commit 9d9041cc83619436c5e212b06509d3f5fbb860d7
author Manoj Gupta <manojgupta@google.com> Tue Aug 01 15:39:12 2017 +0000
committer Stephen Hines <srhines@google.com> Tue Sep 26 23:50:31 2017 -0700
tree e03d035c4611e8144ec3d8119ed1e6ee3e4702b1
parent 1128b7e8de97275a3831fca14f05c999e5b52071

[X86] Fix a crash in FEntryInserter Pass.

Summary:
FEntryInserter pass unconditionally derefs the first Instruction
in the first Basic Block. The pass crashes when the first
BasicBlock is empty. Fix the crash by not dereferencing the basic
Block iterator. This fixes an issue observed when building Linux kernel
4.4 with clang.

Fixes PR33971.

Reviewers: hfinkel, niravd, dblaikie

Reviewed By: niravd

Subscribers: davide, llvm-commits

Differential Revision: https://reviews.llvm.org/D35979

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@309694 91177308-0d34-0410-b5e6-96231b3b80d8