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[LoopSimplifyCFG] Use DTU.applyUpdates instead of insert/deleteEdge
`insert/deleteEdge` methods in DTU can make updates incorrectly in some cases (see https://bugs.llvm.org/show_bug.cgi?id=40528), and it is recommended to use `applyUpdates` methods instead when it is needed to make a mass update in CFG. Differential Revision: https://reviews.llvm.org/D57316 Reviewed By: kuhar llvm-svn: 353502
This commit is contained in:
Max Kazantsev
parent
81bbef609c
commit
eed2a938a5
@ -89,6 +89,8 @@ private:
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DominatorTree &DT;
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ScalarEvolution &SE;
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MemorySSAUpdater *MSSAU;
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DomTreeUpdater DTU;
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SmallVector<DominatorTree::UpdateType, 16> DTUpdates;
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// Whether or not the current loop has irreducible CFG.
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bool HasIrreducibleCFG = false;
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@ -319,14 +321,13 @@ private:
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// Construct split preheader and the dummy switch to thread edges from it to
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// dead exits.
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DomTreeUpdater DTU(DT, DomTreeUpdater::UpdateStrategy::Eager);
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BasicBlock *Preheader = L.getLoopPreheader();
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BasicBlock *NewPreheader = Preheader->splitBasicBlock(
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Preheader->getTerminator(),
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Twine(Preheader->getName()).concat("-split"));
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DTU.deleteEdge(Preheader, L.getHeader());
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DTU.insertEdge(NewPreheader, L.getHeader());
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DTU.insertEdge(Preheader, NewPreheader);
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DTUpdates.push_back({DominatorTree::Delete, Preheader, L.getHeader()});
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DTUpdates.push_back({DominatorTree::Insert, NewPreheader, L.getHeader()});
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DTUpdates.push_back({DominatorTree::Insert, Preheader, NewPreheader});
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IRBuilder<> Builder(Preheader->getTerminator());
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SwitchInst *DummySwitch =
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Builder.CreateSwitch(Builder.getInt32(0), NewPreheader);
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@ -345,7 +346,7 @@ private:
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}
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assert(DummyIdx != 0 && "Too many dead exits!");
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DummySwitch->addCase(Builder.getInt32(DummyIdx++), BB);
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DTU.insertEdge(Preheader, BB);
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DTUpdates.push_back({DominatorTree::Insert, Preheader, BB});
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++NumLoopExitsDeleted;
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}
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@ -389,6 +390,9 @@ private:
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while (FixLCSSALoop->getParentLoop() != StillReachable)
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FixLCSSALoop = FixLCSSALoop->getParentLoop();
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assert(FixLCSSALoop && "Should be a loop!");
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// We need all DT updates to be done before forming LCSSA.
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DTU.applyUpdates(DTUpdates);
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DTUpdates.clear();
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formLCSSARecursively(*FixLCSSALoop, DT, &LI, &SE);
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}
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}
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@ -397,7 +401,6 @@ private:
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/// Delete loop blocks that have become unreachable after folding. Make all
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/// relevant updates to DT and LI.
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void deleteDeadLoopBlocks() {
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DomTreeUpdater DTU(DT, DomTreeUpdater::UpdateStrategy::Eager);
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if (MSSAU) {
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SmallPtrSet<BasicBlock *, 8> DeadLoopBlocksSet(DeadLoopBlocks.begin(),
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DeadLoopBlocks.end());
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@ -415,15 +418,18 @@ private:
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LI.removeBlock(BB);
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}
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DeleteDeadBlocks(DeadLoopBlocks, &DTU);
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DetatchDeadBlocks(DeadLoopBlocks, &DTUpdates);
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DTU.applyUpdates(DTUpdates);
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DTUpdates.clear();
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for (auto *BB : DeadLoopBlocks)
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BB->eraseFromParent();
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NumLoopBlocksDeleted += DeadLoopBlocks.size();
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}
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/// Constant-fold terminators of blocks acculumated in FoldCandidates into the
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/// unconditional branches.
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void foldTerminators() {
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DomTreeUpdater DTU(DT, DomTreeUpdater::UpdateStrategy::Eager);
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for (BasicBlock *BB : FoldCandidates) {
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assert(LI.getLoopFor(BB) == &L && "Should be a loop block!");
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BasicBlock *TheOnlySucc = getOnlyLiveSuccessor(BB);
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@ -465,7 +471,7 @@ private:
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Term->eraseFromParent();
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for (auto *DeadSucc : DeadSuccessors)
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DTU.deleteEdge(BB, DeadSucc);
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DTUpdates.push_back({DominatorTree::Delete, BB, DeadSucc});
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++NumTerminatorsFolded;
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}
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@ -475,7 +481,8 @@ public:
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ConstantTerminatorFoldingImpl(Loop &L, LoopInfo &LI, DominatorTree &DT,
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ScalarEvolution &SE,
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MemorySSAUpdater *MSSAU)
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: L(L), LI(LI), DT(DT), SE(SE), MSSAU(MSSAU) {}
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: L(L), LI(LI), DT(DT), SE(SE), MSSAU(MSSAU),
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DTU(DT, DomTreeUpdater::UpdateStrategy::Eager) {}
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bool run() {
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assert(L.getLoopLatch() && "Should be single latch!");
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@ -539,6 +546,10 @@ public:
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<< " dead blocks in loop " << L.getHeader()->getName()
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<< "\n");
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deleteDeadLoopBlocks();
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} else {
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// If we didn't do updates inside deleteDeadLoopBlocks, do them here.
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DTU.applyUpdates(DTUpdates);
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DTUpdates.clear();
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}
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#ifndef NDEBUG
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@ -1,5 +1,4 @@
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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; XFAIL: *
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; REQUIRES: asserts
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; RUN: opt -S -enable-loop-simplifycfg-term-folding=true -loop-simplifycfg -debug-only=loop-simplifycfg -verify-loop-info -verify-dom-info -verify-loop-lcssa 2>&1 < %s | FileCheck %s
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; RUN: opt -S -enable-loop-simplifycfg-term-folding=true -passes='require<domtree>,loop(simplify-cfg)' -debug-only=loop-simplifycfg -verify-loop-info -verify-dom-info -verify-loop-lcssa 2>&1 < %s | FileCheck %s
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@ -2582,6 +2581,84 @@ exit:
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}
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define void @test_crash_01() {
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; CHECK-LABEL: @test_crash_01(
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; CHECK-NEXT: bb:
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; CHECK-NEXT: br label [[BB1:%.*]]
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; CHECK: bb1:
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; CHECK-NEXT: br i1 undef, label [[BB17:%.*]], label [[BB2:%.*]]
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; CHECK: bb2:
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; CHECK-NEXT: switch i32 0, label [[BB2_SPLIT:%.*]] [
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; CHECK-NEXT: i32 1, label [[BB19:%.*]]
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; CHECK-NEXT: ]
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; CHECK: bb2-split:
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; CHECK-NEXT: br label [[BB3:%.*]]
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; CHECK: bb3:
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; CHECK-NEXT: switch i32 undef, label [[BB16:%.*]] [
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; CHECK-NEXT: i32 0, label [[BB15:%.*]]
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; CHECK-NEXT: i32 1, label [[BB14:%.*]]
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; CHECK-NEXT: i32 2, label [[BB13:%.*]]
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; CHECK-NEXT: i32 3, label [[BB12:%.*]]
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; CHECK-NEXT: i32 4, label [[BB11:%.*]]
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; CHECK-NEXT: i32 5, label [[BB8:%.*]]
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; CHECK-NEXT: i32 6, label [[BB10:%.*]]
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; CHECK-NEXT: i32 7, label [[BB9:%.*]]
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; CHECK-NEXT: i32 8, label [[BB7:%.*]]
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; CHECK-NEXT: ]
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; CHECK: bb7:
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; CHECK-NEXT: unreachable
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; CHECK: bb8:
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; CHECK-NEXT: switch i32 undef, label [[BB28:%.*]] [
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; CHECK-NEXT: i32 0, label [[BB27:%.*]]
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; CHECK-NEXT: i32 1, label [[BB26:%.*]]
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; CHECK-NEXT: i32 2, label [[BB23:%.*]]
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; CHECK-NEXT: i32 3, label [[BB24:%.*]]
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; CHECK-NEXT: i32 4, label [[BB25:%.*]]
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; CHECK-NEXT: i32 5, label [[BB29:%.*]]
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; CHECK-NEXT: i32 6, label [[BB22:%.*]]
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; CHECK-NEXT: i32 7, label [[BB20:%.*]]
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; CHECK-NEXT: i32 8, label [[BB21:%.*]]
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; CHECK-NEXT: ]
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; CHECK: bb9:
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; CHECK-NEXT: unreachable
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; CHECK: bb10:
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; CHECK-NEXT: unreachable
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; CHECK: bb11:
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; CHECK-NEXT: br label [[BB8]]
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; CHECK: bb12:
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; CHECK-NEXT: unreachable
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; CHECK: bb13:
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; CHECK-NEXT: unreachable
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; CHECK: bb14:
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; CHECK-NEXT: unreachable
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; CHECK: bb15:
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; CHECK-NEXT: unreachable
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; CHECK: bb16:
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; CHECK-NEXT: unreachable
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; CHECK: bb17:
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; CHECK-NEXT: ret void
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; CHECK: bb19:
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; CHECK-NEXT: ret void
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; CHECK: bb20:
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; CHECK-NEXT: unreachable
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; CHECK: bb21:
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; CHECK-NEXT: unreachable
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; CHECK: bb22:
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; CHECK-NEXT: unreachable
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; CHECK: bb23:
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; CHECK-NEXT: unreachable
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; CHECK: bb24:
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; CHECK-NEXT: unreachable
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; CHECK: bb25:
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; CHECK-NEXT: unreachable
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; CHECK: bb26:
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; CHECK-NEXT: unreachable
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; CHECK: bb27:
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; CHECK-NEXT: unreachable
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; CHECK: bb28:
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; CHECK-NEXT: unreachable
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; CHECK: bb29:
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; CHECK-NEXT: br label [[BB3]]
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;
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bb:
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br label %bb1
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