[SimpleLoopUnswitch] Clear dispos in deleteDeadBlocksFromLoop.

SimpleLoopUnswitch may remove blocks from loops. Clear block and loop dispositions in that case, to clean up invalid entries in the cache. Fixes #58158. Fixes #58159.
llvm · Oct 5, 2022 · 469f0fc · 469f0fc
1 parent eb975ca
commit 469f0fc
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diff --git a/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp b/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp
@@ -1620,6 +1620,7 @@ deleteDeadBlocksFromLoop(Loop &L,
                          SmallVectorImpl<BasicBlock *> &ExitBlocks,
                          DominatorTree &DT, LoopInfo &LI,
                          MemorySSAUpdater *MSSAU,
+                         ScalarEvolution *SE,
                          function_ref<void(Loop &, StringRef)> DestroyLoopCB) {
   // Find all the dead blocks tied to this loop, and remove them from their
   // successors.
@@ -1671,6 +1672,8 @@ deleteDeadBlocksFromLoop(Loop &L,
            "If the child loop header is dead all blocks in the child loop must "
            "be dead as well!");
     DestroyLoopCB(*ChildL, ChildL->getName());
+    if (SE)
+      SE->forgetBlockAndLoopDispositions();
     LI.destroy(ChildL);
     return true;
   });
@@ -2377,7 +2380,7 @@ static void unswitchNontrivialInvariants(
   // Now that our cloned loops have been built, we can update the original loop.
   // First we delete the dead blocks from it and then we rebuild the loop
   // structure taking these deletions into account.
-  deleteDeadBlocksFromLoop(L, ExitBlocks, DT, LI, MSSAU, DestroyLoopCB);
+  deleteDeadBlocksFromLoop(L, ExitBlocks, DT, LI, MSSAU, SE,DestroyLoopCB);
 
   if (MSSAU && VerifyMemorySSA)
     MSSAU->getMemorySSA()->verifyMemorySSA();

diff --git a/llvm/test/Transforms/SimpleLoopUnswitch/invalidate-block-and-loop-dispositions.ll b/llvm/test/Transforms/SimpleLoopUnswitch/invalidate-block-and-loop-dispositions.ll
@@ -71,3 +71,42 @@ exit:                                             ; preds = %then.bb, %loop.head
 }
 
 declare i16 @foo() nounwind readnone
+
+define void @test_pr58158(i1 %c.1) {
+; CHECK-LABEL: @test_pr58158(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[CALL:%.*]] = tail call i16 @bar()
+; CHECK-NEXT:    br i1 [[C_1:%.*]], label [[ENTRY_SPLIT_US:%.*]], label [[ENTRY_SPLIT:%.*]]
+; CHECK:       entry.split.us:
+; CHECK-NEXT:    br label [[OUTER_US:%.*]]
+; CHECK:       outer.us:
+; CHECK-NEXT:    br label [[INNER_PREHEADER_US:%.*]]
+; CHECK:       inner.us:
+; CHECK-NEXT:    [[C_2_US:%.*]] = icmp eq i16 0, [[CALL]]
+; CHECK-NEXT:    br i1 [[C_2_US]], label [[OUTER_LOOPEXIT_US:%.*]], label [[INNER_US:%.*]]
+; CHECK:       inner.preheader.us:
+; CHECK-NEXT:    br label [[INNER_US]]
+; CHECK:       outer.loopexit.us:
+; CHECK-NEXT:    br label [[OUTER_BACKEDGE_US:%.*]]
+; CHECK:       outer.backedge.us:
+; CHECK-NEXT:    br label [[OUTER_US]]
+; CHECK:       entry.split:
+; CHECK-NEXT:    br label [[OUTER:%.*]]
+; CHECK:       outer:
+; CHECK-NEXT:    br label [[OUTER_BACKEDGE:%.*]]
+; CHECK:       outer.backedge:
+; CHECK-NEXT:    br label [[OUTER]]
+;
+entry:
+  %call = tail call i16 @bar()
+  br label %outer
+
+outer:
+  br i1 %c.1, label %inner, label %outer
+
+inner:
+  %c.2 = icmp eq i16 0, %call
+  br i1 %c.2, label %outer, label %inner
+}
+
+declare i16 @bar()