[PeepholeOptimizer] Update the kill flags when extending the live-range of the

source of a copy.

<rdar://problem/12702965>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216229 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/PeepholeOptimizer.cpp b/lib/CodeGen/PeepholeOptimizer.cpp
index ae14331d6630257a2b91cd64955307ce146bde79..98fcc2e2529560a98534f944924d018acf97a363 100644 (file)
--- a/lib/CodeGen/PeepholeOptimizer.cpp
+++ b/lib/CodeGen/PeepholeOptimizer.cpp
@@ -899,7 +899,11 @@ bool PeepholeOptimizer::optimizeCoalescableCopy(MachineInstr *MI) {
     if (!findNextSource(NewSrc, NewSubReg) || SrcReg == NewSrc)
       continue;
     // Rewrite source.
-    Changed |= CpyRewriter->RewriteCurrentSource(NewSrc, NewSubReg);
+    if (CpyRewriter->RewriteCurrentSource(NewSrc, NewSubReg)) {
+      // We may have extended the live-range of NewSrc, account for that.
+      MRI->clearKillFlags(NewSrc);
+      Changed = true;
+    }
   }
   // TODO: We could have a clean-up method to tidy the instruction.
   // E.g., v0 = INSERT_SUBREG v1, v1.sub0, sub0