[PATCH] D30428: [AMDGPU] Fix read-undef flags when schedule is reverted

[Stanislav Mekhanoshin via Phabricator via llvm-commits]

rampitec created this revision.
Herald added subscribers: tpr, dstuttard, tony-tye, yaxunl, nhaehnle, wdng, kzhuravl, arsenm.

If two subregs of the same register are defined and we need to revert
schedule changing def order, we will end up with both instructions
having def,read-undef flags because adjustLaneLiveness() will only set
this flag but will not remove it.

Fix this by removing read-undef flags before calling adjustLaneLiveness.


Repository:
  rL LLVM

https://reviews.llvm.org/D30428

Files:
  lib/Target/AMDGPU/GCNSchedStrategy.cpp


Index: lib/Target/AMDGPU/GCNSchedStrategy.cpp
===================================================================
--- lib/Target/AMDGPU/GCNSchedStrategy.cpp
+++ lib/Target/AMDGPU/GCNSchedStrategy.cpp
@@ -350,6 +350,9 @@
       BB->insert(RegionEnd, MI);
       if (LIS) {
         LIS->handleMove(*MI, true);
+        // Reset read-undef flags and update them later.
+        for (auto &Def : MI->defs())
+          Def.setIsUndef(false);
         RegisterOperands RegOpers;
         RegOpers.collect(*MI, *TRI, MRI, ShouldTrackLaneMasks, false);
         if (ShouldTrackLaneMasks) {


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