diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp index 73320b556f825..be9843503298f 100644 --- a/llvm/lib/Analysis/ValueTracking.cpp +++ b/llvm/lib/Analysis/ValueTracking.cpp @@ -278,7 +278,16 @@ static bool isKnownNonZero(const Value *V, const APInt &DemandedElts, bool llvm::isKnownNonNegative(const Value *V, const SimplifyQuery &SQ, unsigned Depth) { - return computeKnownBits(V, SQ, Depth).isNonNegative(); + if (computeKnownBits(V, SQ, Depth).isNonNegative()) + return true; + + Value *X, *Y; + if (match(V, m_NSWSub(m_Value(X), m_Value(Y)))) + if (std::optional result = + isImpliedByDomCondition(ICmpInst::ICMP_SLE, Y, X, SQ.CxtI, SQ.DL)) + return *result; + + return false; } bool llvm::isKnownPositive(const Value *V, const SimplifyQuery &SQ, diff --git a/llvm/test/Transforms/InstCombine/sub-after-sle-is-non-negative.ll b/llvm/test/Transforms/InstCombine/sub-after-sle-is-non-negative.ll new file mode 100644 index 0000000000000..279a6de4125ed --- /dev/null +++ b/llvm/test/Transforms/InstCombine/sub-after-sle-is-non-negative.ll @@ -0,0 +1,53 @@ +; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5 +; RUN: opt < %s -passes=instcombine -S | FileCheck %s +define void @test_as_arg(i8 %a, i8 %b) { +; CHECK-LABEL: define void @test_as_arg( +; CHECK-SAME: i8 [[A:%.*]], i8 [[B:%.*]]) { +; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i8 [[A]], [[B]] +; CHECK-NEXT: br i1 [[CMP]], label %[[COND_END:.*]], label %[[COND_FALSE:.*]] +; CHECK: [[COND_FALSE]]: +; CHECK-NEXT: [[SUB:%.*]] = sub nsw i8 [[B]], [[A]] +; CHECK-NEXT: [[CONV:%.*]] = zext nneg i8 [[SUB]] to i16 +; CHECK-NEXT: call void @subroutine(i16 [[CONV]]) +; CHECK-NEXT: br label %[[COND_END]] +; CHECK: [[COND_END]]: +; CHECK-NEXT: ret void +; + %cmp = icmp sgt i8 %a, %b + br i1 %cmp, label %cond.end, label %cond.false + +cond.false: + %sub = sub nsw i8 %b, %a + %conv = sext i8 %sub to i16 + call void @subroutine(i16 %conv) + br label %cond.end + +cond.end: + ret void +} + +declare void @subroutine(i16) + +define i16 @test_as_retval(i8 %a, i8 %b) { +; CHECK-LABEL: define i16 @test_as_retval( +; CHECK-SAME: i8 [[A:%.*]], i8 [[B:%.*]]) { +; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i8 [[A]], [[B]] +; CHECK-NEXT: br i1 [[CMP]], label %[[COND_TRUE:.*]], label %[[COND_FALSE:.*]] +; CHECK: [[COND_TRUE]]: +; CHECK-NEXT: ret i16 0 +; CHECK: [[COND_FALSE]]: +; CHECK-NEXT: [[SUB:%.*]] = sub nsw i8 [[B]], [[A]] +; CHECK-NEXT: [[CONV:%.*]] = zext nneg i8 [[SUB]] to i16 +; CHECK-NEXT: ret i16 [[CONV]] +; + %cmp = icmp sgt i8 %a, %b + br i1 %cmp, label %cond.true, label %cond.false + +cond.true: + ret i16 0 + +cond.false: + %sub = sub nsw i8 %b, %a + %conv = sext i8 %sub to i16 + ret i16 %conv +} pFad - Phonifier reborn

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