From b4fbcbc288f89b839581eefa00289e249f167bd1 Mon Sep 17 00:00:00 2001
From: James Molloy <james.molloy@arm.com>
Date: Fri, 12 Sep 2014 16:55:26 +0000
Subject: [PATCH] [A57FPLoadBalancing] Ignore <def>s when checking if a chain
 may be killed.

Defs are seen before uses, so a def without the kill flag doesn't necessarily
mean that the register is not killed on that instruction. It may be killed
in a later use operand.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217689 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/AArch64/AArch64A57FPLoadBalancing.cpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lib/Target/AArch64/AArch64A57FPLoadBalancing.cpp b/lib/Target/AArch64/AArch64A57FPLoadBalancing.cpp
index f298e118210..361963b962b 100644
--- a/lib/Target/AArch64/AArch64A57FPLoadBalancing.cpp
+++ b/lib/Target/AArch64/AArch64A57FPLoadBalancing.cpp
@@ -662,6 +662,10 @@ maybeKillChain(MachineOperand &MO, unsigned Idx,
   // determine if a chain should be ended and remove from ActiveChains.
   MachineInstr *MI = MO.getParent();
 
+  if (MO.isReg() && MO.isDef())
+    // We don't care about defs. We see them before uses, so reject them early.
+    return;
+
   if (MO.isReg()) {
 
     // If this is a KILL of a current chain, record it.