From 26b86a0b5676253040dc206b437536a24306fb76 Mon Sep 17 00:00:00 2001
From: David Greene <greened@obbligato.org>
Date: Mon, 27 Oct 2008 17:38:59 +0000
Subject: [PATCH] Fix PR2634.  Create new virtual registers from spills early
 so that we can give it the same stack slot as the spilled interval if it is
 folded. This prevents the fold/unfold code from pointing to the wrong
 register.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@58255 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/LiveIntervalAnalysis.cpp | 27 +++++++++++++++++++--------
 1 file changed, 19 insertions(+), 8 deletions(-)

diff --git a/lib/CodeGen/LiveIntervalAnalysis.cpp b/lib/CodeGen/LiveIntervalAnalysis.cpp
index 31a34a5b359..c91adbadaee 100644
--- a/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -1231,6 +1231,17 @@ rewriteInstructionForSpills(const LiveInterval &li, const VNInfo *VNI,
       if (!TrySplit)
       SSWeight += Weight;
 
+    // Create a new virtual register for the spill interval.
+    // Create the new register now so we can map the fold instruction
+    // to the new register so when it is unfolded we get the correct
+    // answer.
+    bool CreatedNewVReg = false;
+    if (NewVReg == 0) {
+      NewVReg = mri_->createVirtualRegister(rc);
+      vrm.grow();
+      CreatedNewVReg = true;
+    }
+
     if (!TryFold)
       CanFold = false;
     else {
@@ -1238,9 +1249,16 @@ rewriteInstructionForSpills(const LiveInterval &li, const VNInfo *VNI,
       // optimal point to insert a load / store later.
       if (!TrySplit) {
         if (tryFoldMemoryOperand(MI, vrm, ReMatDefMI, index,
-                                 Ops, FoldSS, FoldSlot, Reg)) {
+                                 Ops, FoldSS, FoldSlot, NewVReg)) {
           // Folding the load/store can completely change the instruction in
           // unpredictable ways, rescan it from the beginning.
+
+          if (FoldSS) {
+            // We need to give the new vreg the same stack slot as the
+            // spilled interval.
+            vrm.assignVirt2StackSlot(NewVReg, FoldSlot);
+          }
+
           HasUse = false;
           HasDef = false;
           CanFold = false;
@@ -1256,13 +1274,6 @@ rewriteInstructionForSpills(const LiveInterval &li, const VNInfo *VNI,
       }
     }
 
-    // Create a new virtual register for the spill interval.
-    bool CreatedNewVReg = false;
-    if (NewVReg == 0) {
-      NewVReg = mri_->createVirtualRegister(rc);
-      vrm.grow();
-      CreatedNewVReg = true;
-    }
     mop.setReg(NewVReg);
     if (mop.isImplicit())
       rewriteImplicitOps(li, MI, NewVReg, vrm);
-- 
2.34.1