Fix PR 4626, a crash in branch folding after OptimizeBlock
produced a CFG it wasn't prepared for.
llvm-svn: 78351
diff --git a/llvm/lib/CodeGen/BranchFolding.cpp b/llvm/lib/CodeGen/BranchFolding.cpp
index 193bbb6..d25152b 100644
--- a/llvm/lib/CodeGen/BranchFolding.cpp
+++ b/llvm/lib/CodeGen/BranchFolding.cpp
@@ -893,8 +893,24 @@
while (!MBB->pred_empty()) {
MachineBasicBlock *Pred = *(MBB->pred_end()-1);
Pred->ReplaceUsesOfBlockWith(MBB, FallThrough);
+ // If this resulted in a predecessor with true and false edges
+ // both going to the fallthrough block, clean up;
+ // BranchFolding doesn't like this.
+ MachineBasicBlock::succ_iterator SI = Pred->succ_begin();
+ bool found = false;
+ while (SI != Pred->succ_end()) {
+ if (*SI == FallThrough) {
+ if (!found) {
+ found = true;
+ ++SI;
+ } else {
+ SI = Pred->removeSuccessor(SI);
+ }
+ } else {
+ ++SI;
+ }
+ }
}
-
// If MBB was the target of a jump table, update jump tables to go to the
// fallthrough instead.
MBB->getParent()->getJumpTableInfo()->