[Bug rtl-optimization/47138] backport r158175: replace dominated uses in loop-invariant

["bigotp at acm dot org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47138

--- Comment #4 from Peter A. Bigot <bigotp at acm dot org> 2011-01-02 18:33:21 UTC ---
Exactly: this problem also occurs with the TI msp430 target machine
description, currently maintained as a fork on the mspgcc project on
sourceforge.  I don't know how to provide a test case other than a tar file and
patch that adds that target, and a demonstration that without the referenced
change build of libgcc fails with unrecognized instruction patterns (a parallel
clobber didn't get updated, and the assert at the bottom of
cfgrtl.c:patch_jump_insn gets hit when redirect_jump fails on a target that
isn't an exit block).

On further reflection, since this is fixed in trunk and the msp430 target
wouldn't be back-ported into your repository for an existing release series,
I'm ok with closing this as not-worth-fixing.  I did, however, want an upstream
problem report on which to hang the patches that I'll be maintaining.