On Sat, Apr 1, 2017 at 2:20 PM, Jakub Jelinek <ja...@redhat.com> wrote: > Hi! > > As discussed in the PR, in the following testcase we don't if-convert > with the generic (and many other) tuning, because we default to > --param max-rtl-if-conversion-insns=1 in most of the tunings. > The problem we have is with multiple cmov instructions, but in the > testcase there is just one cmov and the other insn is turned into a SSE > max insn, which is fine. > > This patch stops artificially lowering that param, and for one_if_conv_insn > tuning it instead rejects the if-conversion if the resulting sequence has > multiple cmov instructions. The hook is passed if_info too, so it can > in the future do better heuristics based on predictability of the edges, > how far the uses of the cmov result are (I assume cmov major problem is > latency, right?) etc. > > Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk? > > 2017-04-01 Jakub Jelinek <ja...@redhat.com> > > PR tree-optimization/79390 > * target.h (struct noce_if_info): Declare. > * targhooks.h (default_noce_conversion_profitable_p): Declare. > * target.def (noce_conversion_profitable_p): New target hook. > * ifcvt.h (struct noce_if_info): New type, moved from ... > * ifcvt.c (struct noce_if_info): ... here. > (noce_conversion_profitable_p): Renamed to ... > (default_noce_conversion_profitable_p): ... this. No longer > static nor inline. > (noce_try_store_flag_constants, noce_try_addcc, > noce_try_store_flag_mask, noce_try_cmove, noce_try_cmove_arith, > noce_convert_multiple_sets): Use targetm.noce_conversion_profitable_p > instead of noce_conversion_profitable_p. > * config/i386/i386.c: Include ifcvt.h. > (ix86_option_override_internal): Don't override > PARAM_MAX_RTL_IF_CONVERSION_INSNS default. > (ix86_noce_conversion_profitable_p): New function. > (TARGET_NOCE_CONVERSION_PROFITABLE_P): Redefine. > * config/i386/x86-tune.def (X86_TUNE_ONE_IF_CONV_INSN): Adjust > comment. > * doc/tm.texi.in (TARGET_NOCE_CONVERSION_PROFITABLE_P): Add. > * doc/tm.texi: Regenerated. > > * gcc.target/i386/pr79390.c: New test. > * gcc.dg/ifcvt-4.c: Use -mtune-ctrl=^one_if_conv_insn for i?86/x86_64.
x86 part LGTM. Hopefully, this infrastructure will allow us to fix (or it already fixes) PR 56309 [1]. [1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56309 Thanks, Uros.
