[PATCH] D128553: [LiveIntervals] Fix incorrect range (re)construction from subranges.

[Daniil Fukalov via Phabricator via llvm-commits]

dfukalov created this revision.
dfukalov added reviewers: rampitec, arsenm, qcolombet, MatzeB.
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After D82916 <https://reviews.llvm.org/D82916> `updateAllRanges()` started to fix holes in main range with
subranges but it fails on instructions with two subregs def which are parts of
one reg. The main range constructed with //all// subranges of subregs just after
processing the first operand. So the main range gets intervals from subranges
those are not updated yet.

The patch takes into account lane mask to update the main range.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D128553

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
@@ -532,6 +532,19 @@
   });
 }
 
+TEST(LiveIntervalTest, TestMoveSubRegsOfOneReg) {
+  liveIntervalTest(R"MIR(
+    INLINEASM &"", 0, 1835018, def undef %4.sub0:vreg_64, 1835018, def undef %4.sub1:vreg_64
+    %1:vreg_64 = COPY %4
+    undef %2.sub0:vreg_64 = V_MOV_B32_e32 0, implicit $exec
+    %2.sub1:vreg_64 = COPY %2.sub0
+    %3:vreg_64 = COPY %2
+)MIR", [](MachineFunction &MF, LiveIntervals &LIS) {
+    testHandleMove(MF, LIS, 1, 4);
+    testHandleMove(MF, LIS, 0, 3);
+  });
+}
+
 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
@@ -1049,12 +1049,17 @@
         // 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;
+        if (LI.hasSubRanges()) {
+          unsigned SubReg = MO.getSubReg();
+          LaneBitmask LaneMask = SubReg ? TRI.getSubRegIndexLaneMask(SubReg)
+                                        : MRI.getMaxLaneMaskForVReg(Reg);
+          for (LiveInterval::SubRange &S : LI.subranges()) {
+            if ((S.LaneMask & LaneMask).none() || LI.covers(S))
+              continue;
+            LI.clear();
+            LIS.constructMainRangeFromSubranges(LI);
+            break;
+          }
         }
 
         continue;


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