[regalloc][WinEH] Do not mark intervals as not spillable if they contain a regmask

Differential Revision: http://reviews.llvm.org/D16831

llvm-svn: 260164

2 files changed, 39 insertions, 2 deletions

diff --git a/llvm/lib/CodeGen/CalcSpillWeights.cpp b/llvm/lib/CodeGen/CalcSpillWeights.cpp
index abc655ac34c..26aa46fb6c2 100644
--- a/llvm/lib/CodeGen/CalcSpillWeights.cpp
+++ b/llvm/lib/CodeGen/CalcSpillWeights.cpp
@@ -213,8 +213,11 @@ VirtRegAuxInfo::calculateSpillWeightAndHint(LiveInterval &li) {
   if (!Spillable)
     return;
 
-  // Mark li as unspillable if all live ranges are tiny.
-  if (li.isZeroLength(LIS.getSlotIndexes())) {
+  // Mark li as unspillable if all live ranges are tiny and the interval
+  // is not live at any reg mask.  If the interval is live at a reg mask
+  // spilling may be required.
+  if (li.isZeroLength(LIS.getSlotIndexes()) &&
+      !li.isLiveAtIndexes(LIS.getRegMaskSlots())) {
     li.markNotSpillable();
     return;
   }
diff --git a/llvm/lib/CodeGen/LiveInterval.cpp b/llvm/lib/CodeGen/LiveInterval.cpp
index 90d01f69238..d80acc0c7f9 100644
--- a/llvm/lib/CodeGen/LiveInterval.cpp
+++ b/llvm/lib/CodeGen/LiveInterval.cpp
@@ -748,6 +748,40 @@ void LiveRange::flushSegmentSet() {
   verify();
 }
 
+bool LiveRange::isLiveAtIndexes(ArrayRef<SlotIndex> Slots) const {
+  ArrayRef<SlotIndex>::iterator SlotI = Slots.begin();
+  ArrayRef<SlotIndex>::iterator SlotE = Slots.end();
+
+  // If there are no regmask slots, we have nothing to search.
+  if (SlotI == SlotE)
+    return false;
+
+  // Start our search at the first segment that ends after the first slot.
+  const_iterator SegmentI = find(*SlotI);
+  const_iterator SegmentE = end();
+
+  // If there are no segments that end after the first slot, we're done.
+  if (SegmentI == SegmentE)
+    return false;
+
+  // Look for each slot in the live range.
+  for ( ; SlotI != SlotE; ++SlotI) {
+    // Go to the next segment that ends after the current slot.
+    // The slot may be within a hole in the range.
+    SegmentI = advanceTo(SegmentI, *SlotI);
+    if (SegmentI == SegmentE)
+      return false;
+
+    // If this segment contains the slot, we're done.
+    if (SegmentI->contains(*SlotI))
+      return true;
+    // Otherwise, look for the next slot.
+  }
+
+  // We didn't find a segment containing any of the slots.
+  return false;
+}
+
 void LiveInterval::freeSubRange(SubRange *S) {
   S->~SubRange();
   // Memory was allocated with BumpPtr allocator and is not freed here.