On Fri, Aug 19, 2016 at 4:45 PM, H.J. Lu <hjl.to...@gmail.com> wrote: > On Fri, Aug 19, 2016 at 2:21 AM, Richard Biener > <richard.guent...@gmail.com> wrote: >> On Thu, Aug 18, 2016 at 5:16 PM, H.J. Lu <hjl.to...@gmail.com> wrote: >>> On Thu, Aug 18, 2016 at 1:18 AM, Richard Biener >>> <richard.guent...@gmail.com> wrote: >>>> On Wed, Aug 17, 2016 at 10:11 PM, H.J. Lu <hongjiu...@intel.com> wrote: >>>>> builtin_memset_gen_str returns a register used for memset, which only >>>>> supports integer registers. But a target may use vector registers in >>>>> memmset. This patch adds a TARGET_GEN_MEMSET_VALUE hook to duplicate >>>>> QImode value to mode derived from STORE_MAX_PIECES, which can be used >>>>> with vector instructions. The default hook is the same as the original >>>>> builtin_memset_gen_str. A target can override it to support vector >>>>> instructions for STORE_MAX_PIECES. >>>>> >>>>> Tested on x86-64 and i686. Any comments? >>>>> >>>>> H.J. >>>>> --- >>>>> gcc/ >>>>> >>>>> * builtins.c (builtin_memset_gen_str): Call >>>>> targetm.gen_memset_value. >>>>> (default_gen_memset_value): New function. >>>>> * target.def (gen_memset_value): New hook. >>>>> * targhooks.c: Inclue "expmed.h" and "builtins.h". >>>>> (default_gen_memset_value): New function. >>>> >>>> I see default_gen_memset_value in builtins.c but it belongs here. >>>> >>>>> * targhooks.h (default_gen_memset_value): New prototype. >>>>> * config/i386/i386.c (ix86_gen_memset_value): New function. >>>>> (TARGET_GEN_MEMSET_VALUE): New. >>>>> * config/i386/i386.h (STORE_MAX_PIECES): Likewise. >>>>> * doc/tm.texi.in: Add TARGET_GEN_MEMSET_VALUE hook. >>>>> * doc/tm.texi: Updated. >>>>> >>> >>> Like this? >> >> Aww, ok - I see builtins.c is a better place - sorry for the extra work. >> >> Richard. > > Here is the original patch with the updated ChangeLog. OK for trunk?
So now actually looking at what you are doing. Why do we need a new hook? Is it that even if we make builtin_memset_gen_str handle vector-mode MODE properly you don't get the desired optimized code? Your patch doesn't seem to change the mode to vector but only STORE_MAX_PIECES and op_by_pieces_d::run will only consider integer modes. So isn't this a general missed optimization that TImode 0x01010101...01 * x is not optimized to a pxor or broadcast? Thanks, Richard. > > -- > H.J.
