Avoid folding loads that are unsafe to move.
LiveRangeEdit::foldAsLoad() can eliminate a register by folding a load
into its only use. Only do that when the load is safe to move, and it
won't extend any live ranges.
This fixes PR13414.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160575 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/LiveRangeEdit.cpp b/lib/CodeGen/LiveRangeEdit.cpp
index 261d860..896fdbf 100644
--- a/lib/CodeGen/LiveRangeEdit.cpp
+++ b/lib/CodeGen/LiveRangeEdit.cpp
@@ -177,6 +177,19 @@
if (!DefMI || !UseMI)
return false;
+ // Since we're moving the DefMI load, make sure we're not extending any live
+ // ranges.
+ if (!allUsesAvailableAt(DefMI,
+ LIS.getInstructionIndex(DefMI),
+ LIS.getInstructionIndex(UseMI)))
+ return false;
+
+ // We also need to make sure it is safe to move the load.
+ // Assume there are stores between DefMI and UseMI.
+ bool SawStore = true;
+ if (!DefMI->isSafeToMove(&TII, 0, SawStore))
+ return false;
+
DEBUG(dbgs() << "Try to fold single def: " << *DefMI
<< " into single use: " << *UseMI);