On Mon, 2012-09-24 at 09:47 +0200, Oleg Endo wrote:
> On Mon, 2012-09-24 at 09:15 +0200, Eric Botcazou wrote:
> > > A while ago I've tried doing that for SH (implementing bswap16 with RTL
> > > combine). It was like an explosion of patterns, because combine would
> > > try out a lot of things depending on the surrounding code around the
> > > actual bswap16. In the end I decided to drop that stuff for the most
> > > part.
> >
> > OK, thanks for your feedback. Note that you won't get the benefit of the
> > optimization for SH if you don't define a bswaphi2 pattern.
>
> Sure sure. I'll resume my efforts after Christophe's patch is in.
>
> >
> > > BTW, the built-in documentation says:
> > >
> > > Built-in Function: int16_t __builtin_bswap16 (int16_t x)
> > > Built-in Function: int32_t __builtin_bswap32 (int32_t x)
> > >
> > > However, it seems the result is always unsigned for those.
> >
> > Yes, builtins.def contains:
> >
> > DEF_GCC_BUILTIN (BUILT_IN_BSWAP16, "bswap16", BT_FN_UINT16_UINT16,
> > ATTR_CONST_NOTHROW_LEAF_LIST)
> > DEF_GCC_BUILTIN (BUILT_IN_BSWAP32, "bswap32", BT_FN_UINT32_UINT32,
> > ATTR_CONST_NOTHROW_LEAF_LIST)
> > DEF_GCC_BUILTIN (BUILT_IN_BSWAP64, "bswap64", BT_FN_UINT64_UINT64,
> > ATTR_CONST_NOTHROW_LEAF_LIST)
> >
> > The documentation indeed needs to be fixed.
> >
>
> OK, I'll check it out.
I have committed the attached obvious patch as rev 191774.
Cheers,
Oleg
ChangeLog:
* doc/extend.texi (bswap Builtins): Change signed types to
unsigned types.
Index: gcc/doc/extend.texi
===================================================================
--- gcc/doc/extend.texi (revision 191773)
+++ gcc/doc/extend.texi (working copy)
@@ -8611,18 +8611,18 @@
are @code{long double}.
@end deftypefn
-@deftypefn {Built-in Function} int16_t __builtin_bswap16 (int16_t x)
+@deftypefn {Built-in Function} uint16_t __builtin_bswap16 (uint16_t x)
Returns @var{x} with the order of the bytes reversed; for example,
@code{0xaabb} becomes @code{0xbbaa}. Byte here always means
exactly 8 bits.
@end deftypefn
-@deftypefn {Built-in Function} int32_t __builtin_bswap32 (int32_t x)
+@deftypefn {Built-in Function} uint32_t __builtin_bswap32 (uint32_t x)
Similar to @code{__builtin_bswap16}, except the argument and return types
are 32-bit.
@end deftypefn
-@deftypefn {Built-in Function} int64_t __builtin_bswap64 (int64_t x)
+@deftypefn {Built-in Function} uint64_t __builtin_bswap64 (uint64_t x)
Similar to @code{__builtin_bswap32}, except the argument and return types
are 64-bit.
@end deftypefn
