Commit 5366de73 authored by Arthur Eubanks's avatar Arthur Eubanks
Browse files

[SimpleLoopUnswitch] Don't non-trivially unswitch loops with catchswitch exits 

SplitBlock() can't handle catchswitch.

Fixes PR50973.

Reviewed By: aheejin

Differential Revision: https://reviews.llvm.org/D105672
parent 0e49c54a

llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp

+6 −5
Original line number Diff line number Diff line
@@ -2775,14 +2775,15 @@ static bool unswitchBestCondition( 
  SmallVector<BasicBlock *, 4> ExitBlocks;

  L.getUniqueExitBlocks(ExitBlocks);



  // We cannot unswitch if exit blocks contain a cleanuppad instruction as we

  // don't know how to split those exit blocks.

  // We cannot unswitch if exit blocks contain a cleanuppad/catchswitch

  // instruction as we don't know how to split those exit blocks.

  // FIXME: We should teach SplitBlock to handle this and remove this

  // restriction.

  for (auto *ExitBB : ExitBlocks) {

    if (isa<CleanupPadInst>(ExitBB->getFirstNonPHI())) {

      LLVM_DEBUG(

          dbgs() << "Cannot unswitch because of cleanuppad in exit block\n");

    auto *I = ExitBB->getFirstNonPHI();

    if (isa<CleanupPadInst>(I) || isa<CatchSwitchInst>(I)) {

      LLVM_DEBUG(dbgs() << "Cannot unswitch because of cleanuppad/catchswitch "

                           "in exit block\n");

      return false;

    }

  }

llvm/lib/Transforms/Utils/BasicBlockUtils.cpp

+3 −1
Original line number Diff line number Diff line
@@ -766,8 +766,10 @@ static BasicBlock *SplitBlockImpl(BasicBlock *Old, Instruction *SplitPt, 
                            BBName);

  }

  BasicBlock::iterator SplitIt = SplitPt->getIterator();

  while (isa<PHINode>(SplitIt) || SplitIt->isEHPad())

  while (isa<PHINode>(SplitIt) || SplitIt->isEHPad()) {

    ++SplitIt;

    assert(SplitIt != SplitPt->getParent()->end());

  }

  std::string Name = BBName.str();

  BasicBlock *New = Old->splitBasicBlock(

      SplitIt, Name.empty() ? Old->getName() + ".split" : Name);

llvm/test/Transforms/SimpleLoopUnswitch/catchswitch.ll

0 → 100644
+33 −0
Original line number Diff line number Diff line 
; RUN: opt -passes=simple-loop-unswitch -enable-nontrivial-unswitch < %s -S | FileCheck %s



; CHECK: if.end{{.*}}:

; CHECK-NOT: if.end{{.*}}:

declare i32 @__gxx_wasm_personality_v0(...)



declare void @foo()



define void @test(i1 %arg) personality i8* bitcast (i32 (...)* @__gxx_wasm_personality_v0 to i8*) {

entry:

  br label %while.body



while.body:                                       ; preds = %cleanup, %entry

  br i1 %arg, label %if.end, label %if.then



if.then:                                          ; preds = %while.body

  br label %if.end



if.end:                                           ; preds = %if.then, %while.body

  invoke void @foo()

          to label %cleanup unwind label %catch.dispatch



catch.dispatch:                                   ; preds = %invoke.cont, %if.end

  %0 = catchswitch within none [label %catch] unwind to caller



catch:                                            ; preds = %catch.dispatch

  %1 = catchpad within %0 [i8* null]

  unreachable



cleanup:                                          ; preds = %invoke.cont

  br label %while.body

}