Hello, I "confiigure"d with --with-long-double-128 but that doesn't seem to have any effect at all. I still get sizeof(long double) as 12 bytes. [gcc]:45 $ gcc -v Using built-in specs. COLLECT_GCC=gcc COLLECT_LTO_WRAPPER=/home/bdsatish/gnu/installed/gcc/libexec/gcc/i786-pc-linux-gnu/4.7.0/lto-wrapper Target: i786-pc-linux-gnu Configured with: ./configure --prefix=/home/bdsatish/gnu/installed/gcc --enable-languages=c --build=i786-pc-linux-gnu --enable-checking=release --disable-libmudflap --enable-libgomp --disable-shared --disable-bootstrap --with-long-double-128 --with-system-zlib Thread model: posix gcc version 4.7.0 20110326 (experimental) (GCC) -- Satish.BD On Sun, Mar 27, 2011 at 5:33 PM, Dr. David Kirkby <david.kirkby@xxxxxxxxxx> wrote: > On 03/27/11 01:29 PM, bd satish wrote: >> >> Hi, >> >> I am trying to build gcc and ÂI would like gcc to map (by default) >> "long double" Âto 128-bit. >> What option should I pass to "configure" script to get this behaviour ? >> >> I'm running a 32-bit OS [ Ubuntu 10.10 ] on intel core i3 processor. >> Currently sizeof( long double) prints 12 bytes, i.e., 96 bits. >> >> PS: I do not like to specify the flag "-m128bit-long-double" to every >> C program I compile. Instead, I want gcc to use 16-byte (128-bit) by >> default without the end user having to specify this flag. ÂIs this >> possible ? >> >> For sake of completeness, >> >> [gnu]:15 $ gcc -v >> Using built-in specs. >> COLLECT_GCC=gcc >> >> COLLECT_LTO_WRAPPER=/home/god/gcc/libexec/gcc/i786-pc-linux-gnu/4.7.0/lto-wrapper >> Target: i786-pc-linux-gnu >> Configured with: ./configure --prefix=/home/god/gnu/installed/gcc >> --enable-languages=c,fortran --build=i786-pc-linux-gnu >> --enable-checking=release --disable-libmudflap --enable-libgomp >> --disable-shared --disable-bootstrap >> Thread model: posix >> gcc version 4.7.0 20110319 (experimental) (GCC) >> >> >> Thanks ! > > I don't know if this works on any platform (read the docs), but on the gcc I > downloaded for the AIX operating system, there was an option to the > 'configure' script which might do what you want. Here's how gcc was built on > AIX > > -bash-4.1$ gcc -v > Using built-in specs. > Target: powerpc-ibm-aix5.3.0.0 > Configured with: ../stage/gcc-4.2.4/configure --disable-shared > --enable-threads=posix --prefix=/opt/pware --with-long-double-128 > --with-mpfr=/opt/pware --with-gmp=/opt/pware > Thread model: aix > gcc version 4.2.4 > -bash-4.1$ > > I assume 128 bit long doubles will be much slower, as this would have to be > implemented in sofware, whereas I think the 12-byte long double can be done > in hardware on the x86 chips, as the floating point processor uses 80 bits > internally. > > -- > A: Because it messes up the order in which people normally read text. > Q: Why is top-posting such a bad thing? > A: Top-posting. > Q: What is the most annoying thing in e-mail? > > Dave > >
