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Commit 76e3e2af authored by erik.corry@gmail.com's avatar erik.corry@gmail.com
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ARM: Handle bitwise operations with literal Smi for 32bits integers without... 

ARM: Handle bitwise operations with literal Smi for 32bits integers without calling the GenericBinaryOpStub.  Refactored and updated the routine to convert a signed int to a double.  This is a commit of http://codereview.chromium.org/3247008 for Rodolph Perfetta.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5401 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
parent 5628d3c4
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Showing with 358 additions and 143 deletions
src/arm/code-stubs-arm.cc
View file @ 76e3e2af
......@@ -1463,95 +1463,6 @@ void GenericBinaryOpStub::HandleBinaryOpSlowCases(
}
// Tries to get a signed int32 out of a double precision floating point heap
// number. Rounds towards 0. Fastest 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 'slow' if the double isn't in the range -0x80000000.0 to 0x80000000.0
// (excluding the endpoints).
static void GetInt32(MacroAssembler* masm,
Register source,
Register dest,
Register scratch,
Register scratch2,
Label* slow) {
Label right_exponent, done;
// Get exponent word.
__ ldr(scratch, FieldMemOperand(source, HeapNumber::kExponentOffset));
// Get exponent alone in scratch2.
__ Ubfx(scratch2,
scratch,
HeapNumber::kExponentShift,
HeapNumber::kExponentBits);
// Load dest with zero. We use this either for the final shift or
// for the answer.
__ mov(dest, Operand(0));
// 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). This is
// the exponent that we are fastest at and also the highest exponent we can
// handle here.
const uint32_t non_smi_exponent = HeapNumber::kExponentBias + 30;
// The non_smi_exponent, 0x41d, is too big for ARM's immediate field so we
// split it up to avoid a constant pool entry. You can't do that in general
// for cmp because of the overflow flag, but we know the exponent is in the
// range 0-2047 so there is no overflow.
int fudge_factor = 0x400;
__ sub(scratch2, scratch2, Operand(fudge_factor));
__ cmp(scratch2, Operand(non_smi_exponent - fudge_factor));
// If we have a match of the int32-but-not-Smi exponent then skip some logic.
__ b(eq, &right_exponent);
// If the exponent is higher than that then go to slow case. This catches
// numbers that don't fit in a signed int32, infinities and NaNs.
__ b(gt, slow);
// We know the exponent is smaller than 30 (biased). If it is less than
// 0 (biased) then the number is smaller in magnitude than 1.0 * 2^0, ie
// it rounds to zero.
const uint32_t zero_exponent = HeapNumber::kExponentBias + 0;
__ sub(scratch2, scratch2, Operand(zero_exponent - fudge_factor), SetCC);
// Dest already has a Smi zero.
__ b(lt, &done);
if (!CpuFeatures::IsSupported(VFP3)) {
// We have an exponent between 0 and 30 in scratch2. Subtract from 30 to
// get how much to shift down.
__ rsb(dest, scratch2, Operand(30));
}
__ bind(&right_exponent);
if (CpuFeatures::IsSupported(VFP3)) {
CpuFeatures::Scope scope(VFP3);
// ARMv7 VFP3 instructions implementing double precision to integer
// conversion using round to zero.
__ ldr(scratch2, FieldMemOperand(source, HeapNumber::kMantissaOffset));
__ vmov(d7, scratch2, scratch);
__ vcvt_s32_f64(s15, d7);
__ vmov(dest, s15);
} else {
// 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. For some exponents we don't
// actually need this because the bits get shifted out again, but
// it's probably slower to test than just to do it.
__ ldr(scratch, FieldMemOperand(source, HeapNumber::kMantissaOffset));
// Shift down 22 bits to get the last 10 bits.
__ orr(scratch, scratch2, Operand(scratch, LSR, 32 - shift_distance));
// Move down according to the exponent.
__ mov(dest, Operand(scratch, LSR, dest));
// Fix sign if sign bit was set.
__ rsb(dest, dest, Operand(0), LeaveCC, ne);
}
__ bind(&done);
}
// 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
......@@ -1574,7 +1485,7 @@ void GenericBinaryOpStub::HandleNonSmiBitwiseOp(MacroAssembler* masm,
__ ldr(r4, FieldMemOperand(lhs, HeapNumber::kMapOffset));
__ cmp(r4, heap_number_map);
__ b(ne, &slow);
GetInt32(masm, lhs, r3, r5, r4, &slow);
__ ConvertToInt32(lhs, r3, r5, r4, &slow);
__ jmp(&done_checking_lhs);
__ bind(&lhs_is_smi);
__ mov(r3, Operand(lhs, ASR, 1));
......@@ -1585,7 +1496,7 @@ void GenericBinaryOpStub::HandleNonSmiBitwiseOp(MacroAssembler* masm,
__ ldr(r4, FieldMemOperand(rhs, HeapNumber::kMapOffset));
__ cmp(r4, heap_number_map);
__ b(ne, &slow);
GetInt32(masm, rhs, r2, r5, r4, &slow);
__ ConvertToInt32(rhs, r2, r5, r4, &slow);
__ jmp(&done_checking_rhs);
__ bind(&rhs_is_smi);
__ mov(r2, Operand(rhs, ASR, 1));
......@@ -2440,7 +2351,7 @@ void GenericUnaryOpStub::Generate(MacroAssembler* masm) {
__ b(ne, &slow);
// Convert the heap number is r0 to an untagged integer in r1.
GetInt32(masm, r0, r1, r2, r3, &slow);
__ ConvertToInt32(r0, r1, r2, r3, &slow);
// Do the bitwise operation (move negated) and check if the result
// fits in a smi.
......
src/arm/codegen-arm.cc
View file @ 76e3e2af
This diff is collapsed.
src/arm/macro-assembler-arm.cc
View file @ 76e3e2af
......@@ -25,6 +25,8 @@
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include <limits.h> // For LONG_MIN, LONG_MAX.
#include "v8.h"
#if defined(V8_TARGET_ARCH_ARM)
......@@ -1333,6 +1335,104 @@ void MacroAssembler::SmiToDoubleVFPRegister(Register smi,
}
// Tries to get a signed int32 out of a double precision floating point heap
// number. Rounds towards 0. Branch to 'not_int32' if the double is out of the
// 32bits signed integer range.
void MacroAssembler::ConvertToInt32(Register source,
Register dest,
Register scratch,
Register scratch2,
Label *not_int32) {
if (CpuFeatures::IsSupported(VFP3)) {
CpuFeatures::Scope scope(VFP3);
sub(scratch, source, Operand(kHeapObjectTag));
vldr(d0, scratch, HeapNumber::kValueOffset);
vcvt_s32_f64(s0, d0);
vmov(dest, s0);
// Signed vcvt instruction will saturate to the minimum (0x80000000) or
// maximun (0x7fffffff) signed 32bits integer when the double is out of
// range. When substracting one, the minimum signed integer becomes the
// maximun signed integer.
sub(scratch, dest, Operand(1));
cmp(scratch, Operand(LONG_MAX - 1));
// If equal then dest was LONG_MAX, if greater dest was LONG_MIN.
b(ge, not_int32);
} else {
// This code is faster 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
// 'not_int32' if the double isn't in the range -0x80000000.0 to
// 0x80000000.0 (excluding the endpoints).
Label right_exponent, done;
// Get exponent word.
ldr(scratch, FieldMemOperand(source, HeapNumber::kExponentOffset));
// Get exponent alone in scratch2.
Ubfx(scratch2,
scratch,
HeapNumber::kExponentShift,
HeapNumber::kExponentBits);
// Load dest with zero. We use this either for the final shift or
// for the answer.
mov(dest, Operand(0));
// 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). This is
// the exponent that we are fastest at and also the highest exponent we can
// handle here.
const uint32_t non_smi_exponent = HeapNumber::kExponentBias + 30;
// The non_smi_exponent, 0x41d, is too big for ARM's immediate field so we
// split it up to avoid a constant pool entry. You can't do that in general
// for cmp because of the overflow flag, but we know the exponent is in the
// range 0-2047 so there is no overflow.
int fudge_factor = 0x400;
sub(scratch2, scratch2, Operand(fudge_factor));
cmp(scratch2, Operand(non_smi_exponent - fudge_factor));
// If we have a match of the int32-but-not-Smi exponent then skip some
// logic.
b(eq, &right_exponent);
// If the exponent is higher than that then go to slow case. This catches
// numbers that don't fit in a signed int32, infinities and NaNs.
b(gt, not_int32);
// We know the exponent is smaller than 30 (biased). If it is less than
// 0 (biased) then the number is smaller in magnitude than 1.0 * 2^0, ie
// it rounds to zero.
const uint32_t zero_exponent = HeapNumber::kExponentBias + 0;
sub(scratch2, scratch2, Operand(zero_exponent - fudge_factor), SetCC);
// Dest already has a Smi zero.
b(lt, &done);
// We have an exponent between 0 and 30 in scratch2. Subtract from 30 to
// get how much to shift down.
rsb(dest, scratch2, Operand(30));
bind(&right_exponent);
// 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. For some exponents we don't
// actually need this because the bits get shifted out again, but
// it's probably slower to test than just to do it.
ldr(scratch, FieldMemOperand(source, HeapNumber::kMantissaOffset));
// Shift down 22 bits to get the last 10 bits.
orr(scratch, scratch2, Operand(scratch, LSR, 32 - shift_distance));
// Move down according to the exponent.
mov(dest, Operand(scratch, LSR, dest));
// Fix sign if sign bit was set.
rsb(dest, dest, Operand(0), LeaveCC, ne);
bind(&done);
}
}
void MacroAssembler::GetLeastBitsFromSmi(Register dst,
Register src,
int num_least_bits) {
......
src/arm/macro-assembler-arm.h
View file @ 76e3e2af
......@@ -504,6 +504,15 @@ class MacroAssembler: public Assembler {
Register scratch1,
SwVfpRegister scratch2);
// Convert the HeapNumber pointed to by source to a 32bits signed integer
// dest. If the HeapNumber does not fit into a 32bits signed integer branch
// to not_int32 label.
void ConvertToInt32(Register source,
Register dest,
Register scratch,
Register scratch2,
Label *not_int32);
// 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). Source and scratch can be the same in which case
......
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