[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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…, 0` if `scmp(X, Y)` is known
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@llvm/pr-subscribers-llvm-transforms Author: Yingwei Zheng (dtcxzyw) ChangesAlive2: https://alive2.llvm.org/ce/z/F2D0GE Full diff: https://github.com/llvm/llvm-project/pull/118726.diff 2 Files Affected:
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index fed21db393ed22..e31af8104e147c 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -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;
diff --git a/llvm/test/Transforms/InstCombine/icmp-mul.ll b/llvm/test/Transforms/InstCombine/icmp-mul.ll
index c9f9b6d809e8a5..49e1e11fe6c36f 100644
--- a/llvm/test/Transforms/InstCombine/icmp-mul.ll
+++ b/llvm/test/Transforms/InstCombine/icmp-mul.ll
@@ -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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This was referenced Dec 5, 2024
Collaborator
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/30/builds/11628 Here is the relevant piece of the build log for the reference |
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Alive2: https://alive2.llvm.org/ce/z/F2D0GE