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Bug 1811809: Use non-signalling Neg instruction for MacroAssembler::neg32, neg64, and negPtr. r=jandem

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The condition flags needed to be set before we had `branchNeg32`, but now that
`branchNeg32` is present, the normal `neg32` operation can use `Neg` instead
of `Negs`.

Differential Revision: https://phabricator.services.mozilla.com/D167525
This commit is contained in:
André Bargull 2023-01-27 10:40:31 +00:00
parent 5295cbaefd
commit 2c66fa8c20
3 changed files with 12 additions and 3 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

5
js/src/jit/MacroAssembler.h
View file

@ -1062,6 +1062,11 @@ class MacroAssembler : public MacroAssemblerSpecific {
// ===============================================================
// Arithmetic functions
// Condition flags aren't guaranteed to be set by these functions, for example
// x86 will always set condition flags, but ARM64 won't do it unless
// explicitly requested. Instead use branch(Add|Sub|Mul|Neg) to test for
// condition flags after performing arithmetic operations.
inline void add32(Register src, Register dest) PER_SHARED_ARCH;
inline void add32(Imm32 imm, Register dest) PER_SHARED_ARCH;
inline void add32(Imm32 imm, const Address& dest) PER_SHARED_ARCH;

6
js/src/jit/arm64/MacroAssembler-arm64-inl.h
View file

@ -560,13 +560,13 @@ void MacroAssembler::inc64(AbsoluteAddress dest) {
}
void MacroAssembler::neg32(Register reg) {
Negs(ARMRegister(reg, 32), Operand(ARMRegister(reg, 32)));
Neg(ARMRegister(reg, 32), Operand(ARMRegister(reg, 32)));
}
void MacroAssembler::neg64(Register64 reg) { negPtr(reg.reg); }
void MacroAssembler::negPtr(Register reg) {
Negs(ARMRegister(reg, 64), Operand(ARMRegister(reg, 64)));
Neg(ARMRegister(reg, 64), Operand(ARMRegister(reg, 64)));
}
void MacroAssembler::negateFloat(FloatRegister reg) {
@ -1475,7 +1475,7 @@ void MacroAssembler::branchRshift32(Condition cond, T src, Register dest,
void MacroAssembler::branchNeg32(Condition cond, Register reg, Label* label) {
MOZ_ASSERT(cond == Overflow);
neg32(reg);
negs32(reg);
B(label, cond);
}

4
js/src/jit/arm64/MacroAssembler-arm64.h
View file

@ -1274,6 +1274,10 @@ class MacroAssemblerCompat : public vixl::MacroAssembler {
Operand(ARMRegister(src, 64)));
}
void negs32(Register reg) {
Negs(ARMRegister(reg, 32), Operand(ARMRegister(reg, 32)));
}
void ret() {
pop(lr);
abiret();