2011/6/27 Richard Guenther <richard.guent...@gmail.com>: > On Mon, Jun 27, 2011 at 10:06 AM, Kai Tietz <kti...@redhat.com> wrote: >> Hello, >> >> this patch improves the bswap (32/64) detection and fixes an issue about >> shifted bit values out of type-size precision. >> >> ChangeLog >> >> 2011-06-27 Kai Tietz <kti...@redhat.com> >> >> * tree-ssa-math-opts.c (do_shift_rotate): Zero bits >> out of type precision after operation. >> (find_bswap): Take for limit value the integer auto- >> promotion into account. >> >> ChangeLog >> >> 2011-06-27 Kai Tietz <kti...@redhat.com> >> >> * gcc.dg/optimize-bswapdi-2.c: New test. >> >> Bootstrapped and regression tested for x86_64-pc-linux-gnu. Ok for apply? > > The do_shift_rotate hunk is ok. Where did you get the testcase from? > I can easily construct testcases that go via an intermediate SImode step > and the still won't be recongized. Thus, is the testcase practically > relevant? If so we should add 1 + log2 (byte-size) instead of 3 to also > cover the SImode -> HImode intermediate case. > > Thanks, > Richard.
Ok, I can adjust it to use here 1 + 3 (for byte-size covering the SImode -> HImode intermediate case). I was seen a regression for bswap detection by doing in forward-propagate a type-sinking on (type) X op (type) Y (for X and Y with compatible type), and (type) X op CST (for ((type) (type-x) CST) == CST case. I will sent soon a patch for this optimization related thing. By this I detected that bswap algorithm didn't zero'ed upper bits out of size-range. Ok with that change? Regards, Kai
