[PATCH] D49535: [RegisterCoalescer] Fixed inconsistent followCopyChain with subreg

[Tim Renouf via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rL338070: [RegisterCoalescer] Fixed inconsistent followCopyChain with subreg (authored by tpr, committed by ).

Repository:
  rL LLVM

https://reviews.llvm.org/D49535

Files:
  llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp


Index: llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp
===================================================================
--- llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp
+++ llvm/trunk/lib/CodeGen/RegisterCoalescer.cpp
@@ -2280,16 +2280,21 @@
       LiveQueryResult LRQ = LI.Query(Def);
       ValueIn = LRQ.valueIn();
     } else {
-      // Query subranges. Pick the first matching one.
+      // Query subranges. Ensure that all matching ones take us to the same def
+      // (allowing some of them to be undef).
       ValueIn = nullptr;
       for (const LiveInterval::SubRange &S : LI.subranges()) {
         // Transform lanemask to a mask in the joined live interval.
         LaneBitmask SMask = TRI->composeSubRegIndexLaneMask(SubIdx, S.LaneMask);
         if ((SMask & LaneMask).none())
           continue;
         LiveQueryResult LRQ = S.Query(Def);
-        ValueIn = LRQ.valueIn();
-        break;
+        if (!ValueIn) {
+          ValueIn = LRQ.valueIn();
+          continue;
+        }
+        if (LRQ.valueIn() && ValueIn != LRQ.valueIn())
+          return std::make_pair(VNI, TrackReg);
       }
     }
     if (ValueIn == nullptr) {


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