CodeGen: Clear the MFI's save and restore point after PrologEpilogInserter

This state is no longer useful and not guaranteed to be valid in later
codegen passes. For example, see the added test, which would print a
savepoint of %bb.-1 without this change, and crashes with a
use-after-free error under ASan if you apply the recycling allocator
patch from llvm.org/PR26808.

llvm-svn: 266150

1 files changed, 2 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/PrologEpilogInserter.cpp b/llvm/lib/CodeGen/PrologEpilogInserter.cpp
index 7c3fe33cf75..2c3ea316e23 100644
--- a/llvm/lib/CodeGen/PrologEpilogInserter.cpp
+++ b/llvm/lib/CodeGen/PrologEpilogInserter.cpp
@@ -238,6 +238,8 @@ bool PEI::runOnMachineFunction(MachineFunction &Fn) {
   delete RS;
   SaveBlocks.clear();
   RestoreBlocks.clear();
+  MFI->setSavePoint(nullptr);
+  MFI->setRestorePoint(nullptr);
   return true;
 }