From e7fbdcdfc6b5e562d2741cceec8aee1bd3dd1c2d Mon Sep 17 00:00:00 2001
From: Jakob Stoklund Olesen <stoklund@2pi.dk>
Date: Fri, 19 Nov 2010 05:45:24 +0000
Subject: [PATCH] Don't attempt trivial coalescing for sub-register copies.

Patch by Krister Wombell!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@119791 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/RegAllocLinearScan.cpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lib/CodeGen/RegAllocLinearScan.cpp b/lib/CodeGen/RegAllocLinearScan.cpp
index c0720fe9d13..ac5143b7c69 100644
--- a/lib/CodeGen/RegAllocLinearScan.cpp
+++ b/lib/CodeGen/RegAllocLinearScan.cpp
@@ -466,6 +466,10 @@ unsigned RALinScan::attemptTrivialCoalescing(LiveInterval &cur, unsigned Reg) {
       CandReg = CopyMI->getOperand(0).getReg();
     else
       return Reg;
+
+    // If the target of the copy is a sub-register then don't coalesce.
+    if(CopyMI->getOperand(0).getSubReg())
+      return Reg;
   }
 
   if (TargetRegisterInfo::isVirtualRegister(CandReg)) {