From 969b9fe379c333bd5065d387da7b43ed90e001de Mon Sep 17 00:00:00 2001
From: Dale Johannesen <dalej@apple.com>
Date: Fri, 25 Jun 2010 00:49:43 +0000
Subject: [PATCH] Fix a case where an earlyclobber operand of an asm is reused
 as an input.  PR 4118.  Testcase is too big, as usual with bugs in this area,
 but there's one in the PR.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106816 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/VirtRegRewriter.cpp | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/lib/CodeGen/VirtRegRewriter.cpp b/lib/CodeGen/VirtRegRewriter.cpp
index 361d35e8a89..6370d8fa5cb 100644
--- a/lib/CodeGen/VirtRegRewriter.cpp
+++ b/lib/CodeGen/VirtRegRewriter.cpp
@@ -2033,6 +2033,21 @@ LocalRewriter::RewriteMBB(LiveIntervals *LIs,
           CanReuse = !ReusedOperands.isClobbered(PhysReg) &&
             Spills.canClobberPhysReg(PhysReg);
         }
+        // If this is an asm, and PhysReg is used elsewhere as an earlyclobber
+        // operand, we can't also use it as an input.  (Outputs always come
+        // before inputs, so we can stop looking at i.)
+        if (MI.getOpcode()==TargetOpcode::INLINEASM) {
+          for (unsigned k=0; k<i; ++k) {
+            MachineOperand &MOk = MI.getOperand(k);
+            if (!MOk.isReg() || MOk.getReg()==0)
+              continue;
+            unsigned VirtRegk = MOk.getReg();
+            if (VirtRegk == PhysReg && MOk.isEarlyClobber()) {
+              CanReuse = false;
+              break;
+            }
+          }
+        }
 
         if (CanReuse) {
           // If this stack slot value is already available, reuse it!
@@ -2103,6 +2118,8 @@ LocalRewriter::RewriteMBB(LiveIntervals *LIs,
         // To avoid this problem, and to avoid doing a load right after a store,
         // we emit a copy from PhysReg into the designated register for this
         // operand.
+        //
+        // This case also applies to an earlyclobber'd PhysReg.
         unsigned DesignatedReg = VRM->getPhys(VirtReg);
         assert(DesignatedReg && "Must map virtreg to physreg!");
 
-- 
2.34.1