[PATCH] D82916: LIS: fix handleMove to properly extend main range

[Stanislav Mekhanoshin via Phabricator via llvm-commits]

rampitec updated this revision to Diff 275817.
rampitec marked an inline comment as done.
rampitec added a comment.

Added comment.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D82916/new/

https://reviews.llvm.org/D82916

Files:
  llvm/lib/CodeGen/LiveIntervals.cpp
  llvm/unittests/MI/LiveIntervalTest.cpp


Index: llvm/unittests/MI/LiveIntervalTest.cpp
===================================================================
--- llvm/unittests/MI/LiveIntervalTest.cpp
+++ llvm/unittests/MI/LiveIntervalTest.cpp
@@ -499,6 +499,26 @@
   });
 }
 
+TEST(LiveIntervalTest, TestMoveSubRegUseAcrossMainRangeHole) {
+  liveIntervalTest(R"MIR(
+    %1:sgpr_128 = IMPLICIT_DEF
+  bb.1:
+    %2:sgpr_32 = COPY %1.sub2
+    %3:sgpr_32 = COPY %1.sub1
+    %1.sub2 = COPY %2
+    undef %1.sub0 = IMPLICIT_DEF
+    %1.sub2 = IMPLICIT_DEF
+    S_CBRANCH_SCC1 %bb.1, implicit undef $scc
+    S_BRANCH %bb.2
+  bb.2:
+)MIR", [](MachineFunction &MF, LiveIntervals &LIS) {
+    MachineInstr &MI = getMI(MF, 3, /*BlockNum=*/1);
+    MI.getOperand(0).setIsUndef(false);
+    testHandleMove(MF, LIS, 4, 3, 1);
+    testHandleMove(MF, LIS, 1, 4, 1);
+  });
+}
+
 TEST(LiveIntervalTest, BundleUse) {
   liveIntervalTest(R"MIR(
     %0 = IMPLICIT_DEF
Index: llvm/lib/CodeGen/LiveIntervals.cpp
===================================================================
--- llvm/lib/CodeGen/LiveIntervals.cpp
+++ llvm/lib/CodeGen/LiveIntervals.cpp
@@ -1011,6 +1011,20 @@
           }
         }
         updateRange(LI, Reg, LaneBitmask::getNone());
+        // If main range has a hole and we are moving a subrange use across
+        // the hole updateRange() cannot properly handle it since it only
+        // gets the LiveRange and not the whole LiveInterval. As a result
+        // we may end up with a main range not covering all subranges.
+        // This is extremely rare case, so let's check and reconstruct the
+        // main range.
+        for (LiveInterval::SubRange &S : LI.subranges()) {
+          if (LI.covers(S))
+            continue;
+          LI.clear();
+          LIS.constructMainRangeFromSubranges(LI);
+          break;
+        }
+
         continue;
       }
 


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