If llvm.dbg.value and the value instruction it refers to are far apart then iSel may not be able to find corresponding Node for llvm.dbg.value during DAG construction. Make iSel's life easier by removing this distance between llvm.dbg.value and its value instruction.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@132151 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/CodeGenPrepare.cpp b/lib/Transforms/Scalar/CodeGenPrepare.cpp
index 483bfe3..7ba92ba 100644
--- a/lib/Transforms/Scalar/CodeGenPrepare.cpp
+++ b/lib/Transforms/Scalar/CodeGenPrepare.cpp
@@ -548,7 +548,19 @@
// From here on out we're working with named functions.
if (CI->getCalledFunction() == 0) return false;
-
+
+ // llvm.dbg.value is far away from the value then iSel may not be able
+ // handle it properly. iSel will drop llvm.dbg.value if it can not
+ // find a node corresponding to the value.
+ if (DbgValueInst *DVI = dyn_cast<DbgValueInst>(CI))
+ if (Instruction *VI = dyn_cast_or_null<Instruction>(DVI->getValue()))
+ if (DVI->getParent() != VI->getParent() || DT->dominates(DVI, VI)) {
+ DEBUG(dbgs() << "Moving Debug Value before :\n" << *DVI << ' ' << *VI);
+ DVI->removeFromParent();
+ DVI->insertAfter(VI);
+ return true;
+ }
+
// We'll need TargetData from here on out.
const TargetData *TD = TLI ? TLI->getTargetData() : 0;
if (!TD) return false;