On Wed, 25 May 2011, Andrew Stubbs wrote: > So, you're saying that promoting a regular multiply to a widening multiply > isn't a valid transformation anyway? I suppose that does make sense. I knew
In general, yes. RTL always has modulo semantics (except for division and remainder by -1); all optimizations based on undefinedness of overflow (in the absence of -fwrapv) happen at tree/GIMPLE level, where signed and unsigned types are still distinct. (So you could promote a regular multiply of signed types at GIMPLE level in the absence of -fwrapv/-ftrapv, but not at RTL level and not for unsigned types at GIMPLE level.) -- Joseph S. Myers jos...@codesourcery.com
