From 8e86929e3ce3fe56295d2704b93bf14c709b311a Mon Sep 17 00:00:00 2001
From: Jakob Stoklund Olesen <stoklund@2pi.dk>
Date: Sun, 20 May 2012 06:38:32 +0000
Subject: [PATCH] Properly constrain register classes in 2-addr.

X86 has 2-addr instructions with different constraints on the tied def
and use operands. One is GR32, one is GR32_NOSP.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157149 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/TwoAddressInstructionPass.cpp | 6 ++++++
 test/CodeGen/X86/shift-folding.ll         | 2 +-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/lib/CodeGen/TwoAddressInstructionPass.cpp b/lib/CodeGen/TwoAddressInstructionPass.cpp
index 8164690e40a..5218aa1f7a8 100644
--- a/lib/CodeGen/TwoAddressInstructionPass.cpp
+++ b/lib/CodeGen/TwoAddressInstructionPass.cpp
@@ -1555,6 +1555,12 @@ bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &MF) {
             MO.setIsKill(false);
             RemovedKillFlag = true;
           }
+
+          // Make sure regA is a legal regclass for the SrcIdx operand.
+          if (TargetRegisterInfo::isVirtualRegister(regA) &&
+              TargetRegisterInfo::isVirtualRegister(regB))
+            MRI->constrainRegClass(regA, MRI->getRegClass(regB));
+
           MO.setReg(regA);
 
           if (isCopy)
diff --git a/test/CodeGen/X86/shift-folding.ll b/test/CodeGen/X86/shift-folding.ll
index 3ea601147bb..c518cdd3aa4 100644
--- a/test/CodeGen/X86/shift-folding.ll
+++ b/test/CodeGen/X86/shift-folding.ll
@@ -1,4 +1,4 @@
-; RUN: llc < %s -march=x86 | FileCheck %s
+; RUN: llc < %s -march=x86 -verify-coalescing | FileCheck %s
 
 define i32* @test1(i32* %P, i32 %X) {
 ; CHECK: test1: