Make the peephole optimizer clear kill flags on a vreg if it's about to add new
uses of the vreg, since the old kills may no longer be valid. This was causing
-verify-machineinstrs to complain about uses after kills, and could potentially
have been causing subtle register allocation issues, but I haven't come across a
test case yet.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151425 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/PeepholeOptimizer.cpp b/lib/CodeGen/PeepholeOptimizer.cpp
index 203f2bf..9c5c029 100644
--- a/lib/CodeGen/PeepholeOptimizer.cpp
+++ b/lib/CodeGen/PeepholeOptimizer.cpp
@@ -237,6 +237,10 @@
if (PHIBBs.count(UseMBB))
continue;
+ // About to add uses of DstReg, clear DstReg's kill flags.
+ if (!Changed)
+ MRI->clearKillFlags(DstReg);
+
unsigned NewVR = MRI->createVirtualRegister(RC);
BuildMI(*UseMBB, UseMI, UseMI->getDebugLoc(),
TII->get(TargetOpcode::COPY), NewVR)