system.h: rename vec_step to workaround powerpc/clang bug [PR114369]

On Sat, Jul 20, 2019 at 05:26:57PM +0100, Richard Sandiford wrote:
> Gerald Pfeifer <gerald@pfeifer.com> writes:
> > I have seen an increasing number of reports of GCC failing to
> > build with clang on powerpc (on FreeBSD, though that's probably
> > immaterial).
> >
> > Turns out that clang has vec_step as a reserved word on powerpc
> > with AltiVec.
> >
> > We OTOH use vec_step s as a variable name in gcc/tree-vect-loop.c.
> >
> >
> > The best approach I can see is to rename vec_step.  Before I prepare
> > a patch: what alternate name/spelling would you prefer?
>
> Would it work to #define vec_step to vec_step_ or something on affected
> hosts, say in system.h?
>
> I'd prefer that to renmaing since "vec_step" does seem the most natural
> name for the variable.  The equivalent scalar variable is "step" and
> other vector values in the surrounding code also use the "vec_" prefix.

So like this?

If/when clang finally fixes https://github.com/llvm/llvm-project/issues/85579
on their side, we can then limit it to clang versions which still have the
bug.

I've git grepped for vec_set and appart from altivec.h it is just used in
tree-vect-loop.cc, some Ada files which aren't preprocessed, ChangeLogs,
rs6000-vecdefines.h (but that header is only included from altivec.h and
vec_step is then redefined to the function-like macro) and in rs6000-overload.def
but that file is processed with a generator, not included in C/C++ sources.

2024-03-20  Jakub Jelinek  <jakub@redhat.com>

	PR bootstrap/114369
	* system.h (vec_step): Define to vec_step_ when compiling
	with clang on PowerPC.

diff --git a/gcc/system.h b/gcc/system.h
index ab29fc19776446cb48052f4f5990317d4bf681e5..1028dcb1eb3c741d517d6f4ef3a65d7c48a8f49b 100644 (file)
--- a/gcc/system.h
+++ b/gcc/system.h
@@ -1302,6 +1302,12 @@ void gcc_stablesort_r (void *, size_t, size_t, sort_r_cmp_fn *, void *data);
 #define NULL nullptr
 #endif
 
+/* Workaround clang on PowerPC which has vec_step as reserved keyword
+   rather than function-like macro defined in <altivec.h>.  See PR114369.  */
+#if defined(__clang__) && defined(__powerpc__)
+#define vec_step vec_step_
+#endif
+
 /* Return true if STR string starts with PREFIX.  */
 
 inline bool