Fix a bug where we could corrupt a parent loop's header info if we unrolled
a nested loop. This fixes Transforms/LoopUnroll/2005-03-06-BadLoopInfoUpdate.ll
and PR532
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@20493 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/LoopUnroll.cpp b/lib/Transforms/Scalar/LoopUnroll.cpp
index 8e62520..da80ee3 100644
--- a/lib/Transforms/Scalar/LoopUnroll.cpp
+++ b/lib/Transforms/Scalar/LoopUnroll.cpp
@@ -283,16 +283,27 @@
// Preheader.
Preheader->replaceAllUsesWith(LoopExit);
+ Function *F = LoopExit->getParent();
+ if (Parent) {
+ // Otherwise, if this is a sub-loop, and the preheader was the loop header
+ // of the parent loop, move the exit block to be the new parent loop header.
+ if (Parent->getHeader() == Preheader) {
+ assert(Parent->contains(LoopExit) &&
+ "Exit block isn't contained in parent?");
+ Parent->moveToHeader(LoopExit);
+ }
+ } else {
+ // If the preheader was the entry block of this function, move the exit
+ // block to be the new entry of the function.
+ if (Preheader == &F->front())
+ F->getBasicBlockList().splice(F->begin(),
+ F->getBasicBlockList(), LoopExit);
+ }
+
// Remove BB and LoopExit from our analyses.
LI->removeBlock(Preheader);
LI->removeBlock(BB);
- // If the preheader was the entry block of this function, move the exit block
- // to be the new entry of the loop.
- Function *F = LoopExit->getParent();
- if (Preheader == &F->front())
- F->getBasicBlockList().splice(F->begin(), F->getBasicBlockList(), LoopExit);
-
// Actually delete the blocks now.
F->getBasicBlockList().erase(Preheader);
F->getBasicBlockList().erase(BB);