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JitArm64: Use LogicalImm in boolX #12060

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Aug 13, 2023
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JitArm64: Use LogicalImm in boolX #12060

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99 changes: 76 additions & 23 deletions Source/Core/Core/PowerPC/JitArm64/JitArm64_Integer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -323,8 +323,10 @@ void JitArm64::boolX(UGeckoInstruction inst)
PanicAlertFmt("WTF!");
}
}
else if ((gpr.IsImm(s) && (gpr.GetImm(s) == 0 || gpr.GetImm(s) == 0xFFFFFFFF)) ||
(gpr.IsImm(b) && (gpr.GetImm(b) == 0 || gpr.GetImm(b) == 0xFFFFFFFF)))
else if ((gpr.IsImm(s) &&
(gpr.GetImm(s) == 0 || gpr.GetImm(s) == 0xFFFFFFFF || LogicalImm(gpr.GetImm(s), 32))) ||
(gpr.IsImm(b) &&
(gpr.GetImm(b) == 0 || gpr.GetImm(b) == 0xFFFFFFFF || LogicalImm(gpr.GetImm(b), 32))))
{
int i, j;
if (gpr.IsImm(s))
Expand All @@ -337,7 +339,6 @@ void JitArm64::boolX(UGeckoInstruction inst)
i = b;
j = s;
}
bool is_zero = gpr.GetImm(i) == 0;

bool complement_b = (inst.SUBOP10 == 60 /* andcx */) || (inst.SUBOP10 == 412 /* orcx */);
const bool final_not = (inst.SUBOP10 == 476 /* nandx */) || (inst.SUBOP10 == 124 /* norx */);
Expand All @@ -347,23 +348,39 @@ void JitArm64::boolX(UGeckoInstruction inst)
(inst.SUBOP10 == 124 /* norx */);
const bool is_xor = (inst.SUBOP10 == 316 /* xorx */) || (inst.SUBOP10 == 284 /* eqvx */);

u32 imm = gpr.GetImm(i);
if ((complement_b && i == b) || (inst.SUBOP10 == 284 /* eqvx */))
{
is_zero = !is_zero;
imm = ~imm;
complement_b = false;
}

const bool is_zero = imm == 0;
const bool is_ones = imm == 0xFFFFFFFF;
// If imm can be represented as LogicalImm, so can ~imm.
const auto log_imm = LogicalImm(imm, 32);

if (is_xor)
{
if (!is_zero)
if (is_zero)
{
gpr.BindToRegister(a, a == j);
MVN(gpr.R(a), gpr.R(j));
if (a != j)
{
gpr.BindToRegister(a, false);
MOV(gpr.R(a), gpr.R(j));
}
}
else if (a != j)
else
{
gpr.BindToRegister(a, false);
MOV(gpr.R(a), gpr.R(j));
gpr.BindToRegister(a, a == j);
if (is_ones)
{
MVN(gpr.R(a), gpr.R(j));
}
else
{
EOR(gpr.R(a), gpr.R(j), log_imm);
}
}
if (inst.Rc)
ComputeRC0(gpr.R(a));
Expand All @@ -376,45 +393,81 @@ void JitArm64::boolX(UGeckoInstruction inst)
if (inst.Rc)
ComputeRC0(gpr.GetImm(a));
}
else if (final_not || complement_b)
else if (is_ones)
{
gpr.BindToRegister(a, a == j);
MVN(gpr.R(a), gpr.R(j));
if (final_not || complement_b)
{
gpr.BindToRegister(a, a == j);
MVN(gpr.R(a), gpr.R(j));
}
else if (a != j)
{
gpr.BindToRegister(a, false);
MOV(gpr.R(a), gpr.R(j));
}
if (inst.Rc)
ComputeRC0(gpr.R(a));
}
else
{
if (a != j)
if (!complement_b)
{
gpr.BindToRegister(a, false);
MOV(gpr.R(a), gpr.R(j));
gpr.BindToRegister(a, a == j);
AND(gpr.R(a), gpr.R(j), log_imm);
if (final_not)
MVN(gpr.R(a), gpr.R(a));
Comment on lines +416 to +418
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In the final_not case, we could make use of de Morgan's laws and turn ~(s & b) into ~s | ~b. Since inverting the immediate has no runtime cost, this would let us replace the AND+MVN with ORN. But inverting the immediate after we already have log_imm seems like effort... So I'll leave it up to you if you want to try implementing this in this PR or not.

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Sorry, forgot about this for a while.

Not a bad idea. You can even use this approach for any immediate, not just those that can be expressed as LogicalImm. But you still need to materialize the immediate somehow and that might take more than one MOV instruction, in which case using LogicalImm might still be preferable...

I should also note that I haven't seen a single game use nand with immediates. And the only game that I've seen use nor is Zelda Master Quest.

So given the complexity and how uncommon these instruction patterns are, I think it would be better to leave this for a follow-up PR for now, if that's alright with you.

}
else
{
// No shorter instruction sequence is possible. Just materialize the
// immediate in a register as usual, so subsequent uses can leech off
// of it.
gpr.BindToRegister(a, (a == i) || (a == j));
BIC(gpr.R(a), gpr.R(i), gpr.R(j));
}
if (inst.Rc)
ComputeRC0(gpr.R(a));
}
}
else if (is_or)
{
if (!is_zero)
if (is_ones)
{
gpr.SetImmediate(a, final_not ? 0 : 0xFFFFFFFF);
if (inst.Rc)
ComputeRC0(gpr.GetImm(a));
}
else if (final_not || complement_b)
else if (is_zero)
{
gpr.BindToRegister(a, a == j);
MVN(gpr.R(a), gpr.R(j));
if (final_not || complement_b)
{
gpr.BindToRegister(a, a == j);
MVN(gpr.R(a), gpr.R(j));
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}
else if (a != j)
{
gpr.BindToRegister(a, false);
MOV(gpr.R(a), gpr.R(j));
}
if (inst.Rc)
ComputeRC0(gpr.R(a));
}
else
{
if (a != j)
if (!complement_b)
{
gpr.BindToRegister(a, false);
MOV(gpr.R(a), gpr.R(j));
gpr.BindToRegister(a, a == j);
ORR(gpr.R(a), gpr.R(j), log_imm);
if (final_not)
MVN(gpr.R(a), gpr.R(a));
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Same here regarding de Morgan's laws.

}
else
{
// No shorter instruction sequence is possible. Just materialize the
// immediate in a register as usual, so subsequent uses can leech off
// of it.
gpr.BindToRegister(a, (a == i) || (a == j));
ORN(gpr.R(a), gpr.R(i), gpr.R(j));
}
if (inst.Rc)
ComputeRC0(gpr.R(a));
Expand Down