Use a worklist to avoid a sneaky iterator invalidation.
The iterator could be invalidated when it's recursively deleting a whole bunch
of constant expressions in a constant initializer.
Note: This was only reproducible if `opt' was run on a `.bc' file. If `opt' was
run on a `.ll' file, it wouldn't crash. This is why the test first pushes the
`.ll' file through `llvm-as' before feeding it to `opt'.
PR15440
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178531 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/IPO/GlobalOpt.cpp b/lib/Transforms/IPO/GlobalOpt.cpp
index 2b9d667..b035a82 100644
--- a/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/lib/Transforms/IPO/GlobalOpt.cpp
@@ -470,8 +470,9 @@
static bool CleanupConstantGlobalUsers(Value *V, Constant *Init,
DataLayout *TD, TargetLibraryInfo *TLI) {
bool Changed = false;
- for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;) {
- User *U = *UI++;
+ SmallVector<User*, 8> WorkList(V->use_begin(), V->use_end());
+ while (!WorkList.empty()) {
+ User *U = WorkList.pop_back_val();
if (LoadInst *LI = dyn_cast<LoadInst>(U)) {
if (Init) {
@@ -534,7 +535,6 @@
// us, and if they are all dead, nuke them without remorse.
if (SafeToDestroyConstant(C)) {
C->destroyConstant();
- // This could have invalidated UI, start over from scratch.
CleanupConstantGlobalUsers(V, Init, TD, TLI);
return true;
}