diff options
| -rw-r--r-- | lib/Transforms/Utils/SimplifyCFG.cpp | 15 | ||||
| -rw-r--r-- | test/Transforms/SimplifyCFG/2009-01-19-UnconditionalTrappingConstantExpr.ll | 20 |
2 files changed, 34 insertions, 1 deletions
diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp index b0feadffad..4abc2eb042 100644 --- a/lib/Transforms/Utils/SimplifyCFG.cpp +++ b/lib/Transforms/Utils/SimplifyCFG.cpp @@ -1423,11 +1423,21 @@ static bool FoldBranchToCommonDest(BranchInst *BI) { if ((!isa<CmpInst>(Cond) && !isa<BinaryOperator>(Cond)) || Cond->getParent() != BB || &BB->front() != Cond || !Cond->hasOneUse()) return false; - + // Make sure the instruction after the condition is the cond branch. BasicBlock::iterator CondIt = Cond; ++CondIt; if (&*CondIt != BI) return false; + + // Cond is known to be a compare or binary operator. Check to make sure that + // neither operand is a potentially-trapping constant expression. + if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Cond->getOperand(0))) + if (CE->canTrap()) + return false; + if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Cond->getOperand(1))) + if (CE->canTrap()) + return false; + // Finally, don't infinitely unroll conditional loops. BasicBlock *TrueDest = BI->getSuccessor(0); @@ -1438,6 +1448,7 @@ static bool FoldBranchToCommonDest(BranchInst *BI) { for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) { BasicBlock *PredBlock = *PI; BranchInst *PBI = dyn_cast<BranchInst>(PredBlock->getTerminator()); + // Check that we have two conditional branches. If there is a PHI node in // the common successor, verify that the same value flows in from both // blocks. @@ -1459,6 +1470,8 @@ static bool FoldBranchToCommonDest(BranchInst *BI) { else continue; + DOUT << "FOLDING BRANCH TO COMMON DEST:\n" << *PBI << *BB; + // If we need to invert the condition in the pred block to match, do so now. if (InvertPredCond) { Value *NewCond = diff --git a/test/Transforms/SimplifyCFG/2009-01-19-UnconditionalTrappingConstantExpr.ll b/test/Transforms/SimplifyCFG/2009-01-19-UnconditionalTrappingConstantExpr.ll new file mode 100644 index 0000000000..0bc6bdb895 --- /dev/null +++ b/test/Transforms/SimplifyCFG/2009-01-19-UnconditionalTrappingConstantExpr.ll @@ -0,0 +1,20 @@ +; RUN: llvm-as < %s | opt -simplifycfg | llvm-dis | grep {br i1 } | count 2 +; PR3354 +; Do not merge bb1 into the entry block, it might trap. + +@G = extern_weak global i32 + +define i32 @test(i32 %tmp21, i32 %tmp24) { + %tmp25 = icmp sle i32 %tmp21, %tmp24 + br i1 %tmp25, label %bb2, label %bb1 + +bb1: ; preds = %bb + %tmp26 = icmp sgt i32 sdiv (i32 -32768, i32 ptrtoint (i32* @G to i32)), 0 + br i1 %tmp26, label %bb6, label %bb2 +bb2: + ret i32 42 + +bb6: + unwind +} + |