From 8df83c4a240293463700b0b97ca9e5425878c0ef Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Sat, 15 Jan 2011 07:36:13 +0000 Subject: [PATCH] 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. llvm-svn: 123526 --- llvm/lib/Transforms/Scalar/CodeGenPrepare.cpp | 3 +++ llvm/test/Transforms/CodeGenPrepare/basic.ll | 5 ++++- 2 files changed, 7 insertions(+), 1 deletion(-) diff --git a/llvm/lib/Transforms/Scalar/CodeGenPrepare.cpp b/llvm/lib/Transforms/Scalar/CodeGenPrepare.cpp index 72c8bf30477d..3496aa20abb1 100644 --- a/llvm/lib/Transforms/Scalar/CodeGenPrepare.cpp +++ b/llvm/lib/Transforms/Scalar/CodeGenPrepare.cpp @@ -1071,6 +1071,9 @@ bool CodeGenPrepare::OptimizeInst(Instruction *I) { if (CallInst *CI = dyn_cast(I)) return OptimizeCallInst(CI); + if (isa(I)) + return ConstantFoldTerminator(I->getParent()); + return false; } diff --git a/llvm/test/Transforms/CodeGenPrepare/basic.ll b/llvm/test/Transforms/CodeGenPrepare/basic.ll index c3e57b4d206f..a1cdf4555362 100644 --- a/llvm/test/Transforms/CodeGenPrepare/basic.ll +++ b/llvm/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