From ee2b7a4530736d311fb3e2eae551e0acdb919354 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Sun, 13 Jan 2008 20:59:02 +0000 Subject: [PATCH] Fix PR1907, a nasty miscompilation because instcombine didn't realize that ne & sgt was a signed comparison (it was only looking at whether the left compare was signed). git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@45937 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/Scalar/InstructionCombining.cpp | 10 ++++++++-- test/Transforms/InstCombine/2008-01-13-AndCmpCmp.ll | 9 +++++++++ 2 files changed, 17 insertions(+), 2 deletions(-) create mode 100644 test/Transforms/InstCombine/2008-01-13-AndCmpCmp.ll diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp index ea53aec76cb..9465a31d29d 100644 --- a/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/lib/Transforms/Scalar/InstructionCombining.cpp @@ -3495,8 +3495,14 @@ Instruction *InstCombiner::visitAnd(BinaryOperator &I) { ICmpInst::isSignedPredicate(LHSCC) == ICmpInst::isSignedPredicate(RHSCC))) { // Ensure that the larger constant is on the RHS. - ICmpInst::Predicate GT = ICmpInst::isSignedPredicate(LHSCC) ? - ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; + ICmpInst::Predicate GT; + if (ICmpInst::isSignedPredicate(LHSCC) || + (ICmpInst::isEquality(LHSCC) && + ICmpInst::isSignedPredicate(RHSCC))) + GT = ICmpInst::ICMP_SGT; + else + GT = ICmpInst::ICMP_UGT; + Constant *Cmp = ConstantExpr::getICmp(GT, LHSCst, RHSCst); ICmpInst *LHS = cast(Op0); if (cast(Cmp)->getZExtValue()) { diff --git a/test/Transforms/InstCombine/2008-01-13-AndCmpCmp.ll b/test/Transforms/InstCombine/2008-01-13-AndCmpCmp.ll new file mode 100644 index 00000000000..71d5bf762c3 --- /dev/null +++ b/test/Transforms/InstCombine/2008-01-13-AndCmpCmp.ll @@ -0,0 +1,9 @@ +; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep and +; PR1907 + +define i1 @test(i32 %c84.17) { + %tmp2696 = icmp ne i32 %c84.17, 34 ; [#uses=2] + %tmp2699 = icmp sgt i32 %c84.17, -1 ; [#uses=1] + %tmp2703 = and i1 %tmp2696, %tmp2699 ; [#uses=1] + ret i1 %tmp2703 +}