssembler* masm) {
// Shift out flag and all exponent bits, retaining only mantissa.
__ shl(eax, 12);
// Or with all low-bits of mantissa.
__ or_(eax, FieldOperand(edx, HeapNumber::kValueOffset));
__ or_(eax, FieldOperand(edx, HeapNumber::kMantissaOffset));
// Return zero equal if all bits in mantissa is zero (it's an Infinity)
// and non-zero if not (it's a NaN).
__ ret(0);

13
src/objects.h
View File

@ -1162,8 +1162,21 @@ class HeapNumber: public HeapObject {
// Layout description.
static const int kValueOffset = HeapObject::kHeaderSize;
// IEEE doubles are two 32 bit words. The first is just mantissa, the second
// is a mixture of sign, exponent and mantissa. This is the ordering on a
// little endian machine with little endian double word ordering.
static const int kMantissaOffset = kValueOffset;
static const int kExponentOffset = kValueOffset + 4;
static const int kSize = kValueOffset + kDoubleSize;
static const uint32_t kSignMask = 0x80000000u;
static const uint32_t kExponentMask = 0x7ff00000u;
static const uint32_t kMantissaMask = 0xfffffu;
static const int kExponentBias = 1023;
static const int kExponentShift = 20;
static const int kMantissaBitsInTopWord = 20;
static const int kNonMantissaBitsInTopWord = 12;
private:
DISALLOW_IMPLICIT_CONSTRUCTORS(HeapNumber);
};