[llvm-dev] (Thin)LTO llvm build

[Mehdi Amini via llvm-dev]

> On Sep 16, 2016, at 1:48 PM, Carsten Mattner via llvm-dev <llvm-dev at lists.llvm.org> wrote:
> 
> On Fri, Sep 16, 2016 at 10:18 PM, Teresa Johnson <tejohnson at google.com> wrote:
>> 
>> Cc'ing llvm-dev again in case someone knows what is going on.
>> 
>> That error is coming from a polly configure script, which I don't
>> have cloned into my own tree. Not sure why polly would behave
>> differently when configuring for ThinLTO. Does polly configure ok
>> when configuring the same way, but for regular LTO?
> 
> Yes it does, and I don't remember when I've added it, meaning it's
> been working when bootstrapping llvm with the host gcc toolchain, for
> a long time.
> 

Can you look for the specific errors in the CMake log and error files?

CMake is very good at not presenting the real issue…
Here it is trying to build very simple programs to check features availability. Like:

   #include <strings.h>
   int main() { ffs(0); return 0; }


— 
Mehdi



>> On Fri, Sep 16, 2016 at 12:36 PM, Carsten Mattner <carstenmattner at gmail.com> wrote:
>>> 
>>> Hi Teresa,
>>> 
>>> I've just attempted a THIN_LTO build again, and the
>>> error I ran into is as follows, and happens during
>>> cmake. I'm explicitly telling cmake to us llvm-ar and llvm-ranlib
>>> as suggested.
>>> 
>>> [...]
>>> -- Performing Test COMPILER_RT_HAS_STATIC_FLAG - Success
>>> -- Performing Test COMPILER_RT_SUPPORTS_ATOMIC_KEYWORD
>>> -- Performing Test COMPILER_RT_SUPPORTS_ATOMIC_KEYWORD - Success
>>> -- Builtin supported architectures:
>>> -- ISL version: isl-0.17.1-164-gcbba1b6
>>> -- Performing Test HAS_ATTRIBUTE_WARN_UNUSED_RESULT
>>> -- Performing Test HAS_ATTRIBUTE_WARN_UNUSED_RESULT - Failed
>>> -- Performing Test HAVE___ATTRIBUTE__
>>> -- Performing Test HAVE___ATTRIBUTE__ - Failed
>>> -- Performing Test HAVE_DECL_FFS
>>> -- Performing Test HAVE_DECL_FFS - Failed
>>> -- Performing Test HAVE_DECL___BUILTIN_FFS
>>> -- Performing Test HAVE_DECL___BUILTIN_FFS - Failed
>>> -- Performing Test HAVE_DECL__BITSCANFORWARD
>>> -- Performing Test HAVE_DECL__BITSCANFORWARD - Failed
>>> CMake Error at tools/polly/lib/External/CMakeLists.txt:90 (message):
>>>  No ffs implementation found
>>> [...]
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