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[GlobalIsel] Combine select to integer min max more #92570

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Merged
merged 2 commits into from
May 18, 2024
Merged

[GlobalIsel] Combine select to integer min max more #92570

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[GlobalIsel] Combine select to integer min max more
tschuett May 17, 2024
566ee94
early exit
tschuett May 17, 2024
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2 changes: 1 addition & 1 deletion llvm/include/llvm/Target/GlobalISel/Combine.td
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Original file line number Diff line number Diff line change
Expand Up @@ -1309,7 +1309,7 @@ def select_to_minmax: GICombineRule<

def select_to_iminmax: GICombineRule<
(defs root:$root, build_fn_matchinfo:$info),
(match (G_ICMP $tst, $tst1, $x, $y),
(match (G_ICMP $tst, $tst1, $a, $b),
(G_SELECT $root, $tst, $x, $y),
[{ return Helper.matchSelectIMinMax(${root}, ${info}); }]),
(apply [{ Helper.applyBuildFnMO(${root}, ${info}); }])>;
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13 changes: 10 additions & 3 deletions llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
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Expand Up @@ -6772,13 +6772,20 @@ bool CombinerHelper::matchSelectIMinMax(const MachineOperand &MO,
if (CmpInst::isEquality(Pred))
return false;

[[maybe_unused]] Register CmpLHS = Cmp->getLHSReg();
[[maybe_unused]] Register CmpRHS = Cmp->getRHSReg();
Register CmpLHS = Cmp->getLHSReg();
Register CmpRHS = Cmp->getRHSReg();

// We can swap CmpLHS and CmpRHS for higher hitrate.
if (True == CmpRHS && False == CmpLHS) {
std::swap(CmpLHS, CmpRHS);
Pred = CmpInst::getSwappedPredicate(Pred);
}

// (icmp X, Y) ? X : Y -> integer minmax.
// see matchSelectPattern in ValueTracking.
// Legality between G_SELECT and integer minmax can differ.
assert(True == CmpLHS && False == CmpRHS && "unexpected MIR pattern");
if (True != CmpLHS || False != CmpRHS)
return false;

switch (Pred) {
case ICmpInst::ICMP_UGT:
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3 changes: 1 addition & 2 deletions llvm/test/CodeGen/AArch64/GlobalISel/combine-select.mir
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Expand Up @@ -911,8 +911,7 @@ body: |
; CHECK-NEXT: %f1:_(s32) = G_TRUNC [[COPY1]](s64)
; CHECK-NEXT: %t:_(<4 x s32>) = G_BUILD_VECTOR %t1(s32), %t1(s32), %t1(s32), %t1(s32)
; CHECK-NEXT: %f:_(<4 x s32>) = G_BUILD_VECTOR %f1(s32), %f1(s32), %f1(s32), %f1(s32)
; CHECK-NEXT: %c:_(<4 x s32>) = G_ICMP intpred(sle), %f(<4 x s32>), %t
; CHECK-NEXT: %sel:_(<4 x s32>) = exact G_SELECT %c(<4 x s32>), %t, %f
; CHECK-NEXT: %sel:_(<4 x s32>) = G_SMAX %t, %f
; CHECK-NEXT: $q0 = COPY %sel(<4 x s32>)
%0:_(s64) = COPY $x0
%1:_(s64) = COPY $x1
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