On Wed, May 13, 2015 at 03:55:10PM +0200, Jakub Jelinek wrote: > On Wed, May 13, 2015 at 03:41:11PM +0200, Marek Polacek wrote: > > As discussed in the PR, match.pd happily folds 0 * whatever into 0. That > > is undesirable from the C/C++ FE POV, since it can make us accept invalid > > initializers. > > > > So fixed in match.pd -- I'd hope there's a better way to do this, but this > > seems to work. There was some fallout, but nothing unexpected or > > surprising. > > Will it handle cases 0 * (int) (1 / 0) etc., when perhaps the division by > zero isn't immediately the operand of mult, but somewhere deeper?
It won't handle e.g. 0 * (unsigned) (1 / 0). > Also, can't the divisor be optimized into 0 only later on, so your code > would still see !integer_zerop there and fold into 0? > Perhaps the answer is that in both cases we'd have simplified those already > into a division by zero. Yes, it's a dumb attempt. I don't know how to reliably fix this :(. We really want <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66127#c1>... Marek
