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[PatternMatch] Match commuted patterns in Signum_match #121911

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Merged
merged 2 commits into from
Jan 7, 2025
Merged

[PatternMatch] Match commuted patterns in Signum_match #121911

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aa5e48a
[InstCombine] Add pre-commit tests. NFC.
dtcxzyw Jan 7, 2025
f578320
[PatternMatch] Match commuted patterns in `Signum_match`
dtcxzyw Jan 7, 2025
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10 changes: 5 additions & 5 deletions llvm/include/llvm/IR/PatternMatch.h
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Original file line number Diff line number Diff line change
Expand Up @@ -2870,7 +2870,7 @@ template <typename Opnd_t> struct Signum_match {
return false;

unsigned ShiftWidth = TypeSize - 1;
Value *OpL = nullptr, *OpR = nullptr;
Value *Op;

// This is the representation of signum we match:
//
Expand All @@ -2882,11 +2882,11 @@ template <typename Opnd_t> struct Signum_match {
//
// for i1 values.

auto LHS = m_AShr(m_Value(OpL), m_SpecificInt(ShiftWidth));
auto RHS = m_LShr(m_Neg(m_Value(OpR)), m_SpecificInt(ShiftWidth));
auto Signum = m_Or(LHS, RHS);
auto LHS = m_AShr(m_Value(Op), m_SpecificInt(ShiftWidth));
auto RHS = m_LShr(m_Neg(m_Deferred(Op)), m_SpecificInt(ShiftWidth));
auto Signum = m_c_Or(LHS, RHS);

return Signum.match(V) && OpL == OpR && Val.match(OpL);
return Signum.match(V) && Val.match(Op);
}
};

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13 changes: 13 additions & 0 deletions llvm/test/Transforms/InstCombine/compare-signs.ll
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Expand Up @@ -152,6 +152,19 @@ define i1 @test4a(i32 %a) {
ret i1 %c
}

define i1 @test4a_commuted(i32 %a) {
; CHECK-LABEL: @test4a_commuted(
; CHECK-NEXT: [[C:%.*]] = icmp slt i32 [[SIGNUM:%.*]], 1
; CHECK-NEXT: ret i1 [[C]]
;
%l = ashr i32 %a, 31
%na = sub i32 0, %a
%r = lshr i32 %na, 31
%signum = or i32 %r, %l
%c = icmp slt i32 %signum, 1
ret i1 %c
}

define <2 x i1> @test4a_vec(<2 x i32> %a) {
; CHECK-LABEL: @test4a_vec(
; CHECK-NEXT: [[C:%.*]] = icmp slt <2 x i32> [[A:%.*]], splat (i32 1)
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