On Tue, Nov 09, 2010 at 01:38:17PM -0500, Joern Rennecke wrote: > Quoting Paolo Bonzini <bonz...@gnu.org>: > > >On 11/09/2010 05:38 PM, Joern Rennecke wrote: > >>A define_insn will be recognized in all contexts. > >>Having an insn pattern for an insn that does not actually exist can cause > >>all kinds of unintended consequences as the optimizers try to generate > >>and recognize 'optimized' patterns, or when reload does its stuff. > > > >Before reload that is not a problem at all, I think, actually it can be > >an advantage. > > No, it is a code quality problem. And yes, I have seen actual > SH patterns being recognized that were not wanted, and lead to worse > code overall.
Generally you need to tighten the pattern conditions to make sure it doesn't match. -- Michael Meissner, IBM 5 Technology Place Drive, M/S 2757, Westford, MA 01886-3141, USA meiss...@linux.vnet.ibm.com
