[llvm] r353038 - [NFC] Make a check in GuardWidening more obvious

[Philip Reames via llvm-commits]

Max,

I don't think this has exactly the effect you indended.  It doesn't 
break anything, but it does slow down the code.  The purpose of the 
original terminator check was to avoid doing the extra work when the 
guard was the terminator.

In fact, the whole find is overkill.  You should be able to use 
getIterator on the Instruction.

Would you mind making that simplification, and removing the isGuard 
check entirely?

Philip

On 2/4/19 2:41 AM, Max Kazantsev via llvm-commits wrote:
> Author: mkazantsev
> Date: Mon Feb  4 02:41:17 2019
> New Revision: 353038
>
> URL: http://llvm.org/viewvc/llvm-project?rev=353038&view=rev
> Log:
> [NFC] Make a check in GuardWidening more obvious
>
> Modified:
>      llvm/trunk/lib/Transforms/Scalar/GuardWidening.cpp
>
> Modified: llvm/trunk/lib/Transforms/Scalar/GuardWidening.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/GuardWidening.cpp?rev=353038&r1=353037&r2=353038&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Transforms/Scalar/GuardWidening.cpp (original)
> +++ llvm/trunk/lib/Transforms/Scalar/GuardWidening.cpp Mon Feb  4 02:41:17 2019
> @@ -375,7 +375,7 @@ bool GuardWideningImpl::eliminateInstrVi
>   
>       assert((i == (e - 1)) == (Instr->getParent() == CurBB) && "Bad DFS?");
>   
> -    if (Instr->getParent() == CurBB && CurBB->getTerminator() != Instr) {
> +    if (Instr->getParent() == CurBB && isGuard(Instr)) {
>         // Corner case: make sure we're only looking at guards strictly dominating
>         // GuardInst when visiting GuardInst->getParent().
>         auto NewEnd = std::find(I, E, Instr);
>
>
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