Fix RegScavenger::unprocess

RegScavenger::unprocess walks backward, so it should undo the effects
of defs before undoing effects of kills. Previously it did things in
the opposite order, leaving a register apparently unused (dead) in the
case where an instruction both used (killed) and defined a register.

Differential Revision: https://reviews.llvm.org/D42200

llvm-svn: 337735

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/lib/CodeGen/RegisterScavenging.cpp b/llvm/lib/CodeGen/RegisterScavenging.cpp
index d7cd5a096ef..a878c34f9aa 100644
--- a/llvm/lib/CodeGen/RegisterScavenging.cpp
+++ b/llvm/lib/CodeGen/RegisterScavenging.cpp
@@ -162,8 +162,8 @@ void RegScavenger::unprocess() {
     determineKillsAndDefs();
 
     // Commit the changes.
-    setUsed(KillRegUnits);
     setUnused(DefRegUnits);
+    setUsed(KillRegUnits);
   }
 
   if (MBBI == MBB->begin()) {