[cfe-dev] [llvm-dev] [4.0.0 Release] 'final' has been tagged

[Khem Raj via cfe-dev]

Hi Hans

On 3/10/17 1:10 PM, Hans Wennborg wrote:
> Hi Khem,
> 
> On Fri, Mar 10, 2017 at 1:03 PM, Khem Raj via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
>> On Fri, Mar 10, 2017 at 7:01 AM, Renato Golin via llvm-dev
>> <llvm-dev at lists.llvm.org> wrote:
>>> ARM and AArch64 looking good, uploaded.
>>>
>>
>> This is not particularly related to this RC but in general with 4.0.0
>> I am seeing a failure quite common while building for arm
>>
>> | ./.libs/libsqlite3.so: undefined reference to `__mulodi4'
>> | clang-4.0: error: linker command failed with exit code 1 (use -v to
>> see invocation)
>> | make: *** [Makefile:509: sqlite3] Error 1
>>
>> There are few bug reports in bugzilla also reporting similar issue
>> e.g.
>>
>> https://bugs.llvm.org//show_bug.cgi?id=14469
> 
> Many of those bugs are pre-4.0.0. Did you see the same issues with
> earlier LLVM versions as well, or are you saying these errors are new
> with 4.0.0?
> 

I dug into a bit and here is a reproducer

#include <stddef.h>
size_t n;
size_t s;
ptrdiff_t z;
main()
{
    return __builtin_mul_overflow(n,s, &z);
}

compiling with
clang --target=armv7l -mfloat-abi=hard hello.c -S

This generates the call to __mulodi4

same code with gcc does not.

I see that sqlite3 as well as m4 package pokes the compiler for these
builtins before using them. For clang it uses __has_builtin() to
determine if a given builtin is supported before using it.

see
http://git.savannah.gnu.org/cgit/gnulib.git/tree/lib/xalloc-oversized.h

That is the source of trouble, since its in gnulib that explains why its
showing up in lot of packages.

perhaps this commit here
http://git.savannah.gnu.org/cgit/gnulib.git/commit/lib/xalloc-oversized.h?id=9c919a06435266a88d91ffb9eb3f70a82aa65b4b

brings this issue to fore.


> Thanks,
> Hans
> 

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