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| author | Chris Lattner <sabre@nondot.org> | 2011-01-15 07:36:13 +0000 |
|---|---|---|
| committer | Chris Lattner <sabre@nondot.org> | 2011-01-15 07:36:13 +0000 |
| commit | eeba3f5695e39ca970a7aeb161558575216005b2 (patch) | |
| tree | 2f42b2f1c59fe0888c4357c3a3b0f68db85a29fb | |
| parent | 1a8943a1f872a47b821fe7075f07b42403fa1a3f (diff) | |
| download | external_llvm-eeba3f5695e39ca970a7aeb161558575216005b2.zip external_llvm-eeba3f5695e39ca970a7aeb161558575216005b2.tar.gz external_llvm-eeba3f5695e39ca970a7aeb161558575216005b2.tar.bz2 | |
fix rdar://8785296 - -fcatch-undefined-behavior generates inefficient code
The basic issue is that isel (very reasonably!) expects conditional branches
to be folded, so CGP leaving around a bunch dead computation feeding
conditional branches isn't such a good idea. Just fold branches on constants
into unconditional branches.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123526 91177308-0d34-0410-b5e6-96231b3b80d8
| -rw-r--r-- | lib/Transforms/Scalar/CodeGenPrepare.cpp | 3 | ||||
| -rw-r--r-- | test/Transforms/CodeGenPrepare/basic.ll | 5 |
2 files changed, 7 insertions, 1 deletions
diff --git a/lib/Transforms/Scalar/CodeGenPrepare.cpp b/lib/Transforms/Scalar/CodeGenPrepare.cpp index 72c8bf3..3496aa2 100644 --- a/lib/Transforms/Scalar/CodeGenPrepare.cpp +++ b/lib/Transforms/Scalar/CodeGenPrepare.cpp @@ -1071,6 +1071,9 @@ bool CodeGenPrepare::OptimizeInst(Instruction *I) { if (CallInst *CI = dyn_cast<CallInst>(I)) return OptimizeCallInst(CI); + if (isa<TerminatorInst>(I)) + return ConstantFoldTerminator(I->getParent()); + return false; } diff --git a/test/Transforms/CodeGenPrepare/basic.ll b/test/Transforms/CodeGenPrepare/basic.ll index c3e57b4..a1cdf45 100644 --- a/test/Transforms/CodeGenPrepare/basic.ll +++ b/test/Transforms/CodeGenPrepare/basic.ll @@ -4,13 +4,16 @@ target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f3 target triple = "x86_64-apple-darwin10.0.0" ; CHECK: @test1 +; objectsize should fold to a constant, which causes the branch to fold to an +; uncond branch. +; rdar://8785296 define i32 @test1(i8* %ptr) nounwind ssp noredzone align 2 { entry: %0 = tail call i64 @llvm.objectsize.i64(i8* %ptr, i1 false) %1 = icmp ugt i64 %0, 3 br i1 %1, label %T, label %trap -; CHECK: br i1 true, label +; CHECK: br label %T trap: ; preds = %0, %entry tail call void @llvm.trap() noreturn nounwind unreachable |