diff options
| author | Chandler Carruth <chandlerc@gmail.com> | 2012-03-21 10:58:47 +0000 |
|---|---|---|
| committer | Chandler Carruth <chandlerc@gmail.com> | 2012-03-21 10:58:47 +0000 |
| commit | ff739c1575df58f3926c2f3b6e00a6c45f773523 (patch) | |
| tree | a63bafdd55909e0c834d5d27773e7e8aefc0b3d7 | |
| parent | a8d873e178d45024db9c0ef6a25c6867424785f7 (diff) | |
Teach instsimplify to gracefully degrade in the presence of instructions
not attched to a basic block or function. There are conservatively
correct answers in these cases, and this makes the analysis more useful
in contexts where we have a partially formed bit of IR.
I don't have any way to test this directly... suggestions welcome here,
but I'm not seeing anything sadly. I only found this using a subsequent
patch to the inliner which runs instsimplify on partially inlined
instructions, and even then only on a quite large program. I never got
a reasonable testcase out of it, and anything I do get is likely to be
quite fragile due to requiring an interaction of two different passes,
and the only result being a segfault if it goes wrong.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153176 91177308-0d34-0410-b5e6-96231b3b80d8
| -rw-r--r-- | lib/Analysis/InstructionSimplify.cpp | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp index f8d159dc43..72e33d1862 100644 --- a/lib/Analysis/InstructionSimplify.cpp +++ b/lib/Analysis/InstructionSimplify.cpp @@ -95,6 +95,12 @@ static bool ValueDominatesPHI(Value *V, PHINode *P, const DominatorTree *DT) { // Arguments and constants dominate all instructions. return true; + // If we are processing instructions (and/or basic blocks) that have not been + // fully added to a function, the parent nodes may still be null. Simply + // return the conservative answer in these cases. + if (!I->getParent() || !P->getParent() || !I->getParent()->getParent()) + return false; + // If we have a DominatorTree then do a precise test. if (DT) { if (!DT->isReachableFromEntry(P->getParent())) |