Fix bug when atomic load is fused with an arith op (and not in the entry BB)

src/IceTargetLowering.cpp

Index: src/IceTargetLowering.cpp
diff --git a/src/IceTargetLowering.cpp b/src/IceTargetLowering.cpp
index 05ae1216547b4f6d7fe2d30d5f0d1ba1cb0d3555..f3eccc499858f5d23b2a81717d0bba1c61ca9a21 100644
--- a/src/IceTargetLowering.cpp
+++ b/src/IceTargetLowering.cpp
@@ -26,7 +26,8 @@ namespace Ice {
 
 void LoweringContext::init(CfgNode *N) {
   Node = N;
-  Cur = getNode()->getInsts().begin();
+  Begin = getNode()->getInsts().begin();
+  Cur = Begin;
   End = getNode()->getInsts().end();
   skipDeleted(Cur);
   Next = Cur;
@@ -50,6 +51,19 @@ void LoweringContext::advance(InstList::iterator &I) {
   }
 }
 
+void LoweringContext::rewind(InstList::iterator &I) const {
+  assert(I != Begin);
+  --I;

[Jim Stichnoth, 2014/07/29 17:54:09]

do {
  --I;
} while (I != Begin && (*I)->isDeleted());

[jvoung (off chromium), 2014/07/30 15:17:13]

Done.

+  while (I != Begin && (*I)->isDeleted())
+    --I;
+}
+
+Inst *LoweringContext::getLastInserted() const {
+  InstList::iterator Cursor = Next;
+  rewind(Cursor);
+  return *Cursor;
+}
+
 TargetLowering *TargetLowering::createLowering(TargetArch Target, Cfg *Func) {
   // These statements can be #ifdef'd to specialize the code generator
   // to a subset of the available targets.  TODO: use CRTP.