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[InstCombine] Fold icmp spred (X *nsw Z), (Y *nsw Z) -> icmp pred Z, 0 if scmp(X, Y) is known #118726

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Merged
merged 2 commits into from
Dec 5, 2024
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[InstCombine] Fold icmp spred (X *nsw Z), (Y *nsw Z) -> icmp pred Z, 0 if scmp(X, Y) is known #118726

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adde6a8
[InstCombine] Add pre-commit tests. NFC.
dtcxzyw Dec 5, 2024
cb460c2
[InstCombine] Fold `icmp spred (X *nsw Z), (Y *nsw Z) i-> icmp pred Z…
dtcxzyw Dec 5, 2024
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9 changes: 9 additions & 0 deletions llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -5337,6 +5337,15 @@ Instruction *InstCombinerImpl::foldICmpBinOp(ICmpInst &I,
return new ICmpInst(Pred, X, Y);
if (ZKnown.isNegative())
return new ICmpInst(ICmpInst::getSwappedPredicate(Pred), X, Y);
Value *LessThan = simplifyICmpInst(ICmpInst::ICMP_SLT, X, Y,
SQ.getWithInstruction(&I));
if (LessThan && match(LessThan, m_One()))
return new ICmpInst(ICmpInst::getSwappedPredicate(Pred), Z,
Constant::getNullValue(Z->getType()));
Value *GreaterThan = simplifyICmpInst(ICmpInst::ICMP_SGT, X, Y,
SQ.getWithInstruction(&I));
if (GreaterThan && match(GreaterThan, m_One()))
return new ICmpInst(Pred, Z, Constant::getNullValue(Z->getType()));
}
} else {
bool NonZero;
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104 changes: 104 additions & 0 deletions llvm/test/Transforms/InstCombine/icmp-mul.ll
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Expand Up @@ -1464,3 +1464,107 @@ entry:
%cmp = icmp slt i8 %mul1, %mul2
ret i1 %cmp
}

define i1 @test_icmp_slt_mul_known_sgt(i64 %x, i64 %z) {
; CHECK-LABEL: @test_icmp_slt_mul_known_sgt(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i64 [[Z:%.*]], 0
; CHECK-NEXT: ret i1 [[CMP]]
;
entry:
%y = add nsw i64 %x, 1
%mul1 = mul nsw i64 %x, %z
%mul2 = mul nsw i64 %y, %z
%cmp = icmp slt i64 %mul1, %mul2
ret i1 %cmp
}

define i1 @test_icmp_sle_mul_known_sgt(i64 %x, i64 %z) {
; CHECK-LABEL: @test_icmp_sle_mul_known_sgt(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i64 [[Z:%.*]], -1
; CHECK-NEXT: ret i1 [[CMP]]
;
entry:
%y = add nsw i64 %x, 1
%mul1 = mul nsw i64 %x, %z
%mul2 = mul nsw i64 %y, %z
%cmp = icmp sle i64 %mul1, %mul2
ret i1 %cmp
}

define i1 @test_icmp_mul_known_slt(i64 %x, i64 %z) {
; CHECK-LABEL: @test_icmp_mul_known_slt(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i64 [[Z:%.*]], 0
; CHECK-NEXT: ret i1 [[CMP]]
;
entry:
%y = add nsw i64 %x, 1
%mul1 = mul nsw i64 %x, %z
%mul2 = mul nsw i64 %y, %z
%cmp = icmp slt i64 %mul2, %mul1
ret i1 %cmp
}

define i1 @test_icmp_slt_mul_known_sgt_commuted1(i64 %x, i64 %z) {
; CHECK-LABEL: @test_icmp_slt_mul_known_sgt_commuted1(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i64 [[Z:%.*]], 0
; CHECK-NEXT: ret i1 [[CMP]]
;
entry:
%y = add nsw i64 %x, 1
%mul1 = mul nsw i64 %z, %x
%mul2 = mul nsw i64 %y, %z
%cmp = icmp slt i64 %mul1, %mul2
ret i1 %cmp
}

define i1 @test_icmp_slt_mul_known_sgt_commuted2(i64 %x, i64 %z) {
; CHECK-LABEL: @test_icmp_slt_mul_known_sgt_commuted2(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i64 [[Z:%.*]], 0
; CHECK-NEXT: ret i1 [[CMP]]
;
entry:
%y = add nsw i64 %x, 1
%mul1 = mul nsw i64 %x, %z
%mul2 = mul nsw i64 %z, %y
%cmp = icmp slt i64 %mul1, %mul2
ret i1 %cmp
}

define i1 @test_icmp_slt_mul_unknown(i64 %x, i64 %z) {
; CHECK-LABEL: @test_icmp_slt_mul_unknown(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[Y:%.*]] = add i64 [[X:%.*]], 1
; CHECK-NEXT: [[MUL1:%.*]] = mul nsw i64 [[X]], [[Z:%.*]]
; CHECK-NEXT: [[MUL2:%.*]] = mul nsw i64 [[Z]], [[Y]]
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i64 [[MUL1]], [[MUL2]]
; CHECK-NEXT: ret i1 [[CMP]]
;
entry:
%y = add i64 %x, 1
%mul1 = mul nsw i64 %x, %z
%mul2 = mul nsw i64 %z, %y
%cmp = icmp slt i64 %mul1, %mul2
ret i1 %cmp
}

define i1 @test_icmp_slt_mul_no_nsw(i64 %x, i64 %z) {
; CHECK-LABEL: @test_icmp_slt_mul_no_nsw(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[Y:%.*]] = add nsw i64 [[X:%.*]], 1
; CHECK-NEXT: [[MUL1:%.*]] = mul i64 [[X]], [[Z:%.*]]
; CHECK-NEXT: [[MUL2:%.*]] = mul nsw i64 [[Z]], [[Y]]
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i64 [[MUL1]], [[MUL2]]
; CHECK-NEXT: ret i1 [[CMP]]
;
entry:
%y = add nsw i64 %x, 1
%mul1 = mul i64 %x, %z
%mul2 = mul nsw i64 %z, %y
%cmp = icmp slt i64 %mul1, %mul2
ret i1 %cmp
}
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