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);
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.
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 =
--- /dev/null
+; 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
+}
+