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Unified Diff: src/arm/macro-assembler-arm.cc

Issue 532003004: Generalized division via multiplication. (Closed) Base URL: https://v8.googlecode.com/svn/branches/bleeding_edge
Patch Set: Rebased Created 6 years, 3 months ago
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Index: src/arm/macro-assembler-arm.cc
diff --git a/src/arm/macro-assembler-arm.cc b/src/arm/macro-assembler-arm.cc
index 619c9446009e54f4323b5ba3af53eb671f66fc33..d16d5b63561f987a8c3c7a9f7f328430ddba4dba 100644
--- a/src/arm/macro-assembler-arm.cc
+++ b/src/arm/macro-assembler-arm.cc
@@ -9,6 +9,7 @@
#if V8_TARGET_ARCH_ARM
#include "src/base/bits.h"
+#include "src/base/division-by-constant.h"
#include "src/bootstrapper.h"
#include "src/codegen.h"
#include "src/cpu-profiler.h"
@@ -4093,16 +4094,18 @@ void MacroAssembler::TruncatingDiv(Register result,
DCHECK(!dividend.is(result));
DCHECK(!dividend.is(ip));
DCHECK(!result.is(ip));
- MultiplierAndShift ms(divisor);
- mov(ip, Operand(ms.multiplier()));
+ base::MagicNumbersForDivision<uint32_t> mag =
+ base::SignedDivisionByConstant(static_cast<uint32_t>(divisor));
+ mov(ip, Operand(mag.multiplier));
smull(ip, result, dividend, ip);
- if (divisor > 0 && ms.multiplier() < 0) {
+ bool neg = (mag.multiplier & (static_cast<uint32_t>(1) << 31)) != 0;
+ if (divisor > 0 && neg) {
add(result, result, Operand(dividend));
}
- if (divisor < 0 && ms.multiplier() > 0) {
+ if (divisor < 0 && !neg && mag.multiplier > 0) {
sub(result, result, Operand(dividend));
}
- if (ms.shift() > 0) mov(result, Operand(result, ASR, ms.shift()));
+ if (mag.shift > 0) mov(result, Operand(result, ASR, mag.shift));
add(result, result, Operand(dividend, LSR, 31));
}
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