CodeGen: Avoid dereferencing end() in MachineScheduler
Check MachineInstr::isDebugValue for the same instruction as we're
calling isSchedBoundary, avoiding the possibility of dereferencing
end().
This is a functionality change even when I!=end(). Matthias had a look
and agrees this is the right resolution (as opposed to checking for
end()).
This is triggered by a huge number of tests, but they happen to
magically pass right now. I found this because WIP patches for PR26753
convert them into crashes.
llvm-svn: 278394
diff --git a/llvm/lib/CodeGen/MachineScheduler.cpp b/llvm/lib/CodeGen/MachineScheduler.cpp
index d921e29..01ef9d8 100644
--- a/llvm/lib/CodeGen/MachineScheduler.cpp
+++ b/llvm/lib/CodeGen/MachineScheduler.cpp
@@ -458,9 +458,10 @@
unsigned NumRegionInstrs = 0;
MachineBasicBlock::iterator I = RegionEnd;
for (;I != MBB->begin(); --I) {
- if (isSchedBoundary(&*std::prev(I), &*MBB, MF, TII))
+ MachineInstr &MI = *std::prev(I);
+ if (isSchedBoundary(&MI, &*MBB, MF, TII))
break;
- if (!I->isDebugValue())
+ if (!MI.isDebugValue())
++NumRegionInstrs;
}
// Notify the scheduler of the region, even if we may skip scheduling