This is the mail archive of the mailing list for the glibc project.

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: [PATCH v2 9/10] Tilera (and Linux asm-generic) support for glibc

On 11/11/2011 1:09 PM, Roland McGrath wrote:
2011-11-09 Chris Metcalf<>

   * bits/byteswap.h (__bswap*): Use __builtin_bswap for gcc 4.3 and
   above.  Improves code generation for gcc 4.3 and 4.4 compilers
   without bswap pattern detection.

This seems reasonable if some GCC folks can confirm that 4.3 and later produce optimal code for __builtin_bswap{32,64} on all machines.

I'm cc'ing the gcc mailing list with this reply, so if someone there can provide an authoritative statement, that would be great. It looks like right now the i386/x86_64, ia64, and s390 architecture don't use this header anyway, so it's less important for them. But powerpc and sparc do use the header (in the core glibc), and most of the architectures in the "ports" part of glibc do as well.

Roland, Joseph, if we don't hear something definitive from the gcc
folks, I'm inclined to revert this piece back to what I had in the v1
patch, where I provide a tile-specific byteswap.h using
__builtin_bswapNN(), so our gcc 4.4 will generate good code.

Chris Metcalf, Tilera Corp.

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]