> So the fix is a one-liner that sets subst_low_luid before the > expand_field_assignment() call. Bootstrapped and tested under i686, > x86-64, powerpc64. Cross-tested on ARM. I was a bit weary that some > optimization regression might appear, which will complicate things, but > everything looks fine. > > I have a larger (customer provided) testcase that exposed this bug after > rev.161655 (the mem-ref2 merge, may be related to effects on bitfields). > So if suitable, please also approve this patch for 4.6/4.7 branches. > > Thanks, > Chung-Lin > > 2012-03-10 Chung-Lin Tang <clt...@codesourcery.com> > > PR rtl-optimization/52528 > * combine.c (can_combine_p): Add setting of subst_low_luid > before call to expand_field_assignment().
OK for mainline, 4.7 branch (once 4.7.0 is released) and 4.6 branch, modulo: + /* The simplification in expand_field_assignment() may call back to + get_last_value(), so set safe guard here. */ + subst_low_luid = DF_INSN_LUID (insn); No () in comments, just use the function name. -- Eric Botcazou