Re: Test with an lto-build of libgfortran.

[Jeff Law <jeffreyalaw@gmail.com>]

On 9/27/23 12:21, Toon Moene wrote:

> 
> The lto-ing of libgfortran did succeed, because I did get a new warning:
> 
> gfortran -O3 -flto -flto-partition=none -static  -o xlintstrfz zchkrfp.o 
> zdrvrfp.o zdrvrf1.o zdrvrf2.o zdrvrf3.o zdrvrf4.o zerrrfp.o zlatb4.o 
> zlaipd.o zlarhs.o zsbmv.o zget04.o zpot01.o zpot03.o zpot02.o chkxer.o 
> xerbla.o alaerh.o aladhd.o alahd.o alasvm.o ../../libtmglib.a 
> ../../liblapack.a ../../librefblas.a
> In function 'xtoa_big',
>      inlined from 'write_z' at 
> /home/toon/compilers/gcc/libgfortran/io/write.c:1296:11,
>      inlined from 'formatted_transfer_scalar_write' at 
> /home/toon/compilers/gcc/libgfortran/io/transfer.c:2136:4:
> /home/toon/compilers/gcc/libgfortran/io/write.c:1222:6: warning: writing 
> 1 byte into a region of size 0 [-Wstringop-overflow=]
>   1222 |   *q = '\0';
>        |      ^
> /home/toon/compilers/gcc/libgfortran/io/write.c: In function 
> 'formatted_transfer_scalar_write':
> /home/toon/compilers/gcc/libgfortran/io/write.c:1291:8: note: at offset 
> [34, 4294967294] into destination object 'itoa_buf' of size 33
>   1291 |   char itoa_buf[GFC_XTOA_BUF_SIZE];
>        |        ^
> 
> which was (of course) not given with a non-lto libgfortran.
Yea.  This certainly can happen with LTO.  These warnings would 
definitely be something worth investigating.

Essentially the inlining enabled by LTO can expose a different set of 
diagnostics.

Jeff