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| author | Bob Wilson <bob.wilson@apple.com> | 2012-08-07 22:35:16 +0000 |
|---|---|---|
| committer | Bob Wilson <bob.wilson@apple.com> | 2012-08-07 22:35:16 +0000 |
| commit | f12c95a8af22771845fa16253ad04e90741f5602 (patch) | |
| tree | 104e6f1c380b0bb520c3b6f340ea55aa0d91a192 | |
| parent | b64dd5f2b5a9989a8b1006d0aa82428455da039a (diff) | |
| download | external_llvm-f12c95a8af22771845fa16253ad04e90741f5602.zip external_llvm-f12c95a8af22771845fa16253ad04e90741f5602.tar.gz external_llvm-f12c95a8af22771845fa16253ad04e90741f5602.tar.bz2 | |
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. <rdar://problem/12029145>
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161452 91177308-0d34-0410-b5e6-96231b3b80d8
| -rw-r--r-- | lib/Transforms/InstCombine/InstCombineCompares.cpp | 2 | ||||
| -rw-r--r-- | test/Transforms/InstCombine/2008-11-08-FCmp.ll | 9 |
2 files changed, 10 insertions, 1 deletions
diff --git a/lib/Transforms/InstCombine/InstCombineCompares.cpp b/lib/Transforms/InstCombine/InstCombineCompares.cpp index 7076d88..bdd310e 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 c636288..f33a1f5 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. <rdar://problem/12029145> +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 +} |