Unreviewed patch

[Roger Sayle]

On Sun, 27 Jun 2004, Ulrich Weigand wrote:
> [PATCH] Re: Use-and-clobber insns and some ancient combine.c code
> http://gcc.gnu.org/ml/gcc-patches/2004-06/msg01546.html

This patch looks fine technically and conceptually, but I'd feel much
happier if it had been tested on more than just the s390 backend.
Ok for mainline provided that bootstrapping and regression testing
pass on at least one other architecture, perhaps x86 or powerpc?

My paranoia over the statement "If (reg X) is a fixed register, the
pattern shouldn't be recognized if it is not safe" requires that GCC's
backends are all correctly coded.  Ensuring that at least the most
popular GCC targets don't immediately suffer bootstrap failures, will
help support any argument that platforms that do regress, reflects
a problem with their machine descriptions, and not with this patch.

I hope this sounds reasonable.

Roger
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