Unverified Commit ca61e6a7 authored by Yingwei Zheng's avatar Yingwei Zheng Committed by GitHub
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Revert "[CVP] Check whether the default case is reachable (#79993)" (#81585) 

This reverts commit a034e65e.

Some protobuf users reported that this patch caused a significant
compile-time regression because `TailDuplicator` works poorly with a
specific pattern.

We will reland it once the codegen issue is fixed.
parent 44706bd4

llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp

+0 −34
Original line number Diff line number Diff line
@@ -371,7 +371,6 @@ static bool processSwitch(SwitchInst *I, LazyValueInfo *LVI, 
  { // Scope for SwitchInstProfUpdateWrapper. It must not live during

    // ConstantFoldTerminator() as the underlying SwitchInst can be changed.

    SwitchInstProfUpdateWrapper SI(*I);

    unsigned ReachableCaseCount = 0;



    for (auto CI = SI->case_begin(), CE = SI->case_end(); CI != CE;) {

      ConstantInt *Case = CI->getCaseValue();
@@ -408,33 +407,6 @@ static bool processSwitch(SwitchInst *I, LazyValueInfo *LVI, 


      // Increment the case iterator since we didn't delete it.

      ++CI;

      ++ReachableCaseCount;

    }



    BasicBlock *DefaultDest = SI->getDefaultDest();

    if (ReachableCaseCount > 1 &&

        !isa<UnreachableInst>(DefaultDest->getFirstNonPHIOrDbg())) {

      ConstantRange CR = LVI->getConstantRangeAtUse(I->getOperandUse(0),

                                                    /*UndefAllowed*/ false);

      // The default dest is unreachable if all cases are covered.

      if (!CR.isSizeLargerThan(ReachableCaseCount)) {

        BasicBlock *NewUnreachableBB =

            BasicBlock::Create(BB->getContext(), "default.unreachable",

                               BB->getParent(), DefaultDest);

        new UnreachableInst(BB->getContext(), NewUnreachableBB);



        DefaultDest->removePredecessor(BB);

        SI->setDefaultDest(NewUnreachableBB);



        if (SuccessorsCount[DefaultDest] == 1)

          DTU.applyUpdatesPermissive(

              {{DominatorTree::Delete, BB, DefaultDest}});

        DTU.applyUpdatesPermissive(

            {{DominatorTree::Insert, BB, NewUnreachableBB}});



        ++NumDeadCases;

        Changed = true;

      }

    }

  }
@@ -1255,12 +1227,6 @@ CorrelatedValuePropagationPass::run(Function &F, FunctionAnalysisManager &AM) { 
  if (!Changed) {

    PA = PreservedAnalyses::all();

  } else {

#if defined(EXPENSIVE_CHECKS)

    assert(DT->verify(DominatorTree::VerificationLevel::Full));

#else

    assert(DT->verify(DominatorTree::VerificationLevel::Fast));

#endif // EXPENSIVE_CHECKS



    PA.preserve<DominatorTreeAnalysis>();

    PA.preserve<LazyValueAnalysis>();

  }

llvm/test/Transforms/CorrelatedValuePropagation/basic.ll

+5 −6
Original line number Diff line number Diff line
@@ -442,7 +442,7 @@ define i32 @switch_range(i32 %cond) { 
; CHECK-NEXT:  entry:

; CHECK-NEXT:    [[S:%.*]] = urem i32 [[COND:%.*]], 3

; CHECK-NEXT:    [[S1:%.*]] = add nuw nsw i32 [[S]], 1

; CHECK-NEXT:    switch i32 [[S1]], label [[DEFAULT_UNREACHABLE:%.*]] [

; CHECK-NEXT:    switch i32 [[S1]], label [[UNREACHABLE:%.*]] [

; CHECK-NEXT:      i32 1, label [[EXIT1:%.*]]

; CHECK-NEXT:      i32 2, label [[EXIT2:%.*]]

; CHECK-NEXT:      i32 3, label [[EXIT1]]
@@ -451,8 +451,6 @@ define i32 @switch_range(i32 %cond) { 
; CHECK-NEXT:    ret i32 1

; CHECK:       exit2:

; CHECK-NEXT:    ret i32 2

; CHECK:       default.unreachable:

; CHECK-NEXT:    unreachable

; CHECK:       unreachable:

; CHECK-NEXT:    ret i32 0

;
@@ -515,9 +513,10 @@ define i8 @switch_defaultdest_multipleuse(i8 %t0) { 
; CHECK-NEXT:  entry:

; CHECK-NEXT:    [[O:%.*]] = or i8 [[T0:%.*]], 1

; CHECK-NEXT:    [[R:%.*]] = srem i8 1, [[O]]

; CHECK-NEXT:    br label [[EXIT:%.*]]

; CHECK:       default.unreachable:

; CHECK-NEXT:    unreachable

; CHECK-NEXT:    switch i8 [[R]], label [[EXIT:%.*]] [

; CHECK-NEXT:      i8 0, label [[EXIT]]

; CHECK-NEXT:      i8 1, label [[EXIT]]

; CHECK-NEXT:    ]

; CHECK:       exit:

; CHECK-NEXT:    ret i8 0

;

llvm/test/Transforms/CorrelatedValuePropagation/switch.ll

deleted100644 → 0
+0 −301
Original line number Diff line number Diff line 
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 4

; RUN: opt < %s -passes=correlated-propagation -S | FileCheck %s



define i32 @test_unreachable_default(i32 noundef %num) {

; CHECK-LABEL: define i32 @test_unreachable_default(

; CHECK-SAME: i32 noundef [[NUM:%.*]]) {

; CHECK-NEXT:  entry:

; CHECK-NEXT:    [[SUB:%.*]] = add i32 [[NUM]], -120

; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i32 [[SUB]], 3

; CHECK-NEXT:    [[COND:%.*]] = select i1 [[CMP]], i32 [[SUB]], i32 2

; CHECK-NEXT:    switch i32 [[COND]], label [[DEFAULT_UNREACHABLE:%.*]] [

; CHECK-NEXT:      i32 0, label [[SW_BB:%.*]]

; CHECK-NEXT:      i32 1, label [[SW_BB2:%.*]]

; CHECK-NEXT:      i32 2, label [[SW_BB4:%.*]]

; CHECK-NEXT:    ]

; CHECK:       sw.bb:

; CHECK-NEXT:    [[CALL:%.*]] = call i32 @call0()

; CHECK-NEXT:    br label [[CLEANUP:%.*]]

; CHECK:       sw.bb2:

; CHECK-NEXT:    [[CALL3:%.*]] = call i32 @call1()

; CHECK-NEXT:    br label [[CLEANUP]]

; CHECK:       sw.bb4:

; CHECK-NEXT:    [[CALL5:%.*]] = call i32 @call2()

; CHECK-NEXT:    br label [[CLEANUP]]

; CHECK:       default.unreachable:

; CHECK-NEXT:    unreachable

; CHECK:       sw.default:

; CHECK-NEXT:    [[CALL6:%.*]] = call i32 @call3()

; CHECK-NEXT:    br label [[CLEANUP]]

; CHECK:       cleanup:

; CHECK-NEXT:    [[RETVAL_0:%.*]] = phi i32 [ [[CALL6]], [[SW_DEFAULT:%.*]] ], [ [[CALL5]], [[SW_BB4]] ], [ [[CALL3]], [[SW_BB2]] ], [ [[CALL]], [[SW_BB]] ]

; CHECK-NEXT:    ret i32 [[RETVAL_0]]

;

entry:

  %sub = add i32 %num, -120

  %cmp = icmp ult i32 %sub, 3

  %cond = select i1 %cmp, i32 %sub, i32 2

  switch i32 %cond, label %sw.default [

  i32 0, label %sw.bb

  i32 1, label %sw.bb2

  i32 2, label %sw.bb4

  ]



sw.bb:

  %call = call i32 @call0()

  br label %cleanup



sw.bb2:

  %call3 = call i32 @call1()

  br label %cleanup



sw.bb4:

  %call5 = call i32 @call2()

  br label %cleanup



sw.default:

  %call6 = call i32 @call3()

  br label %cleanup



cleanup:

  %retval.0 = phi i32 [ %call6, %sw.default ], [ %call5, %sw.bb4 ], [ %call3, %sw.bb2 ], [ %call, %sw.bb ]

  ret i32 %retval.0

}



define i32 @test_unreachable_default_shared_edge(i32 noundef %num) {

; CHECK-LABEL: define i32 @test_unreachable_default_shared_edge(

; CHECK-SAME: i32 noundef [[NUM:%.*]]) {

; CHECK-NEXT:  entry:

; CHECK-NEXT:    [[SUB:%.*]] = add i32 [[NUM]], -120

; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i32 [[SUB]], 3

; CHECK-NEXT:    [[COND:%.*]] = select i1 [[CMP]], i32 [[SUB]], i32 2

; CHECK-NEXT:    switch i32 [[COND]], label [[DEFAULT_UNREACHABLE:%.*]] [

; CHECK-NEXT:      i32 0, label [[SW_BB:%.*]]

; CHECK-NEXT:      i32 1, label [[SW_BB2:%.*]]

; CHECK-NEXT:      i32 2, label [[SW_BB4:%.*]]

; CHECK-NEXT:    ]

; CHECK:       sw.bb:

; CHECK-NEXT:    [[CALL:%.*]] = call i32 @call0()

; CHECK-NEXT:    br label [[CLEANUP:%.*]]

; CHECK:       sw.bb2:

; CHECK-NEXT:    [[CALL3:%.*]] = call i32 @call1()

; CHECK-NEXT:    br label [[CLEANUP]]

; CHECK:       default.unreachable:

; CHECK-NEXT:    unreachable

; CHECK:       sw.bb4:

; CHECK-NEXT:    [[CALL5:%.*]] = call i32 @call4(i32 [[SUB]])

; CHECK-NEXT:    br label [[CLEANUP]]

; CHECK:       cleanup:

; CHECK-NEXT:    [[RETVAL_0:%.*]] = phi i32 [ [[CALL5]], [[SW_BB4]] ], [ [[CALL3]], [[SW_BB2]] ], [ [[CALL]], [[SW_BB]] ]

; CHECK-NEXT:    ret i32 [[RETVAL_0]]

;

entry:

  %sub = add i32 %num, -120

  %cmp = icmp ult i32 %sub, 3

  %cond = select i1 %cmp, i32 %sub, i32 2

  switch i32 %cond, label %sw.bb4 [

  i32 0, label %sw.bb

  i32 1, label %sw.bb2

  i32 2, label %sw.bb4

  ]



sw.bb:

  %call = call i32 @call0()

  br label %cleanup



sw.bb2:

  %call3 = call i32 @call1()

  br label %cleanup



sw.bb4:

  %val = phi i32 [ %sub, %entry ], [ %sub, %entry ]

  %call5 = call i32 @call4(i32 %val)

  br label %cleanup



cleanup:

  %retval.0 = phi i32 [ %call5, %sw.bb4 ], [ %call3, %sw.bb2 ], [ %call, %sw.bb ]

  ret i32 %retval.0

}



; Negative tests



define i32 @test_reachable_default(i32 noundef %num) {

; CHECK-LABEL: define i32 @test_reachable_default(

; CHECK-SAME: i32 noundef [[NUM:%.*]]) {

; CHECK-NEXT:  entry:

; CHECK-NEXT:    [[SUB:%.*]] = add i32 [[NUM]], -120

; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i32 [[SUB]], 3

; CHECK-NEXT:    [[COND:%.*]] = select i1 [[CMP]], i32 [[SUB]], i32 4

; CHECK-NEXT:    switch i32 [[COND]], label [[SW_DEFAULT:%.*]] [

; CHECK-NEXT:      i32 0, label [[SW_BB:%.*]]

; CHECK-NEXT:      i32 1, label [[SW_BB2:%.*]]

; CHECK-NEXT:      i32 2, label [[SW_BB4:%.*]]

; CHECK-NEXT:    ]

; CHECK:       sw.bb:

; CHECK-NEXT:    [[CALL:%.*]] = call i32 @call0()

; CHECK-NEXT:    br label [[CLEANUP:%.*]]

; CHECK:       sw.bb2:

; CHECK-NEXT:    [[CALL3:%.*]] = call i32 @call1()

; CHECK-NEXT:    br label [[CLEANUP]]

; CHECK:       sw.bb4:

; CHECK-NEXT:    [[CALL5:%.*]] = call i32 @call2()

; CHECK-NEXT:    br label [[CLEANUP]]

; CHECK:       sw.default:

; CHECK-NEXT:    [[CALL6:%.*]] = call i32 @call3()

; CHECK-NEXT:    br label [[CLEANUP]]

; CHECK:       cleanup:

; CHECK-NEXT:    [[RETVAL_0:%.*]] = phi i32 [ [[CALL6]], [[SW_DEFAULT]] ], [ [[CALL5]], [[SW_BB4]] ], [ [[CALL3]], [[SW_BB2]] ], [ [[CALL]], [[SW_BB]] ]

; CHECK-NEXT:    ret i32 [[RETVAL_0]]

;

entry:

  %sub = add i32 %num, -120

  %cmp = icmp ult i32 %sub, 3

  %cond = select i1 %cmp, i32 %sub, i32 4

  switch i32 %cond, label %sw.default [

  i32 0, label %sw.bb

  i32 1, label %sw.bb2

  i32 2, label %sw.bb4

  ]



sw.bb:

  %call = call i32 @call0()

  br label %cleanup



sw.bb2:

  %call3 = call i32 @call1()

  br label %cleanup



sw.bb4:

  %call5 = call i32 @call2()

  br label %cleanup



sw.default:

  %call6 = call i32 @call3()

  br label %cleanup



cleanup:

  %retval.0 = phi i32 [ %call6, %sw.default ], [ %call5, %sw.bb4 ], [ %call3, %sw.bb2 ], [ %call, %sw.bb ]

  ret i32 %retval.0

}



define i32 @test_unreachable_default_cond_may_be_undef(i32 %num) {

; CHECK-LABEL: define i32 @test_unreachable_default_cond_may_be_undef(

; CHECK-SAME: i32 [[NUM:%.*]]) {

; CHECK-NEXT:  entry:

; CHECK-NEXT:    [[SUB:%.*]] = add i32 [[NUM]], -120

; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i32 [[SUB]], 3

; CHECK-NEXT:    [[COND:%.*]] = select i1 [[CMP]], i32 [[SUB]], i32 2

; CHECK-NEXT:    switch i32 [[COND]], label [[SW_DEFAULT:%.*]] [

; CHECK-NEXT:      i32 0, label [[SW_BB:%.*]]

; CHECK-NEXT:      i32 1, label [[SW_BB2:%.*]]

; CHECK-NEXT:      i32 2, label [[SW_BB4:%.*]]

; CHECK-NEXT:    ]

; CHECK:       sw.bb:

; CHECK-NEXT:    [[CALL:%.*]] = call i32 @call0()

; CHECK-NEXT:    br label [[CLEANUP:%.*]]

; CHECK:       sw.bb2:

; CHECK-NEXT:    [[CALL3:%.*]] = call i32 @call1()

; CHECK-NEXT:    br label [[CLEANUP]]

; CHECK:       sw.bb4:

; CHECK-NEXT:    [[CALL5:%.*]] = call i32 @call2()

; CHECK-NEXT:    br label [[CLEANUP]]

; CHECK:       sw.default:

; CHECK-NEXT:    [[CALL6:%.*]] = call i32 @call3()

; CHECK-NEXT:    br label [[CLEANUP]]

; CHECK:       cleanup:

; CHECK-NEXT:    [[RETVAL_0:%.*]] = phi i32 [ [[CALL6]], [[SW_DEFAULT]] ], [ [[CALL5]], [[SW_BB4]] ], [ [[CALL3]], [[SW_BB2]] ], [ [[CALL]], [[SW_BB]] ]

; CHECK-NEXT:    ret i32 [[RETVAL_0]]

;

entry:

  %sub = add i32 %num, -120

  %cmp = icmp ult i32 %sub, 3

  %cond = select i1 %cmp, i32 %sub, i32 2

  switch i32 %cond, label %sw.default [

  i32 0, label %sw.bb

  i32 1, label %sw.bb2

  i32 2, label %sw.bb4

  ]



sw.bb:

  %call = call i32 @call0()

  br label %cleanup



sw.bb2:

  %call3 = call i32 @call1()

  br label %cleanup



sw.bb4:

  %call5 = call i32 @call2()

  br label %cleanup



sw.default:

  %call6 = call i32 @call3()

  br label %cleanup



cleanup:

  %retval.0 = phi i32 [ %call6, %sw.default ], [ %call5, %sw.bb4 ], [ %call3, %sw.bb2 ], [ %call, %sw.bb ]

  ret i32 %retval.0

}



define i32 @test_default_is_already_unreachable(i32 %num) {

; CHECK-LABEL: define i32 @test_default_is_already_unreachable(

; CHECK-SAME: i32 [[NUM:%.*]]) {

; CHECK-NEXT:  entry:

; CHECK-NEXT:    [[SUB:%.*]] = add i32 [[NUM]], -120

; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i32 [[SUB]], 3

; CHECK-NEXT:    [[COND:%.*]] = select i1 [[CMP]], i32 [[SUB]], i32 2

; CHECK-NEXT:    switch i32 [[COND]], label [[SW_DEFAULT:%.*]] [

; CHECK-NEXT:      i32 0, label [[SW_BB:%.*]]

; CHECK-NEXT:      i32 1, label [[SW_BB2:%.*]]

; CHECK-NEXT:      i32 2, label [[SW_BB4:%.*]]

; CHECK-NEXT:    ]

; CHECK:       sw.bb:

; CHECK-NEXT:    [[CALL:%.*]] = call i32 @call0()

; CHECK-NEXT:    br label [[CLEANUP:%.*]]

; CHECK:       sw.bb2:

; CHECK-NEXT:    [[CALL3:%.*]] = call i32 @call1()

; CHECK-NEXT:    br label [[CLEANUP]]

; CHECK:       sw.bb4:

; CHECK-NEXT:    [[CALL5:%.*]] = call i32 @call2()

; CHECK-NEXT:    br label [[CLEANUP]]

; CHECK:       sw.default:

; CHECK-NEXT:    unreachable

; CHECK:       cleanup:

; CHECK-NEXT:    [[RETVAL_0:%.*]] = phi i32 [ [[CALL5]], [[SW_BB4]] ], [ [[CALL3]], [[SW_BB2]] ], [ [[CALL]], [[SW_BB]] ]

; CHECK-NEXT:    ret i32 [[RETVAL_0]]

;

entry:

  %sub = add i32 %num, -120

  %cmp = icmp ult i32 %sub, 3

  %cond = select i1 %cmp, i32 %sub, i32 2

  switch i32 %cond, label %sw.default [

  i32 0, label %sw.bb

  i32 1, label %sw.bb2

  i32 2, label %sw.bb4

  ]



sw.bb:

  %call = call i32 @call0()

  br label %cleanup



sw.bb2:

  %call3 = call i32 @call1()

  br label %cleanup



sw.bb4:

  %call5 = call i32 @call2()

  br label %cleanup



sw.default:

  unreachable



cleanup:

  %retval.0 = phi i32 [ %call5, %sw.bb4 ], [ %call3, %sw.bb2 ], [ %call, %sw.bb ]

  ret i32 %retval.0

}



declare i32 @call0()

declare i32 @call1()

declare i32 @call2()

declare i32 @call3()

declare i32 @call4(i32)