prevent jump threading from merging blocks when their address is
taken (and used!). This prevents merging the blocks (invalidating
the block addresses) in a case like this:
#define _THIS_IP_ ({ __label__ __here; __here: (unsigned long)&&__here; })
void foo() {
printf("%p\n", _THIS_IP_);
printf("%p\n", _THIS_IP_);
printf("%p\n", _THIS_IP_);
}
which fixes PR4151.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125829 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/JumpThreading.cpp b/lib/Transforms/Scalar/JumpThreading.cpp
index 3d218a6..90094a8 100644
--- a/lib/Transforms/Scalar/JumpThreading.cpp
+++ b/lib/Transforms/Scalar/JumpThreading.cpp
@@ -606,6 +606,16 @@
return MinSucc;
}
+static bool hasAddressTakenAndUsed(BasicBlock *BB) {
+ if (!BB->hasAddressTaken()) return false;
+
+ // If the block has its address taken, it may be a tree of dead constants
+ // hanging off of it. These shouldn't keep the block alive.
+ BlockAddress *BA = BlockAddress::get(BB);
+ BA->removeDeadConstantUsers();
+ return !BA->use_empty();
+}
+
/// ProcessBlock - If there are any predecessors whose control can be threaded
/// through to a successor, transform them now.
bool JumpThreading::ProcessBlock(BasicBlock *BB) {
@@ -621,7 +631,7 @@
// predecessors of our predecessor block.
if (BasicBlock *SinglePred = BB->getSinglePredecessor()) {
if (SinglePred->getTerminator()->getNumSuccessors() == 1 &&
- SinglePred != BB) {
+ SinglePred != BB && !hasAddressTakenAndUsed(BB)) {
// If SinglePred was a loop header, BB becomes one.
if (LoopHeaders.erase(SinglePred))
LoopHeaders.insert(BB);