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emit_x64: Optimize code emitted by EmitGetCpsr

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This commit is contained in:
MerryMage 2017-12-12 14:19:48 +00:00
parent 4393473d06
commit 5c6fcf378f
1 changed files with 29 additions and 3 deletions
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26
src/backend_x64/emit_x64.cpp
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@ -196,10 +196,36 @@ static u32 GetCpsrImpl(JitState* jit_state) {
}
void EmitX64::EmitGetCpsr(RegAlloc& reg_alloc, IR::Block&, IR::Inst* inst) {
if (code->DoesCpuSupport(Xbyak::util::Cpu::tBMI2)) {
Xbyak::Reg32 result = reg_alloc.ScratchGpr().cvt32();
Xbyak::Reg32 b = reg_alloc.ScratchGpr().cvt32();
Xbyak::Reg32 c = reg_alloc.ScratchGpr().cvt32();
code->mov(c, dword[r15 + offsetof(JitState, CPSR_ge)]);
// Here we observe that CPSR_q and CPSR_nzcv are right next to each other in memory,
// so we load them both at the same time with one 64-bit read. This allows us to
// extract all of their bits together at once with one pext.
code->mov(result.cvt64(), qword[r15 + offsetof(JitState, CPSR_q)]);
code->mov(b.cvt64(), 0xF000000000000001ull);
code->pext(result.cvt64(), result.cvt64(), b.cvt64());
code->mov(b, 0x80808080);
code->pext(c.cvt64(), c.cvt64(), b.cvt64());
code->shl(result, 27);
code->shl(c, 16);
code->or_(result, c);
code->mov(b, 0x00000220);
code->mov(c, dword[r15 + offsetof(JitState, CPSR_et)]);
code->pdep(c.cvt64(), c.cvt64(), b.cvt64());
code->or_(result, dword[r15 + offsetof(JitState, CPSR_jaifm)]);
code->or_(result, c);
reg_alloc.DefineValue(inst, result);
} else {
reg_alloc.HostCall(inst);
code->mov(code->ABI_PARAM1, code->r15);
code->CallFunction(&GetCpsrImpl);
}
}
static void SetCpsrImpl(u32 value, JitState* jit_state) {
jit_state->SetCpsr(value);