On Fri, May 24, 2024 at 10:46 AM Mariam Arutunian <mariamarutun...@gmail.com> wrote: > > This patch adds a new compiler pass aimed at identifying naive CRC > implementations, > characterized by the presence of a loop calculating a CRC (polynomial long > division). > Upon detection of a potential CRC, the pass prints an informational message. > > Performs CRC optimization if optimization level is >= 2, > besides optimizations for size and if fno_gimple_crc_optimization given. > > This pass is added for the detection and optimization of naive CRC > implementations, > improving the efficiency of CRC-related computations. > > This patch includes only initial fast checks for filtering out non-CRCs, > detected possible CRCs verification and optimization parts will be provided > in subsequent patches.
Just a few quick questions - I'm waiting for a revision with Jeffs comments cleared before having a closer look. The patch does nothing but analyze right now, correct? I assume a later patch will fill in stuff in ::execute and use the return value of loop_may_calculate_crc (it's a bit odd to review such a "split" thing). I think what this does fits final value replacement which lives in tree-scalar-evolution.cc and works from the loop-closed PHIs, trying to replace those. I'm not sure we want to have a separate pass for this. Consider a loop calculating two or four CRCs in parallel, replacing LC PHIs one-by-one should be able to handle this. Richard. > gcc/ > > * Makefile.in (OBJS): Add gimple-crc-optimization.o. > * common.opt (fgimple-crc-optimization): New option. > * doc/invoke.texi (-fgimple-crc-optimization): Add documentation. > * gimple-crc-optimization.cc: New file. > * gimple.cc (set_phi_stmts_not_visited): New function. > (set_gimple_stmts_not_visited): Likewise. > (set_bbs_stmts_not_visited): Likewise. > * gimple.h (set_gimple_stmts_not_visited): New extern function > declaration. > (set_phi_stmts_not_visited): New extern function declaration. > (set_bbs_stmts_not_visited): New extern function declaration. > * opts.cc (default_options_table): Add OPT_fgimple_crc_optimization. > (enable_fdo_optimizations): Enable gimple-crc-optimization. > * passes.def (pass_crc_optimization): Add new pass. > * timevar.def (TV_GIMPLE_CRC_OPTIMIZATION): New timevar. > * tree-pass.h (make_pass_crc_optimization): New extern function > declaration. > > Signed-off-by: Mariam Arutunian <mariamarutun...@gmail.com>
