[llvm-commits] [llvm] r164934 - in /llvm/trunk: lib/Transforms/Utils/SimplifyCFG.cpp test/Transforms/SimplifyCFG/switch_to_lookup_table.ll

[Benjamin Kramer]

On 03.10.2012, at 12:41, Hans Wennborg <hans at chromium.org> wrote:

> On Mon, Oct 1, 2012 at 12:31 PM, Benjamin Kramer
> <benny.kra at googlemail.com> wrote:
>> Author: d0k
>> Date: Mon Oct  1 06:31:48 2012
>> New Revision: 164934
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=164934&view=rev
>> Log:
>> SimplifyCFG: Don't crash when forming a switch bitmap with an undef default value.
>> 
>> Fixes PR13985.
> 
> Thanks for fixing!
> 
> Could there be other cases where a Constant with Integer type does not
> turn out to be a ConstantInt?


Looking at ValidLookupTableConstant:
>   if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C))
>     return CE->isGEPWithNoNotionalOverIndexing();
> 
>   return isa<ConstantFP>(C) ||
>       isa<ConstantInt>(C) ||
>       isa<ConstantPointerNull>(C) ||
>       isa<GlobalValue>(C) ||
>       isa<UndefValue>(C);

GEP constantexprs, ConstantPointerNull and GlobalValues always have pointer type, leaving only ConstantFP (which is always FP), UndefValue (which can be anything) and ConstantInt. I think handling ConstantInt and UndefValue is sufficient.

- Ben