[MustExecute] Fix a debug invariant issue in isGuaranteedToExecute()
Summary:
Look past debug intrinsics when querying whether an instruction is the
first instruction in the header block. The commit includes a reproducer
for a case where LICM would not hoist an instruction, due to the presence
of the intrinsic.
A caveat with this commit is that the check will not work properly if
the instruction at hand is a debug intrinsic. I assume that no one
depends on isGuaranteedToExecute() to return true for debug intrinsics
for these cases (and that this might be an indication of another debug
invariant issue), so I thought that it was not worth adding that extra
bit of complexity.
Reviewers: reames, anna
Reviewed By: anna
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D47197
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@333274 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed