[llvm] r287571 - Check proper live range in extendPHIRanges

[Krzysztof Parzyszek via llvm-commits]

Author: kparzysz
Date: Mon Nov 21 14:24:12 2016
New Revision: 287571

URL: http://llvm.org/viewvc/llvm-project?rev=287571&view=rev
Log:
Check proper live range in extendPHIRanges

The function extendPHIRanges checks the main range of the original live
interval, even when dealing with a subrange. This could also lead to an
assert when the subrange is not live at the extension point, but the
main range is. To avoid this, check the corresponding subrange of the
original live range, instead of always checking the main range.

Review (as a part of a bigger set of changes):
https://reviews.llvm.org/D26359

Modified:
    llvm/trunk/lib/CodeGen/SplitKit.cpp
    llvm/trunk/lib/CodeGen/SplitKit.h

Modified: llvm/trunk/lib/CodeGen/SplitKit.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SplitKit.cpp?rev=287571&r1=287570&r2=287571&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SplitKit.cpp (original)
+++ llvm/trunk/lib/CodeGen/SplitKit.cpp Mon Nov 21 14:24:12 2016
@@ -1092,13 +1092,19 @@ static bool removeDeadSegment(SlotIndex
 }
 
 void SplitEditor::extendPHIRange(MachineBasicBlock &B, LiveRangeCalc &LRC,
-                                 LiveRange &LR, ArrayRef<SlotIndex> Undefs) {
+                                 LiveRange &LR, LaneBitmask LM,
+                                 ArrayRef<SlotIndex> Undefs) {
   for (MachineBasicBlock *P : B.predecessors()) {
     SlotIndex End = LIS.getMBBEndIdx(P);
     SlotIndex LastUse = End.getPrevSlot();
     // The predecessor may not have a live-out value. That is OK, like an
     // undef PHI operand.
-    if (Edit->getParent().liveAt(LastUse))
+    LiveInterval &PLI = Edit->getParent();
+    // Need the cast because the inputs to ?: would otherwise be deemed
+    // "incompatible": SubRange vs LiveInterval.
+    LiveRange &PSR = (LM != ~0u) ? getSubRangeForMask(LM, PLI)
+                                 : static_cast<LiveRange&>(PLI);
+    if (PSR.liveAt(LastUse))
       LRC.extend(LR, End, /*PhysReg=*/0, Undefs);
   }
 }
@@ -1120,7 +1126,7 @@ void SplitEditor::extendPHIKillRanges()
     LiveRangeCalc &LRC = getLRCalc(RegIdx);
     MachineBasicBlock &B = *LIS.getMBBFromIndex(V->def);
     if (!removeDeadSegment(V->def, LI))
-      extendPHIRange(B, LRC, LI, /*Undefs=*/{});
+      extendPHIRange(B, LRC, LI, ~0u, /*Undefs=*/{});
   }
 
   SmallVector<SlotIndex, 4> Undefs;
@@ -1141,7 +1147,7 @@ void SplitEditor::extendPHIKillRanges()
                    &LIS.getVNInfoAllocator());
       Undefs.clear();
       LI.computeSubRangeUndefs(Undefs, PS.LaneMask, MRI, *LIS.getSlotIndexes());
-      extendPHIRange(B, SubLRC, S, Undefs);
+      extendPHIRange(B, SubLRC, S, PS.LaneMask, Undefs);
     }
   }
 }

Modified: llvm/trunk/lib/CodeGen/SplitKit.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SplitKit.h?rev=287571&r1=287570&r2=287571&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SplitKit.h (original)
+++ llvm/trunk/lib/CodeGen/SplitKit.h Mon Nov 21 14:24:12 2016
@@ -386,10 +386,14 @@ private:
   /// Return true if any ranges were skipped.
   bool transferValues();
 
-  /// Live range @p LR has a live PHI def at the beginning of block @p B.
-  /// Extend the range @p LR of all predecessor values that reach this def.
+  /// Live range @p LR corresponding to the lane Mask @p LM has a live
+  /// PHI def at the beginning of block @p B. Extend the range @p LR of
+  /// all predecessor values that reach this def. If @p LR is a subrange,
+  /// the array @p Undefs is the set of all locations where it is undefined
+  /// via <def,read-undef> in other subranges for the same register.
   void extendPHIRange(MachineBasicBlock &B, LiveRangeCalc &LRC,
-                      LiveRange &LR, ArrayRef<SlotIndex>);
+                      LiveRange &LR, LaneBitmask LM,
+                      ArrayRef<SlotIndex> Undefs);
 
   /// extendPHIKillRanges - Extend the ranges of all values killed by original
   /// parent PHIDefs.