From 36c4debc94e7c68c769dfda781851a0c963dd746 Mon Sep 17 00:00:00 2001 From: Owen Anderson Date: Wed, 29 Sep 2010 20:34:41 +0000 Subject: [PATCH] Fix PR8247: JumpThreading can cause a block to become unreachable while still having predecessor, if it is part of a self-loop. Because of this, we cannot use the Simplify* APIs, as they can assert-fail on unreachable code. Since it's not easy to determine if a given threading will cause a block to become unreachable, simply defer simplifying simplification to later InstCombine and/or DCE passes. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@115082 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/Scalar/JumpThreading.cpp | 8 ++++---- test/Transforms/JumpThreading/crash.ll | 27 +++++++++++++++++++++++++ 2 files changed, 31 insertions(+), 4 deletions(-) diff --git a/lib/Transforms/Scalar/JumpThreading.cpp b/lib/Transforms/Scalar/JumpThreading.cpp index ce99afb1b65..43460beb3bd 100644 --- a/lib/Transforms/Scalar/JumpThreading.cpp +++ b/lib/Transforms/Scalar/JumpThreading.cpp @@ -613,7 +613,7 @@ bool JumpThreading::ProcessBlock(BasicBlock *BB) { TerminatorInst *BBTerm = BB->getTerminator(); for (unsigned i = 0, e = BBTerm->getNumSuccessors(); i != e; ++i) { if (i == BestSucc) continue; - RemovePredecessorAndSimplify(BBTerm->getSuccessor(i), BB, TD); + BBTerm->getSuccessor(i)->removePredecessor(BB, true); } DEBUG(dbgs() << " In block '" << BB->getName() @@ -664,7 +664,7 @@ bool JumpThreading::ProcessBlock(BasicBlock *BB) { if (PI == PE) { unsigned ToRemove = Baseline == LazyValueInfo::True ? 1 : 0; unsigned ToKeep = Baseline == LazyValueInfo::True ? 0 : 1; - RemovePredecessorAndSimplify(CondBr->getSuccessor(ToRemove), BB, TD); + CondBr->getSuccessor(ToRemove)->removePredecessor(BB, true); BranchInst::Create(CondBr->getSuccessor(ToKeep), CondBr); CondBr->eraseFromParent(); return true; @@ -1470,7 +1470,7 @@ bool JumpThreading::ThreadEdge(BasicBlock *BB, TerminatorInst *PredTerm = PredBB->getTerminator(); for (unsigned i = 0, e = PredTerm->getNumSuccessors(); i != e; ++i) if (PredTerm->getSuccessor(i) == BB) { - RemovePredecessorAndSimplify(BB, PredBB, TD); + BB->removePredecessor(PredBB, true); PredTerm->setSuccessor(i, NewBB); } @@ -1620,7 +1620,7 @@ bool JumpThreading::DuplicateCondBranchOnPHIIntoPred(BasicBlock *BB, // PredBB no longer jumps to BB, remove entries in the PHI node for the edge // that we nuked. - RemovePredecessorAndSimplify(BB, PredBB, TD); + BB->removePredecessor(PredBB, true); // Remove the unconditional branch at the end of the PredBB block. OldPredBranch->eraseFromParent(); diff --git a/test/Transforms/JumpThreading/crash.ll b/test/Transforms/JumpThreading/crash.ll index 751bc6518a1..aed51a1c9ee 100644 --- a/test/Transforms/JumpThreading/crash.ll +++ b/test/Transforms/JumpThreading/crash.ll @@ -484,3 +484,30 @@ bb269.us.us: bb288.bb289.loopexit_crit_edge: unreachable } + +; PR 8247 +%struct.S1 = type { i8, i8 } +@func_89.l_245 = internal constant %struct.S1 { i8 33, i8 6 }, align 1 +define void @func_89(i16 zeroext %p_90, %struct.S1* nocapture %p_91, i32* nocapture %p_92) nounwind ssp { +entry: + store i32 0, i32* %p_92, align 4 + br i1 false, label %lbl_260, label %if.else + +if.else: ; preds = %entry + br label %for.cond + +for.cond: ; preds = %lbl_260, %if.else + %l_245.0 = phi i16 [ %l_245.1, %lbl_260 ], [ 33, %if.else ] + %l_261.0 = phi i32 [ %and, %lbl_260 ], [ 255, %if.else ] + %tobool21 = icmp ult i16 %l_245.0, 256 + br i1 %tobool21, label %if.end, label %lbl_260 + +lbl_260: ; preds = %for.cond, %entry + %l_245.1 = phi i16 [ 1569, %entry ], [ %l_245.0, %for.cond ] + %l_261.1 = phi i32 [ 255, %entry ], [ %l_261.0, %for.cond ] + %and = and i32 %l_261.1, 1 + br label %for.cond + +if.end: ; preds = %for.cond + ret void +} -- 2.34.1