On 10/14/14 10:02, Jakub Jelinek wrote:
Hi!When hacking on range reassoc opt, I've noticed we can emit code with undefined behavior even when there wasn't one originally, in particular for: (X - 43U) <= 3U || (X - 75U) <= 3U and this loop can transform that into ((X - 43U) & ~(75U - 43U)) <= 3U. */ we actually don't transform it to what the comment says, but ((X - 43) & ~(75U - 43U)) <= 3U i.e. the initial subtraction can be performed in signed type, if in here X is e.g. INT_MIN or INT_MIN + 42, the subtraction at gimple level would be UB (not caught by -fsanitize=undefined, because that is handled much earlier). Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk? 2014-10-14 Jakub Jelinek <ja...@redhat.com> * tree-ssa-reassoc.c (optimize_range_tests_diff): Perform MINUS_EXPR in unsigned type to avoid undefined behavior.
Any chance this fixes: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63302 Jeff
