[llvm] r258654 - [SCCP] Remove duplicate code

[NAKAMURA Takumi via llvm-commits]

It crashes LTO.
http://bb.pgr.jp/builders/clang-3stage-x86_64-linux/builds/9251

A reduced testcase attached. Reproducible with "opt -ipsccp".

On Sun, Jan 24, 2016 at 3:30 PM David Majnemer via llvm-commits <
llvm-commits at lists.llvm.org> wrote:

> Author: majnemer
> Date: Sun Jan 24 00:26:47 2016
> New Revision: 258654
>
> URL: http://llvm.org/viewvc/llvm-project?rev=258654&view=rev
> Log:
> [SCCP] Remove duplicate code
>
> SCCP has code identical to changeToUnreachable's behavior, switch it
> over to just call changeToUnreachable.
>
> No functionality change intended.
>
> Modified:
>     llvm/trunk/include/llvm/Transforms/Utils/Local.h
>     llvm/trunk/lib/Transforms/Scalar/SCCP.cpp
>     llvm/trunk/lib/Transforms/Utils/Local.cpp
>
> Modified: llvm/trunk/include/llvm/Transforms/Utils/Local.h
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/Utils/Local.h?rev=258654&r1=258653&r2=258654&view=diff
>
> ==============================================================================
> --- llvm/trunk/include/llvm/Transforms/Utils/Local.h (original)
> +++ llvm/trunk/include/llvm/Transforms/Utils/Local.h Sun Jan 24 00:26:47
> 2016
> @@ -295,7 +295,7 @@ unsigned removeAllNonTerminatorAndEHPadI
>
>  /// \brief Insert an unreachable instruction before the specified
>  /// instruction, making it and the rest of the code in the block dead.
> -void changeToUnreachable(Instruction *I, bool UseLLVMTrap);
> +unsigned changeToUnreachable(Instruction *I, bool UseLLVMTrap);
>
>  /// Replace 'BB's terminator with one that does not have an unwind
> successor
>  /// block.  Rewrites `invoke` to `call`, etc.  Updates any PHIs in unwind
>
> Modified: llvm/trunk/lib/Transforms/Scalar/SCCP.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/SCCP.cpp?rev=258654&r1=258653&r2=258654&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/Transforms/Scalar/SCCP.cpp (original)
> +++ llvm/trunk/lib/Transforms/Scalar/SCCP.cpp Sun Jan 24 00:26:47 2016
> @@ -1564,14 +1564,6 @@ FunctionPass *llvm::createSCCPPass() {
>    return new SCCP();
>  }
>
> -static void DeleteInstructionInBlock(BasicBlock *BB) {
> -  DEBUG(dbgs() << "  BasicBlock Dead:" << *BB);
> -  ++NumDeadBlocks;
> -
> -  unsigned NumRemovedInBB =
> removeAllNonTerminatorAndEHPadInstructions(BB);
> -  NumInstRemoved += NumRemovedInBB;
> -}
> -
>  // runOnFunction() - Run the Sparse Conditional Constant Propagation
> algorithm,
>  // and return true if the function was modified.
>  //
> @@ -1608,7 +1600,11 @@ bool SCCP::runOnFunction(Function &F) {
>
>    for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
>      if (!Solver.isBlockExecutable(&*BB)) {
> -      DeleteInstructionInBlock(&*BB);
> +      DEBUG(dbgs() << "  BasicBlock Dead:" << *BB);
> +
> +      ++NumDeadBlocks;
> +      NumInstRemoved += removeAllNonTerminatorAndEHPadInstructions(BB);
> +
>        MadeChanges = true;
>        continue;
>      }
> @@ -1806,18 +1802,13 @@ bool IPSCCP::runOnModule(Module &M) {
>
>      for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
> {
>        if (!Solver.isBlockExecutable(&*BB)) {
> -        DeleteInstructionInBlock(&*BB);
> -        MadeChanges = true;
> +        DEBUG(dbgs() << "  BasicBlock Dead:" << *BB);
>
> -        TerminatorInst *TI = BB->getTerminator();
> -        for (BasicBlock *Succ : TI->successors()) {
> -          if (!Succ->empty() && isa<PHINode>(Succ->begin()))
> -            Succ->removePredecessor(&*BB);
> -        }
> -        if (!TI->use_empty())
> -          TI->replaceAllUsesWith(UndefValue::get(TI->getType()));
> -        TI->eraseFromParent();
> -        new UnreachableInst(M.getContext(), &*BB);
> +        ++NumDeadBlocks;
> +        NumInstRemoved +=
> +            changeToUnreachable(&*BB->begin(), /*UseLLVMTrap=*/false);
> +
> +        MadeChanges = true;
>
>          if (&*BB != &F->front())
>            BlocksToErase.push_back(&*BB);
>
> Modified: llvm/trunk/lib/Transforms/Utils/Local.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/Local.cpp?rev=258654&r1=258653&r2=258654&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/Transforms/Utils/Local.cpp (original)
> +++ llvm/trunk/lib/Transforms/Utils/Local.cpp Sun Jan 24 00:26:47 2016
> @@ -1243,7 +1243,7 @@ unsigned llvm::removeAllNonTerminatorAnd
>    return NumDeadInst;
>  }
>
> -void llvm::changeToUnreachable(Instruction *I, bool UseLLVMTrap) {
> +unsigned llvm::changeToUnreachable(Instruction *I, bool UseLLVMTrap) {
>    BasicBlock *BB = I->getParent();
>    // Loop over all of the successors, removing BB's entry from any PHI
>    // nodes.
> @@ -1261,12 +1261,15 @@ void llvm::changeToUnreachable(Instructi
>    new UnreachableInst(I->getContext(), I);
>
>    // All instructions after this are dead.
> +  unsigned NumInstrsRemoved = 0;
>    BasicBlock::iterator BBI = I->getIterator(), BBE = BB->end();
>    while (BBI != BBE) {
>      if (!BBI->use_empty())
>        BBI->replaceAllUsesWith(UndefValue::get(BBI->getType()));
>      BB->getInstList().erase(BBI++);
> +    ++NumInstrsRemoved;
>    }
> +  return NumInstrsRemoved;
>  }
>
>  /// changeToCall - Convert the specified invoke into a normal call.
>
>
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