From af4e59949cc4cc895be76a441a2a867189ee0f55 Mon Sep 17 00:00:00 2001 From: Sanjay Patel Date: Mon, 2 Dec 2019 12:10:05 -0500 Subject: [PATCH] [InstCombine] fix undef propagation for vector urem transform (PR44186) As described here: https://bugs.llvm.org/show_bug.cgi?id=44186 The match() code safely allows undef values, but we can't safely propagate a vector constant that contains an undef to the new compare instruction. --- llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp | 6 ++++-- llvm/test/Transforms/InstCombine/vector-urem.ll | 2 +- 2 files changed, 5 insertions(+), 3 deletions(-) diff --git a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp index 0b9128a..f7b39d9 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp @@ -1368,8 +1368,10 @@ Instruction *InstCombiner::visitURem(BinaryOperator &I) { } // 1 urem X -> zext(X != 1) - if (match(Op0, m_One())) - return CastInst::CreateZExtOrBitCast(Builder.CreateICmpNE(Op1, Op0), Ty); + if (match(Op0, m_One())) { + Value *Cmp = Builder.CreateICmpNE(Op1, ConstantInt::get(Ty, 1)); + return CastInst::CreateZExtOrBitCast(Cmp, Ty); + } // X urem C -> X < C ? X : X - C, where C >= signbit. if (match(Op1, m_Negative())) { diff --git a/llvm/test/Transforms/InstCombine/vector-urem.ll b/llvm/test/Transforms/InstCombine/vector-urem.ll index 113451f..c9b79b2 100644 --- a/llvm/test/Transforms/InstCombine/vector-urem.ll +++ b/llvm/test/Transforms/InstCombine/vector-urem.ll @@ -39,7 +39,7 @@ define <4 x i32> @test_v4i32_one(<4 x i32> %a0) { define <4 x i32> @test_v4i32_one_undef(<4 x i32> %a0) { ; CHECK-LABEL: @test_v4i32_one_undef( -; CHECK-NEXT: [[TMP1:%.*]] = icmp ne <4 x i32> [[A0:%.*]], +; CHECK-NEXT: [[TMP1:%.*]] = icmp ne <4 x i32> [[A0:%.*]], ; CHECK-NEXT: [[TMP2:%.*]] = zext <4 x i1> [[TMP1]] to <4 x i32> ; CHECK-NEXT: ret <4 x i32> [[TMP2]] ; -- 2.7.4