Version 2.4.1
Added the ability for an embedding application to receive a callback when V8 allocates (V8::AddMemoryAllocationCallback) or deallocates (V8::RemoveMemoryAllocationCallback) from the OS.
Fixed several JSON bugs (including issue 855).
Fixed memory overrun crash bug triggered during V8's tick-based profiling.
Performance improvements on all platforms.
git-svn-id: http://v8.googlecode.com/svn/trunk@5412 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
diff --git a/src/arm/macro-assembler-arm.cc b/src/arm/macro-assembler-arm.cc
index 0b6e7b3..36a36be 100644
--- a/src/arm/macro-assembler-arm.cc
+++ b/src/arm/macro-assembler-arm.cc
@@ -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 @@
}
+// 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) {