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Arm64: Rewrite Set/GetRoundingMode

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I went auditing for places to use cset and what I found was hot garbage.

Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
This commit is contained in:
Alyssa Rosenzweig committed 2023-09-24 19:52:35 -04:00
1 parent c5fc03dac4
commit 8798e0cba0
1 file changed
+16 -31
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FEXCore/Source/Interface/Core/JIT/Arm64/MiscOps.cpp
+16 -31
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@@ -83,47 +83,32 @@ DEF_OP(Break) {
DEF_OP(GetRoundingMode) {
auto Dst = GetReg(Node);
mrs(Dst, ARMEmitter::SystemRegister::FPCR);
lsr(ARMEmitter::Size::i64Bit, Dst, Dst, 22);
ubfx(ARMEmitter::Size::i64Bit, Dst, Dst, 22, 3);
// FTZ is already in the correct location
// Rounding mode is different
and_(ARMEmitter::Size::i64Bit, TMP1, Dst, 0b11);
//
// Need to remap rounding mode from order nearest, pos inf, neg inf, toward
// zero. Just swapping 01 and 10. That's a bitfield reverse. Round mode is in
// bottom two bits. After reversing as a 32-bit operation, it'll be in [31:30]
// and ripe for reinsertion back at 0.
static_assert(IR::ROUND_MODE_NEAREST == 0);
static_assert(IR::ROUND_MODE_NEGATIVE_INFINITY == 1);
static_assert(IR::ROUND_MODE_POSITIVE_INFINITY == 2);
static_assert(IR::ROUND_MODE_TOWARDS_ZERO == 3);
cmp(ARMEmitter::Size::i64Bit, TMP1, 1);
LoadConstant(ARMEmitter::Size::i64Bit, TMP3, IR::ROUND_MODE_POSITIVE_INFINITY);
csel(ARMEmitter::Size::i64Bit, TMP2, TMP3, ARMEmitter::Reg::zr, ARMEmitter::Condition::CC_EQ);
cmp(ARMEmitter::Size::i64Bit, TMP1, 2);
LoadConstant(ARMEmitter::Size::i64Bit, TMP3, IR::ROUND_MODE_NEGATIVE_INFINITY);
csel(ARMEmitter::Size::i64Bit, TMP2, TMP3, TMP2, ARMEmitter::Condition::CC_EQ);
cmp(ARMEmitter::Size::i64Bit, TMP1, 3);
LoadConstant(ARMEmitter::Size::i64Bit, TMP3, IR::ROUND_MODE_TOWARDS_ZERO);
csel(ARMEmitter::Size::i64Bit, TMP2, TMP3, TMP2, ARMEmitter::Condition::CC_EQ);
orr(ARMEmitter::Size::i64Bit, Dst, Dst, TMP2.R());
bfi(ARMEmitter::Size::i64Bit, Dst, TMP2, 0, 2);
rbit(ARMEmitter::Size::i32Bit, TMP1, Dst);
bfi(ARMEmitter::Size::i64Bit, Dst, TMP1, 30, 2);
}
DEF_OP(SetRoundingMode) {
auto Op = IROp->C<IR::IROp_SetRoundingMode>();
auto Src = GetReg(Op->RoundMode.ID());
// Setup the rounding flags correctly
and_(ARMEmitter::Size::i64Bit, TMP1, Src, 0b11);
cmp(ARMEmitter::Size::i64Bit, TMP1, IR::ROUND_MODE_POSITIVE_INFINITY);
LoadConstant(ARMEmitter::Size::i64Bit, TMP3, 1);
csel(ARMEmitter::Size::i64Bit, TMP2, TMP3, ARMEmitter::Reg::zr, ARMEmitter::Condition::CC_EQ);
cmp(ARMEmitter::Size::i64Bit, TMP1, IR::ROUND_MODE_NEGATIVE_INFINITY);
LoadConstant(ARMEmitter::Size::i64Bit, TMP3, 2);
csel(ARMEmitter::Size::i64Bit, TMP2, TMP3, TMP2, ARMEmitter::Condition::CC_EQ);
cmp(ARMEmitter::Size::i64Bit, TMP1, IR::ROUND_MODE_TOWARDS_ZERO);
LoadConstant(ARMEmitter::Size::i64Bit, TMP3, 3);
csel(ARMEmitter::Size::i64Bit, TMP2, TMP3, TMP2, ARMEmitter::Condition::CC_EQ);
// As above, setup the rounding flags in [31:30]
rbit(ARMEmitter::Size::i32Bit, TMP2, Src);
// and extract
lsr(ARMEmitter::Size::i32Bit, TMP2, TMP2, 30);
mrs(TMP1, ARMEmitter::SystemRegister::FPCR);