From f12c95a8af22771845fa16253ad04e90741f5602 Mon Sep 17 00:00:00 2001 From: Bob Wilson Date: Tue, 7 Aug 2012 22:35:16 +0000 Subject: [PATCH] Fix a serious typo in InstCombine's optimization of comparisons. An unsigned value converted to floating-point will always be greater than a negative constant. Unfortunately InstCombine reversed the check so that unsigned values were being optimized to always be greater than all positive floating-point constants. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161452 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/InstCombine/InstCombineCompares.cpp | 2 +- test/Transforms/InstCombine/2008-11-08-FCmp.ll | 9 +++++++++ 2 files changed, 10 insertions(+), 1 deletion(-) diff --git a/lib/Transforms/InstCombine/InstCombineCompares.cpp b/lib/Transforms/InstCombine/InstCombineCompares.cpp index 7076d88554d..bdd310e97f6 100644 --- a/lib/Transforms/InstCombine/InstCombineCompares.cpp +++ b/lib/Transforms/InstCombine/InstCombineCompares.cpp @@ -2824,7 +2824,7 @@ Instruction *InstCombiner::FoldFCmp_IntToFP_Cst(FCmpInst &I, case ICmpInst::ICMP_UGE: // (float)int >= -4.4 --> true // (float)int >= 4.4 --> int > 4 - if (!RHS.isNegative()) + if (RHS.isNegative()) return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); Pred = ICmpInst::ICMP_UGT; break; diff --git a/test/Transforms/InstCombine/2008-11-08-FCmp.ll b/test/Transforms/InstCombine/2008-11-08-FCmp.ll index c636288661b..f33a1f59f61 100644 --- a/test/Transforms/InstCombine/2008-11-08-FCmp.ll +++ b/test/Transforms/InstCombine/2008-11-08-FCmp.ll @@ -45,3 +45,12 @@ define i1 @test6(i32 %val) { ret i1 %2 ; CHECK: ret i1 false } + +; Check that optimizing unsigned >= comparisons correctly distinguishes +; positive and negative constants. +define i1 @test7(i32 %val) { + %1 = uitofp i32 %val to double + %2 = fcmp oge double %1, 3.200000e+00 + ret i1 %2 +; CHECK: icmp ugt i32 %val, 3 +} -- 2.34.1