Patchwork New parameters to control stringop expansion libcall strategy

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Submitter Xinliang David Li
Date Aug. 7, 2013, 5:06 p.m.
Message ID <CAAkRFZL96-tNbQxtB16cUaPN7OHAFNa7rTF1pfpKP-+GMWK1_w@mail.gmail.com>
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Permalink /patch/265571/
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Xinliang David Li - Aug. 7, 2013, 5:06 p.m.
Fixed the do while formatting.  Ok for trunk with this version?

thanks,

David

On Tue, Aug 6, 2013 at 2:42 AM, Jan Hubicka <hubicka@ucw.cz> wrote:
>> >>> 2013-08-02  Xinliang David Li  <davidxl@google.com>
>> >>>
>> >>>         * config/i386/stringop.def: New file.
>> >>>         * config/i386/stringop.opt: New file.
>> >>>         * config/i386/i386-opts.h: Include stringopt.def.
>> >>>         * config/i386/i386.opt: Include stringopt.opt.
>> >>>         * config/i386/i386.c (ix86_option_override_internal):
>> >>>         Override default size based stringop inline strategies
>> >>>         with options.
>> >>>         * config/i386/i386.c (ix86_parse_stringop_strategy_string):
>> >>>         New function.
>> >>>
>> >>> 2013-08-04  Xinliang David Li  <davidxl@google.com>
>> >>>
>> >>>         * testsuite/gcc.target/i386/memcpy-strategy-1.c: New test.
>> >>>         * testsuite/gcc.target/i386/memcpy-strategy-2.c: Ditto.
>> >>>         * testsuite/gcc.target/i386/memset-strategy-1.c: Ditto.
>> >>>         * testsuite/gcc.target/i386/memcpy-strategy-3.c: Ditto.
>
> The patch looks resonable to me in general.  I wonder why we need to bring
> all the cost tables non-const instead of just having writable storage for
> the "current strategy" like we do with other flags anyway.
>
> Your strings are definitely more readable than the in-memory representation
> I came up with. Perhaps we can even turn the cost tables into strings
> for easier maintenance?  I guess they are bit confusing for people
> not familiar with a code.
>
> Honza
>> >>>
>> >>>
>> >>>
>> >>>
>> >>> On Fri, Aug 2, 2013 at 9:21 PM, Xinliang David Li <davidxl@google.com> wrote:
>> >>> > On x86_64, when the expected size of memcpy/memset is known (e.g, with
>> >>> > FDO), libcall strategy is used with the size is > 8192. This value is
>> >>> > hard coded, which makes it hard to do performance tuning. This patch
>> >>> > adds two new parameters to do that. Potential usage includes
>> >>> > per-application libcall strategy min-size tuning based on summary data
>> >>> > with FDO (e.g, instruction workset size).
>> >>> >
>> >>> > Bootstrap and tested on x86_64/linux. Ok for trunk?
>> >>> >
>> >>> > thanks,
>> >>> >
>> >>> > David
>> >>> >
>> >>> >
>> >>> > 2013-08-02  Xinliang David Li  <davidxl@google.com>
>> >>> >
>> >>> >         * params.def: New parameters.
>> >>> >         * config/i386/i386.c (ix86_option_override_internal):
>> >>> >         Override default libcall size limit with parameters.
>> >>
>> >>> Index: config/i386/stringop.def
>> >>> ===================================================================
>> >>> --- config/i386/stringop.def  (revision 0)
>> >>> +++ config/i386/stringop.def  (revision 0)
>> >>> @@ -0,0 +1,42 @@
>> >>> +/* Definitions for option handling for IA-32.
>> >>> +   Copyright (C) 2013 Free Software Foundation, Inc.
>> >>> +
>> >>> +This file is part of GCC.
>> >>> +
>> >>> +GCC is free software; you can redistribute it and/or modify
>> >>> +it under the terms of the GNU General Public License as published by
>> >>> +the Free Software Foundation; either version 3, or (at your option)
>> >>> +any later version.
>> >>> +
>> >>> +GCC is distributed in the hope that it will be useful,
>> >>> +but WITHOUT ANY WARRANTY; without even the implied warranty of
>> >>> +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> >>> +GNU General Public License for more details.
>> >>> +
>> >>> +Under Section 7 of GPL version 3, you are granted additional
>> >>> +permissions described in the GCC Runtime Library Exception, version
>> >>> +3.1, as published by the Free Software Foundation.
>> >>> +
>> >>> +You should have received a copy of the GNU General Public License and
>> >>> +a copy of the GCC Runtime Library Exception along with this program;
>> >>> +see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
>> >>> +<http://www.gnu.org/licenses/>.  */
>> >>> +
>> >>> +DEF_ENUM
>> >>> +DEF_ALG (no_stringop, no_stringop)
>> >>> +DEF_ENUM
>> >>> +DEF_ALG (libcall, libcall)
>> >>> +DEF_ENUM
>> >>> +DEF_ALG (rep_prefix_1_byte, rep_byte)
>> >>> +DEF_ENUM
>> >>> +DEF_ALG (rep_prefix_4_byte, rep_4byte)
>> >>> +DEF_ENUM
>> >>> +DEF_ALG (rep_prefix_8_byte, rep_8byte)
>> >>> +DEF_ENUM
>> >>> +DEF_ALG (loop_1_byte, byte_loop)
>> >>> +DEF_ENUM
>> >>> +DEF_ALG (loop, loop)
>> >>> +DEF_ENUM
>> >>> +DEF_ALG (unrolled_loop, unrolled_loop)
>> >>> +DEF_ENUM
>> >>> +DEF_ALG (vector_loop, vector_loop)
>> >>> Index: config/i386/i386.opt
>> >>> ===================================================================
>> >>> --- config/i386/i386.opt      (revision 201458)
>> >>> +++ config/i386/i386.opt      (working copy)
>> >>> @@ -316,6 +316,14 @@ mstack-arg-probe
>> >>>  Target Report Mask(STACK_PROBE) Save
>> >>>  Enable stack probing
>> >>>
>> >>> +mmemcpy-strategy=
>> >>> +Target RejectNegative Joined Var(ix86_tune_memcpy_strategy)
>> >>> +Specify memcpy expansion strategy when expected size is known
>> >>> +
>> >>> +mmemset-strategy=
>> >>> +Target RejectNegative Joined Var(ix86_tune_memset_strategy)
>> >>> +Specify memset expansion strategy when expected size is known
>> >>> +
>> >>>  mstringop-strategy=
>> >>>  Target RejectNegative Joined Enum(stringop_alg) Var(ix86_stringop_alg) Init(no_stringop)
>> >>>  Chose strategy to generate stringop using
>> >>> Index: config/i386/stringop.opt
>> >>> ===================================================================
>> >>> --- config/i386/stringop.opt  (revision 0)
>> >>> +++ config/i386/stringop.opt  (revision 0)
>> >>> @@ -0,0 +1,36 @@
>> >>> +/* Definitions for option handling for IA-32.
>> >>> +   Copyright (C) 2013 Free Software Foundation, Inc.
>> >>> +
>> >>> +This file is part of GCC.
>> >>> +
>> >>> +GCC is free software; you can redistribute it and/or modify
>> >>> +it under the terms of the GNU General Public License as published by
>> >>> +the Free Software Foundation; either version 3, or (at your option)
>> >>> +any later version.
>> >>> +
>> >>> +GCC is distributed in the hope that it will be useful,
>> >>> +but WITHOUT ANY WARRANTY; without even the implied warranty of
>> >>> +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> >>> +GNU General Public License for more details.
>> >>> +
>> >>> +Under Section 7 of GPL version 3, you are granted additional
>> >>> +permissions described in the GCC Runtime Library Exception, version
>> >>> +3.1, as published by the Free Software Foundation.
>> >>> +
>> >>> +You should have received a copy of the GNU General Public License and
>> >>> +a copy of the GCC Runtime Library Exception along with this program;
>> >>> +see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
>> >>> +<http://www.gnu.org/licenses/>.  */
>> >>> +
>> >>> +Enum(stringop_alg) String(rep_byte) Value(rep_prefix_1_byte)
>> >>> +
>> >>> +#undef DEF_ENUM
>> >>> +#define DEF_ENUM EnumValue
>> >>> +
>> >>> +#undef DEF_ALG
>> >>> +#define DEF_ALG(alg, name) Enum(stringop_alg) String(name) Value(alg)
>> >>> +
>> >>> +#include "stringop.def"
>> >>> +
>> >>> +#undef DEF_ENUM
>> >>> +#undef DEF_ALG
>> >>> Index: config/i386/i386.c
>> >>> ===================================================================
>> >>> --- config/i386/i386.c        (revision 201458)
>> >>> +++ config/i386/i386.c        (working copy)
>> >>> @@ -156,7 +156,7 @@ struct processor_costs ix86_size_cost =
>> >>>  };
>> >>>
>> >>>  /* Processor costs (relative to an add) */
>> >>> -static const
>> >>> +static
>> >>>  struct processor_costs i386_cost = { /* 386 specific costs */
>> >>>    COSTS_N_INSNS (1),                 /* cost of an add instruction */
>> >>>    COSTS_N_INSNS (1),                 /* cost of a lea instruction */
>> >>> @@ -226,7 +226,7 @@ struct processor_costs i386_cost = {      /*
>> >>>    1,                                 /* cond_not_taken_branch_cost.  */
>> >>>  };
>> >>>
>> >>> -static const
>> >>> +static
>> >>>  struct processor_costs i486_cost = { /* 486 specific costs */
>> >>>    COSTS_N_INSNS (1),                 /* cost of an add instruction */
>> >>>    COSTS_N_INSNS (1),                 /* cost of a lea instruction */
>> >>> @@ -298,7 +298,7 @@ struct processor_costs i486_cost = {      /*
>> >>>    1,                                 /* cond_not_taken_branch_cost.  */
>> >>>  };
>> >>>
>> >>> -static const
>> >>> +static
>> >>>  struct processor_costs pentium_cost = {
>> >>>    COSTS_N_INSNS (1),                 /* cost of an add instruction */
>> >>>    COSTS_N_INSNS (1),                 /* cost of a lea instruction */
>> >>> @@ -368,7 +368,7 @@ struct processor_costs pentium_cost = {
>> >>>    1,                                 /* cond_not_taken_branch_cost.  */
>> >>>  };
>> >>>
>> >>> -static const
>> >>> +static
>> >>>  struct processor_costs pentiumpro_cost = {
>> >>>    COSTS_N_INSNS (1),                 /* cost of an add instruction */
>> >>>    COSTS_N_INSNS (1),                 /* cost of a lea instruction */
>> >>> @@ -447,7 +447,7 @@ struct processor_costs pentiumpro_cost =
>> >>>    1,                                 /* cond_not_taken_branch_cost.  */
>> >>>  };
>> >>>
>> >>> -static const
>> >>> +static
>> >>>  struct processor_costs geode_cost = {
>> >>>    COSTS_N_INSNS (1),                 /* cost of an add instruction */
>> >>>    COSTS_N_INSNS (1),                 /* cost of a lea instruction */
>> >>> @@ -518,7 +518,7 @@ struct processor_costs geode_cost = {
>> >>>    1,                                 /* cond_not_taken_branch_cost.  */
>> >>>  };
>> >>>
>> >>> -static const
>> >>> +static
>> >>>  struct processor_costs k6_cost = {
>> >>>    COSTS_N_INSNS (1),                 /* cost of an add instruction */
>> >>>    COSTS_N_INSNS (2),                 /* cost of a lea instruction */
>> >>> @@ -591,7 +591,7 @@ struct processor_costs k6_cost = {
>> >>>    1,                                 /* cond_not_taken_branch_cost.  */
>> >>>  };
>> >>>
>> >>> -static const
>> >>> +static
>> >>>  struct processor_costs athlon_cost = {
>> >>>    COSTS_N_INSNS (1),                 /* cost of an add instruction */
>> >>>    COSTS_N_INSNS (2),                 /* cost of a lea instruction */
>> >>> @@ -664,7 +664,7 @@ struct processor_costs athlon_cost = {
>> >>>    1,                                 /* cond_not_taken_branch_cost.  */
>> >>>  };
>> >>>
>> >>> -static const
>> >>> +static
>> >>>  struct processor_costs k8_cost = {
>> >>>    COSTS_N_INSNS (1),                 /* cost of an add instruction */
>> >>>    COSTS_N_INSNS (2),                 /* cost of a lea instruction */
>> >>> @@ -1265,7 +1265,7 @@ struct processor_costs btver2_cost = {
>> >>>    1,                                 /* cond_not_taken_branch_cost.  */
>> >>>  };
>> >>>
>> >>> -static const
>> >>> +static
>> >>>  struct processor_costs pentium4_cost = {
>> >>>    COSTS_N_INSNS (1),                 /* cost of an add instruction */
>> >>>    COSTS_N_INSNS (3),                 /* cost of a lea instruction */
>> >>> @@ -1336,7 +1336,7 @@ struct processor_costs pentium4_cost = {
>> >>>    1,                                 /* cond_not_taken_branch_cost.  */
>> >>>  };
>> >>>
>> >>> -static const
>> >>> +static
>> >>>  struct processor_costs nocona_cost = {
>> >>>    COSTS_N_INSNS (1),                 /* cost of an add instruction */
>> >>>    COSTS_N_INSNS (1),                 /* cost of a lea instruction */
>> >>> @@ -1409,7 +1409,7 @@ struct processor_costs nocona_cost = {
>> >>>    1,                                 /* cond_not_taken_branch_cost.  */
>> >>>  };
>> >>>
>> >>> -static const
>> >>> +static
>> >>>  struct processor_costs atom_cost = {
>> >>>    COSTS_N_INSNS (1),                 /* cost of an add instruction */
>> >>>    COSTS_N_INSNS (1) + 1,             /* cost of a lea instruction */
>> >>> @@ -1556,7 +1556,7 @@ struct processor_costs slm_cost = {
>> >>>  };
>> >>>
>> >>>  /* Generic64 should produce code tuned for Nocona and K8.  */
>> >>> -static const
>> >>> +static
>> >>>  struct processor_costs generic64_cost = {
>> >>>    COSTS_N_INSNS (1),                 /* cost of an add instruction */
>> >>>    /* On all chips taken into consideration lea is 2 cycles and more.  With
>> >>> @@ -1635,7 +1635,7 @@ struct processor_costs generic64_cost =
>> >>>  };
>> >>>
>> >>>  /* core_cost should produce code tuned for Core familly of CPUs.  */
>> >>> -static const
>> >>> +static
>> >>>  struct processor_costs core_cost = {
>> >>>    COSTS_N_INSNS (1),                 /* cost of an add instruction */
>> >>>    /* On all chips taken into consideration lea is 2 cycles and more.  With
>> >>> @@ -1717,7 +1717,7 @@ struct processor_costs core_cost = {
>> >>>
>> >>>  /* Generic32 should produce code tuned for PPro, Pentium4, Nocona,
>> >>>     Athlon and K8.  */
>> >>> -static const
>> >>> +static
>> >>>  struct processor_costs generic32_cost = {
>> >>>    COSTS_N_INSNS (1),                 /* cost of an add instruction */
>> >>>    COSTS_N_INSNS (1) + 1,             /* cost of a lea instruction */
>> >>> @@ -2900,6 +2900,150 @@ ix86_debug_options (void)
>> >>>
>> >>>    return;
>> >>>  }
>> >>> +
>> >>> +static const char *stringop_alg_names[] = {
>> >>> +#define DEF_ENUM
>> >>> +#define DEF_ALG(alg, name) #name,
>> >>> +#include "stringop.def"
>> >>> +#undef DEF_ENUM
>> >>> +#undef DEF_ALG
>> >>> +};
>> >>> +
>> >>> +/* Parse parameter string passed to -mmemcpy-strategy= or -mmemset-strategy=.
>> >>> +   The string is of the following form (or comma separated list of it):
>> >>> +
>> >>> +     strategy_alg:max_size:[align|noalign]
>> >>> +
>> >>> +   where the full size range for the strategy is either [0, max_size] or
>> >>> +   [min_size, max_size], in which min_size is the max_size + 1 of the
>> >>> +   preceding range.  The last size range must have max_size == -1.
>> >>> +
>> >>> +   Examples:
>> >>> +
>> >>> +    1.
>> >>> +       -mmemcpy-strategy=libcall:-1:noalign
>> >>> +
>> >>> +      this is equivalent to (for known size memcpy) -mstringop-strategy=libcall
>> >>> +
>> >>> +
>> >>> +   2.
>> >>> +      -mmemset-strategy=rep_8byte:16:noalign,vector_loop:2048:align,libcall:-1:noalign
>> >>> +
>> >>> +      This is to tell the compiler to use the following strategy for memset
>> >>> +      1) when the expected size is between [1, 16], use rep_8byte strategy;
>> >>> +      2) when the size is between [17, 2048], use vector_loop;
>> >>> +      3) when the size is > 2048, use libcall.
>> >>> +
>> >>> +*/
>> >>> +
>> >>> +struct stringop_size_range
>> >>> +{
>> >>> +  int min;
>> >>> +  int max;
>> >>> +  stringop_alg alg;
>> >>> +  bool noalign;
>> >>> +};
>> >>> +
>> >>> +static void
>> >>> +ix86_parse_stringop_strategy_string (char *strategy_str, bool is_memset)
>> >>> +{
>> >>> +  const struct stringop_algs *default_algs;
>> >>> +  stringop_size_range input_ranges[MAX_STRINGOP_ALGS];
>> >>> +  char *curr_range_str, *next_range_str;
>> >>> +  int i = 0, n = 0;
>> >>> +
>> >>> +  if (is_memset)
>> >>> +    default_algs = &ix86_cost->memset[TARGET_64BIT != 0];
>> >>> +  else
>> >>> +    default_algs = &ix86_cost->memcpy[TARGET_64BIT != 0];
>> >>> +
>> >>> +  curr_range_str = strategy_str;
>> >>> +
>> >>> +  do {
>> >>> +
>> >>> +    int mins, maxs;
>> >>> +    stringop_alg alg;
>> >>> +    char alg_name[128];
>> >>> +    char align[16];
>> >>> +
>> >>> +    next_range_str = strchr (curr_range_str, ',');
>> >>> +    if (next_range_str)
>> >>> +      *next_range_str++ = '\0';
>> >>> +
>> >>> +    if (3 != sscanf (curr_range_str, "%[^:]:%d:%s", alg_name, &maxs, align))
>> >>> +      {
>> >>> +        warning (0, "Wrong arg %s to option %s", curr_range_str,
>> >>> +                 is_memset ? "-mmemset_strategy=" : "-mmemcpy_strategy=");
>> >>> +        return;
>> >>> +      }
>> >>> +
>> >>> +    if (n > 0 && (maxs < (mins = input_ranges[n - 1].max + 1) && maxs != -1))
>> >>> +      {
>> >>> +        warning (0, "Size ranges of option %s should be increasing",
>> >>> +                 is_memset ? "-mmemset_strategy=" : "-mmemcpy_strategy=");
>> >>> +        return;
>> >>> +      }
>> >>> +
>> >>> +    for (i = 0; i < last_alg; i++)
>> >>> +      {
>> >>> +        if (!strcmp (alg_name, stringop_alg_names[i]))
>> >>> +       {
>> >>> +         alg = (stringop_alg) i;
>> >>> +         break;
>> >>> +          }
>> >>> +      }
>> >>> +
>> >>> +    if (i == last_alg)
>> >>> +      {
>> >>> +        warning (0, "Wrong stringop strategy name %s specified for option %s",
>> >>> +              alg_name,
>> >>> +                 is_memset ? "-mmemset_strategy=" : "-mmemcpy_strategy=");
>> >>> +     return;
>> >>> +      }
>> >>> +
>> >>> +    input_ranges[n].min = mins;
>> >>> +    input_ranges[n].max = maxs;
>> >>> +    input_ranges[n].alg = alg;
>> >>> +    if (!strcmp (align, "align"))
>> >>> +      input_ranges[n].noalign = false;
>> >>> +    else if (!strcmp (align, "noalign"))
>> >>> +      input_ranges[n].noalign = true;
>> >>> +    else
>> >>> +      {
>> >>> +        warning (0, "Unknown alignment %s specified for option %s",
>> >>> +                 align, is_memset ? "-mmemset_strategy=" : "-mmemcpy_strategy=");
>> >>> +        return;
>> >>> +      }
>> >>> +    n++;
>> >>> +    curr_range_str = next_range_str;
>> >>> +  } while (curr_range_str);
>> >>> +
>> >>> +  if (input_ranges[n - 1].max != -1)
>> >>> +    {
>> >>> +      warning (0, "The max value for the last size range should be -1"
>> >>> +               " for option %s",
>> >>> +               is_memset ? "-mmemset_strategy=" : "-mmemcpy_strategy=");
>> >>> +      return;
>> >>> +    }
>> >>> +
>> >>> +  if (n > MAX_STRINGOP_ALGS)
>> >>> +    {
>> >>> +      warning (0, "Too many size ranges specified in option %s",
>> >>> +               is_memset ? "-mmemset_strategy=" : "-mmemcpy_strategy=");
>> >>> +      return;
>> >>> +    }
>> >>> +
>> >>> +  /* Now override the default algs array  */
>> >>> +  for (i = 0; i < n; i++)
>> >>> +    {
>> >>> +      *const_cast<int *>(&default_algs->size[i].max) = input_ranges[i].max;
>> >>> +      *const_cast<stringop_alg *>(&default_algs->size[i].alg)
>> >>> +          = input_ranges[i].alg;
>> >>> +      *const_cast<int *>(&default_algs->size[i].noalign)
>> >>> +          = input_ranges[i].noalign;
>> >>> +    }
>> >>> +}
>> >>> +
>> >>>
>> >>>  /* Override various settings based on options.  If MAIN_ARGS_P, the
>> >>>     options are from the command line, otherwise they are from
>> >>> @@ -4021,6 +4165,21 @@ ix86_option_override_internal (bool main
>> >>>    /* Handle stack protector */
>> >>>    if (!global_options_set.x_ix86_stack_protector_guard)
>> >>>      ix86_stack_protector_guard = TARGET_HAS_BIONIC ? SSP_GLOBAL : SSP_TLS;
>> >>> +
>> >>> +  /* Handle -mmemcpy-strategy= and -mmemset-strategy=  */
>> >>> +  if (ix86_tune_memcpy_strategy)
>> >>> +    {
>> >>> +      char *str = xstrdup (ix86_tune_memcpy_strategy);
>> >>> +      ix86_parse_stringop_strategy_string (str, false);
>> >>> +      free (str);
>> >>> +    }
>> >>> +
>> >>> +  if (ix86_tune_memset_strategy)
>> >>> +    {
>> >>> +      char *str = xstrdup (ix86_tune_memset_strategy);
>> >>> +      ix86_parse_stringop_strategy_string (str, true);
>> >>> +      free (str);
>> >>> +    }
>> >>>  }
>> >>>
>> >>>  /* Implement the TARGET_OPTION_OVERRIDE hook.  */
>> >>> @@ -22903,6 +23062,7 @@ ix86_expand_movmem (rtx dst, rtx src, rt
>> >>>      {
>> >>>      case libcall:
>> >>>      case no_stringop:
>> >>> +    case last_alg:
>> >>>        gcc_unreachable ();
>> >>>      case loop_1_byte:
>> >>>        need_zero_guard = true;
>> >>> @@ -23093,6 +23253,7 @@ ix86_expand_movmem (rtx dst, rtx src, rt
>> >>>      {
>> >>>      case libcall:
>> >>>      case no_stringop:
>> >>> +    case last_alg:
>> >>>        gcc_unreachable ();
>> >>>      case loop_1_byte:
>> >>>      case loop:
>> >>> @@ -23304,6 +23465,7 @@ ix86_expand_setmem (rtx dst, rtx count_e
>> >>>      {
>> >>>      case libcall:
>> >>>      case no_stringop:
>> >>> +    case last_alg:
>> >>>        gcc_unreachable ();
>> >>>      case loop:
>> >>>        need_zero_guard = true;
>> >>> @@ -23481,6 +23643,7 @@ ix86_expand_setmem (rtx dst, rtx count_e
>> >>>      {
>> >>>      case libcall:
>> >>>      case no_stringop:
>> >>> +    case last_alg:
>> >>>        gcc_unreachable ();
>> >>>      case loop_1_byte:
>> >>>      case loop:
>> >>> Index: config/i386/i386-opts.h
>> >>> ===================================================================
>> >>> --- config/i386/i386-opts.h   (revision 201458)
>> >>> +++ config/i386/i386-opts.h   (working copy)
>> >>> @@ -28,15 +28,17 @@ see the files COPYING3 and COPYING.RUNTI
>> >>>  /* Algorithm to expand string function with.  */
>> >>>  enum stringop_alg
>> >>>  {
>> >>> -   no_stringop,
>> >>> -   libcall,
>> >>> -   rep_prefix_1_byte,
>> >>> -   rep_prefix_4_byte,
>> >>> -   rep_prefix_8_byte,
>> >>> -   loop_1_byte,
>> >>> -   loop,
>> >>> -   unrolled_loop,
>> >>> -   vector_loop
>> >>> +#undef DEF_ENUM
>> >>> +#define DEF_ENUM
>> >>> +
>> >>> +#undef DEF_ALG
>> >>> +#define DEF_ALG(alg, name) alg,
>> >>> +
>> >>> +#include "stringop.def"
>> >>> +last_alg
>> >>> +
>> >>> +#undef DEF_ENUM
>> >>> +#undef DEF_ALG
>> >>>  };
>> >>>
>> >>>  /* Available call abi.  */
>> >>> Index: doc/invoke.texi
>> >>> ===================================================================
>> >>> --- doc/invoke.texi   (revision 201458)
>> >>> +++ doc/invoke.texi   (working copy)
>> >>> @@ -649,6 +649,7 @@ Objective-C and Objective-C++ Dialects}.
>> >>>  -mbmi2 -mrtm -mlwp -mthreads @gol
>> >>>  -mno-align-stringops  -minline-all-stringops @gol
>> >>>  -minline-stringops-dynamically -mstringop-strategy=@var{alg} @gol
>> >>> +-mmemcpy-strategy=@var{strategy} -mmemset-strategy=@var{strategy}
>> >>>  -mpush-args  -maccumulate-outgoing-args  -m128bit-long-double @gol
>> >>>  -m96bit-long-double -mlong-double-64 -mlong-double-80 @gol
>> >>>  -mregparm=@var{num}  -msseregparm @gol
>> >>> @@ -14598,6 +14599,24 @@ Expand into an inline loop.
>> >>>  Always use a library call.
>> >>>  @end table
>> >>>
>> >>> +@item -mmemcpy-strategy=@var{strategy}
>> >>> +@opindex mmemcpy-strategy=@var{strategy}
>> >>> +Override the internal decision heuristic to decide if @code{__builtin_memcpy}
>> >>> +should be inlined and what inline algorithm to use when the expected size
>> >>> +of the copy operation is known. @var{strategy}
>> >>> +is a comma-separated list of @var{alg}:@var{max_size}:@var{dest_align} triplets.
>> >>> +@var{alg} is specified in @option{-mstringop-strategy}, @var{max_size} specifies
>> >>> +the max byte size with which inline algorithm @var{alg} is allowed. For the last
>> >>> +triplet, the @var{max_size} must be @code{-1}. The @var{max_size} of the triplets
>> >>> +in the list must be specified in increasing order. The minimal byte size for
>> >>> +@var{alg} is @code{0} for the first triplet and @code{@var{max_size} + 1} of the
>> >>> +preceding range.
>> >>> +
>> >>> +@item -mmemset-strategy=@var{strategy}
>> >>> +@opindex mmemset-strategy=@var{strategy}
>> >>> +The option is similar to @option{-mmemcpy-strategy=} except that it is to control
>> >>> +@code{__builtin_memset} expansion.
>> >>> +
>> >>>  @item -momit-leaf-frame-pointer
>> >>>  @opindex momit-leaf-frame-pointer
>> >>>  Don't keep the frame pointer in a register for leaf functions.  This
>> >>> Index: testsuite/gcc.target/i386/memcpy-strategy-1.c
>> >>> ===================================================================
>> >>> --- testsuite/gcc.target/i386/memcpy-strategy-1.c     (revision 0)
>> >>> +++ testsuite/gcc.target/i386/memcpy-strategy-1.c     (revision 0)
>> >>> @@ -0,0 +1,12 @@
>> >>> +/* { dg-do compile } */
>> >>> +/* { dg-options "-O2 -march=atom -mmemcpy-strategy=vector_loop:-1:align" } */
>> >>> +/* { dg-final { scan-assembler-times "movdqa" 8 { target { ! { ia32 } } } } } */
>> >>> +/* { dg-final { scan-assembler-times "movdqa" 4 { target { ia32 } } } } */
>> >>> +
>> >>> +char a[2048];
>> >>> +char b[2048];
>> >>> +void t (void)
>> >>> +{
>> >>> +  __builtin_memcpy (a, b, 2048);
>> >>> +}
>> >>> +
>> >>> Index: testsuite/gcc.target/i386/memcpy-strategy-2.c
>> >>> ===================================================================
>> >>> --- testsuite/gcc.target/i386/memcpy-strategy-2.c     (revision 0)
>> >>> +++ testsuite/gcc.target/i386/memcpy-strategy-2.c     (revision 0)
>> >>> @@ -0,0 +1,12 @@
>> >>> +/* { dg-do compile } */
>> >>> +/* { dg-options "-O2 -march=atom -mmemcpy-strategy=vector_loop:3000:align,libcall:-1:align" } */
>> >>> +/* { dg-final { scan-assembler-times "movdqa" 8 { target { ! { ia32 } } } } } */
>> >>> +/* { dg-final { scan-assembler-times "movdqa" 4 { target { ia32 } } } } */
>> >>> +
>> >>> +char a[2048];
>> >>> +char b[2048];
>> >>> +void t (void)
>> >>> +{
>> >>> +  __builtin_memcpy (a, b, 2048);
>> >>> +}
>> >>> +
>> >>> Index: testsuite/gcc.target/i386/memset-strategy-1.c
>> >>> ===================================================================
>> >>> --- testsuite/gcc.target/i386/memset-strategy-1.c     (revision 0)
>> >>> +++ testsuite/gcc.target/i386/memset-strategy-1.c     (revision 0)
>> >>> @@ -0,0 +1,10 @@
>> >>> +/* { dg-do compile } */
>> >>> +/* { dg-options "-O2 -march=atom -mmemset-strategy=libcall:-1:align" } */
>> >>> +/* { dg-final { scan-assembler-times "memset" 2  } } */
>> >>> +
>> >>> +char a[2048];
>> >>> +void t (void)
>> >>> +{
>> >>> +  __builtin_memset (a, 1, 2048);
>> >>> +}
>> >>> +
>> >>> Index: testsuite/gcc.target/i386/memcpy-strategy-3.c
>> >>> ===================================================================
>> >>> --- testsuite/gcc.target/i386/memcpy-strategy-3.c     (revision 0)
>> >>> +++ testsuite/gcc.target/i386/memcpy-strategy-3.c     (revision 0)
>> >>> @@ -0,0 +1,11 @@
>> >>> +/* { dg-do compile } */
>> >>> +/* { dg-options "-O2 -march=atom -mmemcpy-strategy=vector_loop:2000:align,libcall:-1:align" } */
>> >>> +/* { dg-final { scan-assembler-times "memcpy" 2  } } */
>> >>> +
>> >>> +char a[2048];
>> >>> +char b[2048];
>> >>> +void t (void)
>> >>> +{
>> >>> +  __builtin_memcpy (a, b, 2048);
>> >>> +}
>> >>> +
>> >>
>>
>>
>>
>> --
>> ---
>> Best regards,
>> Michael V. Zolotukhin,
>> Software Engineer
>> Intel Corporation.
Joseph S. Myers - Aug. 8, 2013, 12:23 a.m.
On Wed, 7 Aug 2013, Xinliang David Li wrote:

> Index: config/i386/stringop.def
> ===================================================================
> --- config/i386/stringop.def	(revision 0)
> +++ config/i386/stringop.def	(revision 0)
> @@ -0,0 +1,42 @@
> +/* Definitions for option handling for IA-32.
> +   Copyright (C) 2013 Free Software Foundation, Inc.
> +
> +This file is part of GCC.
> +
> +GCC is free software; you can redistribute it and/or modify
> +it under the terms of the GNU General Public License as published by
> +the Free Software Foundation; either version 3, or (at your option)
> +any later version.
> +
> +GCC is distributed in the hope that it will be useful,
> +but WITHOUT ANY WARRANTY; without even the implied warranty of
> +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +GNU General Public License for more details.
> +
> +Under Section 7 of GPL version 3, you are granted additional
> +permissions described in the GCC Runtime Library Exception, version
> +3.1, as published by the Free Software Foundation.

Why the exception?  This should only be used on the host, not the target.

> +  do
> +    {
> +      int mins, maxs;
> +      stringop_alg alg;
> +      char alg_name[128];
> +      char align[16];
> +
> +      next_range_str = strchr (curr_range_str, ',');
> +      if (next_range_str)
> +        *next_range_str++ = '\0';
> +
> +      if (3 != sscanf (curr_range_str, "%[^:]:%d:%s", alg_name, &maxs, align))

This appears to introduce buffer overruns, which is never OK - whatever 
the length of strings in the command-line arguments, you must not overflow 
fixed-width buffers, so you must specify maximum field widths for the %[] 
and %s.

> +        {
> +          warning (0, "Wrong arg %s to option %s", curr_range_str,
> +                   is_memset ? "-mmemset_strategy=" : "-mmemcpy_strategy=");
> +          return;

Invalid option arguments should be errors, not warnings, and diagnostics 
should not start with a capital letter.  Same applies to other diagnostics 
here.

> Index: config/i386/stringop.opt
> ===================================================================
> --- config/i386/stringop.opt	(revision 0)
> +++ config/i386/stringop.opt	(revision 0)
> @@ -0,0 +1,36 @@
> +/* Definitions for option handling for IA-32.
> +   Copyright (C) 2013 Free Software Foundation, Inc.
> +
> +This file is part of GCC.
> +
> +GCC is free software; you can redistribute it and/or modify
> +it under the terms of the GNU General Public License as published by
> +the Free Software Foundation; either version 3, or (at your option)
> +any later version.
> +
> +GCC is distributed in the hope that it will be useful,
> +but WITHOUT ANY WARRANTY; without even the implied warranty of
> +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +GNU General Public License for more details.
> +
> +Under Section 7 of GPL version 3, you are granted additional
> +permissions described in the GCC Runtime Library Exception, version
> +3.1, as published by the Free Software Foundation.

Again, why the exception?
Xinliang David Li - Aug. 8, 2013, 12:29 a.m.
On Wed, Aug 7, 2013 at 5:23 PM, Joseph S. Myers <joseph@codesourcery.com> wrote:
> On Wed, 7 Aug 2013, Xinliang David Li wrote:
>
>> Index: config/i386/stringop.def
>> ===================================================================
>> --- config/i386/stringop.def  (revision 0)
>> +++ config/i386/stringop.def  (revision 0)
>> @@ -0,0 +1,42 @@
>> +/* Definitions for option handling for IA-32.
>> +   Copyright (C) 2013 Free Software Foundation, Inc.
>> +
>> +This file is part of GCC.
>> +
>> +GCC is free software; you can redistribute it and/or modify
>> +it under the terms of the GNU General Public License as published by
>> +the Free Software Foundation; either version 3, or (at your option)
>> +any later version.
>> +
>> +GCC is distributed in the hope that it will be useful,
>> +but WITHOUT ANY WARRANTY; without even the implied warranty of
>> +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> +GNU General Public License for more details.
>> +
>> +Under Section 7 of GPL version 3, you are granted additional
>> +permissions described in the GCC Runtime Library Exception, version
>> +3.1, as published by the Free Software Foundation.
>
> Why the exception?  This should only be used on the host, not the target.


Sorry, I copied the boiler-plate header from i386.h -- is it wrong there too?


>
>> +  do
>> +    {
>> +      int mins, maxs;
>> +      stringop_alg alg;
>> +      char alg_name[128];
>> +      char align[16];
>> +
>> +      next_range_str = strchr (curr_range_str, ',');
>> +      if (next_range_str)
>> +        *next_range_str++ = '\0';
>> +
>> +      if (3 != sscanf (curr_range_str, "%[^:]:%d:%s", alg_name, &maxs, align))
>
> This appears to introduce buffer overruns, which is never OK - whatever
> the length of strings in the command-line arguments, you must not overflow
> fixed-width buffers, so you must specify maximum field widths for the %[]
> and %s.
>

Ok will fix.


>> +        {
>> +          warning (0, "Wrong arg %s to option %s", curr_range_str,
>> +                   is_memset ? "-mmemset_strategy=" : "-mmemcpy_strategy=");
>> +          return;
>
> Invalid option arguments should be errors, not warnings, and diagnostics
> should not start with a capital letter.  Same applies to other diagnostics
> here.
>

Ok will fix.


>> Index: config/i386/stringop.opt
>> ===================================================================
>> --- config/i386/stringop.opt  (revision 0)
>> +++ config/i386/stringop.opt  (revision 0)
>> @@ -0,0 +1,36 @@
>> +/* Definitions for option handling for IA-32.
>> +   Copyright (C) 2013 Free Software Foundation, Inc.
>> +
>> +This file is part of GCC.
>> +
>> +GCC is free software; you can redistribute it and/or modify
>> +it under the terms of the GNU General Public License as published by
>> +the Free Software Foundation; either version 3, or (at your option)
>> +any later version.
>> +
>> +GCC is distributed in the hope that it will be useful,
>> +but WITHOUT ANY WARRANTY; without even the implied warranty of
>> +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> +GNU General Public License for more details.
>> +
>> +Under Section 7 of GPL version 3, you are granted additional
>> +permissions described in the GCC Runtime Library Exception, version
>> +3.1, as published by the Free Software Foundation.
>
> Again, why the exception?

Wrong template used.

thanks,

David

>
> --
> Joseph S. Myers
> joseph@codesourcery.com
Joseph S. Myers - Aug. 8, 2013, 1:04 a.m.
On Wed, 7 Aug 2013, Xinliang David Li wrote:

> > Why the exception?  This should only be used on the host, not the target.
> 
> Sorry, I copied the boiler-plate header from i386.h -- is it wrong there too?

tm.h gets included in target code because we haven't finished separating 
target macros used on the target from those used on the host.

Patch

Index: testsuite/gcc.target/i386/memcpy-strategy-3.c
===================================================================
--- testsuite/gcc.target/i386/memcpy-strategy-3.c	(revision 0)
+++ testsuite/gcc.target/i386/memcpy-strategy-3.c	(revision 0)
@@ -0,0 +1,11 @@ 
+/* { dg-do compile } */
+/* { dg-options "-O2 -march=atom -mmemcpy-strategy=vector_loop:2000:align,libcall:-1:align" } */
+/* { dg-final { scan-assembler-times "memcpy" 2  } } */
+
+char a[2048];
+char b[2048];
+void t (void)
+{
+  __builtin_memcpy (a, b, 2048);
+}
+
Index: testsuite/gcc.target/i386/memcpy-strategy-1.c
===================================================================
--- testsuite/gcc.target/i386/memcpy-strategy-1.c	(revision 0)
+++ testsuite/gcc.target/i386/memcpy-strategy-1.c	(revision 0)
@@ -0,0 +1,12 @@ 
+/* { dg-do compile } */
+/* { dg-options "-O2 -march=atom -mmemcpy-strategy=vector_loop:-1:align" } */
+/* { dg-final { scan-assembler-times "movdqa" 8 { target { ! { ia32 } } } } } */
+/* { dg-final { scan-assembler-times "movdqa" 4 { target { ia32 } } } } */
+
+char a[2048];
+char b[2048];
+void t (void)
+{
+  __builtin_memcpy (a, b, 2048);
+}
+
Index: testsuite/gcc.target/i386/memcpy-strategy-2.c
===================================================================
--- testsuite/gcc.target/i386/memcpy-strategy-2.c	(revision 0)
+++ testsuite/gcc.target/i386/memcpy-strategy-2.c	(revision 0)
@@ -0,0 +1,12 @@ 
+/* { dg-do compile } */
+/* { dg-options "-O2 -march=atom -mmemcpy-strategy=vector_loop:3000:align,libcall:-1:align" } */
+/* { dg-final { scan-assembler-times "movdqa" 8 { target { ! { ia32 } } } } } */
+/* { dg-final { scan-assembler-times "movdqa" 4 { target { ia32 } } } } */
+
+char a[2048];
+char b[2048];
+void t (void)
+{
+  __builtin_memcpy (a, b, 2048);
+}
+
Index: testsuite/gcc.target/i386/memset-strategy-1.c
===================================================================
--- testsuite/gcc.target/i386/memset-strategy-1.c	(revision 0)
+++ testsuite/gcc.target/i386/memset-strategy-1.c	(revision 0)
@@ -0,0 +1,10 @@ 
+/* { dg-do compile } */
+/* { dg-options "-O2 -march=atom -mmemset-strategy=libcall:-1:align" } */
+/* { dg-final { scan-assembler-times "memset" 2  } } */
+
+char a[2048];
+void t (void)
+{
+  __builtin_memset (a, 1, 2048);
+}
+
Index: doc/invoke.texi
===================================================================
--- doc/invoke.texi	(revision 201540)
+++ doc/invoke.texi	(working copy)
@@ -649,6 +649,7 @@  Objective-C and Objective-C++ Dialects}.
 -mbmi2 -mrtm -mlwp -mthreads @gol
 -mno-align-stringops  -minline-all-stringops @gol
 -minline-stringops-dynamically -mstringop-strategy=@var{alg} @gol
+-mmemcpy-strategy=@var{strategy} -mmemset-strategy=@var{strategy} 
 -mpush-args  -maccumulate-outgoing-args  -m128bit-long-double @gol
 -m96bit-long-double -mlong-double-64 -mlong-double-80 @gol
 -mregparm=@var{num}  -msseregparm @gol
@@ -14598,6 +14599,24 @@  Expand into an inline loop.
 Always use a library call.
 @end table
 
+@item -mmemcpy-strategy=@var{strategy}
+@opindex mmemcpy-strategy=@var{strategy}
+Override the internal decision heuristic to decide if @code{__builtin_memcpy}
+should be inlined and what inline algorithm to use when the expected size
+of the copy operation is known. @var{strategy} 
+is a comma-separated list of @var{alg}:@var{max_size}:@var{dest_align} triplets. 
+@var{alg} is specified in @option{-mstringop-strategy}, @var{max_size} specifies
+the max byte size with which inline algorithm @var{alg} is allowed.  For the last
+triplet, the @var{max_size} must be @code{-1}. The @var{max_size} of the triplets
+in the list must be specified in increasing order.  The minimal byte size for 
+@var{alg} is @code{0} for the first triplet and @code{@var{max_size} + 1} of the 
+preceding range.
+
+@item -mmemset-strategy=@var{strategy}
+@opindex mmemset-strategy=@var{strategy}
+The option is similar to @option{-mmemcpy-strategy=} except that it is to control
+@code{__builtin_memset} expansion.
+
 @item -momit-leaf-frame-pointer
 @opindex momit-leaf-frame-pointer
 Don't keep the frame pointer in a register for leaf functions.  This
Index: config/i386/stringop.def
===================================================================
--- config/i386/stringop.def	(revision 0)
+++ config/i386/stringop.def	(revision 0)
@@ -0,0 +1,42 @@ 
+/* Definitions for option handling for IA-32.
+   Copyright (C) 2013 Free Software Foundation, Inc.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 3, or (at your option)
+any later version.
+
+GCC is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+Under Section 7 of GPL version 3, you are granted additional
+permissions described in the GCC Runtime Library Exception, version
+3.1, as published by the Free Software Foundation.
+
+You should have received a copy of the GNU General Public License and
+a copy of the GCC Runtime Library Exception along with this program;
+see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+<http://www.gnu.org/licenses/>.  */
+
+DEF_ENUM
+DEF_ALG (no_stringop, no_stringop)
+DEF_ENUM
+DEF_ALG (libcall, libcall)
+DEF_ENUM
+DEF_ALG (rep_prefix_1_byte, rep_byte)
+DEF_ENUM
+DEF_ALG (rep_prefix_4_byte, rep_4byte)
+DEF_ENUM
+DEF_ALG (rep_prefix_8_byte, rep_8byte)
+DEF_ENUM
+DEF_ALG (loop_1_byte, byte_loop)
+DEF_ENUM
+DEF_ALG (loop, loop)
+DEF_ENUM
+DEF_ALG (unrolled_loop, unrolled_loop)
+DEF_ENUM
+DEF_ALG (vector_loop, vector_loop)
Index: config/i386/i386.c
===================================================================
--- config/i386/i386.c	(revision 201540)
+++ config/i386/i386.c	(working copy)
@@ -158,7 +158,7 @@  struct processor_costs ix86_size_cost =
 };
 
 /* Processor costs (relative to an add) */
-static const
+static
 struct processor_costs i386_cost = {	/* 386 specific costs */
   COSTS_N_INSNS (1),			/* cost of an add instruction */
   COSTS_N_INSNS (1),			/* cost of a lea instruction */
@@ -228,7 +228,7 @@  struct processor_costs i386_cost = {	/*
   1,					/* cond_not_taken_branch_cost.  */
 };
 
-static const
+static
 struct processor_costs i486_cost = {	/* 486 specific costs */
   COSTS_N_INSNS (1),			/* cost of an add instruction */
   COSTS_N_INSNS (1),			/* cost of a lea instruction */
@@ -300,7 +300,7 @@  struct processor_costs i486_cost = {	/*
   1,					/* cond_not_taken_branch_cost.  */
 };
 
-static const
+static
 struct processor_costs pentium_cost = {
   COSTS_N_INSNS (1),			/* cost of an add instruction */
   COSTS_N_INSNS (1),			/* cost of a lea instruction */
@@ -370,7 +370,7 @@  struct processor_costs pentium_cost = {
   1,					/* cond_not_taken_branch_cost.  */
 };
 
-static const
+static
 struct processor_costs pentiumpro_cost = {
   COSTS_N_INSNS (1),			/* cost of an add instruction */
   COSTS_N_INSNS (1),			/* cost of a lea instruction */
@@ -449,7 +449,7 @@  struct processor_costs pentiumpro_cost =
   1,					/* cond_not_taken_branch_cost.  */
 };
 
-static const
+static
 struct processor_costs geode_cost = {
   COSTS_N_INSNS (1),			/* cost of an add instruction */
   COSTS_N_INSNS (1),			/* cost of a lea instruction */
@@ -520,7 +520,7 @@  struct processor_costs geode_cost = {
   1,					/* cond_not_taken_branch_cost.  */
 };
 
-static const
+static
 struct processor_costs k6_cost = {
   COSTS_N_INSNS (1),			/* cost of an add instruction */
   COSTS_N_INSNS (2),			/* cost of a lea instruction */
@@ -593,7 +593,7 @@  struct processor_costs k6_cost = {
   1,					/* cond_not_taken_branch_cost.  */
 };
 
-static const
+static
 struct processor_costs athlon_cost = {
   COSTS_N_INSNS (1),			/* cost of an add instruction */
   COSTS_N_INSNS (2),			/* cost of a lea instruction */
@@ -666,7 +666,7 @@  struct processor_costs athlon_cost = {
   1,					/* cond_not_taken_branch_cost.  */
 };
 
-static const
+static
 struct processor_costs k8_cost = {
   COSTS_N_INSNS (1),			/* cost of an add instruction */
   COSTS_N_INSNS (2),			/* cost of a lea instruction */
@@ -1267,7 +1267,7 @@  struct processor_costs btver2_cost = {
   1,					/* cond_not_taken_branch_cost.  */
 };
 
-static const
+static
 struct processor_costs pentium4_cost = {
   COSTS_N_INSNS (1),			/* cost of an add instruction */
   COSTS_N_INSNS (3),			/* cost of a lea instruction */
@@ -1338,7 +1338,7 @@  struct processor_costs pentium4_cost = {
   1,					/* cond_not_taken_branch_cost.  */
 };
 
-static const
+static
 struct processor_costs nocona_cost = {
   COSTS_N_INSNS (1),			/* cost of an add instruction */
   COSTS_N_INSNS (1),			/* cost of a lea instruction */
@@ -1411,7 +1411,7 @@  struct processor_costs nocona_cost = {
   1,					/* cond_not_taken_branch_cost.  */
 };
 
-static const
+static
 struct processor_costs atom_cost = {
   COSTS_N_INSNS (1),			/* cost of an add instruction */
   COSTS_N_INSNS (1) + 1,		/* cost of a lea instruction */
@@ -1558,7 +1558,7 @@  struct processor_costs slm_cost = {
 };
 
 /* Generic64 should produce code tuned for Nocona and K8.  */
-static const
+static
 struct processor_costs generic64_cost = {
   COSTS_N_INSNS (1),			/* cost of an add instruction */
   /* On all chips taken into consideration lea is 2 cycles and more.  With
@@ -1637,7 +1637,7 @@  struct processor_costs generic64_cost =
 };
 
 /* core_cost should produce code tuned for Core familly of CPUs.  */
-static const
+static
 struct processor_costs core_cost = {
   COSTS_N_INSNS (1),			/* cost of an add instruction */
   /* On all chips taken into consideration lea is 2 cycles and more.  With
@@ -1719,7 +1719,7 @@  struct processor_costs core_cost = {
 
 /* Generic32 should produce code tuned for PPro, Pentium4, Nocona,
    Athlon and K8.  */
-static const
+static
 struct processor_costs generic32_cost = {
   COSTS_N_INSNS (1),			/* cost of an add instruction */
   COSTS_N_INSNS (1) + 1,		/* cost of a lea instruction */
@@ -2919,6 +2919,149 @@  ix86_debug_options (void)
 
   return;
 }
+
+static const char *stringop_alg_names[] = {
+#define DEF_ENUM
+#define DEF_ALG(alg, name) #name,
+#include "stringop.def"
+#undef DEF_ENUM
+#undef DEF_ALG
+};
+
+/* Parse parameter string passed to -mmemcpy-strategy= or -mmemset-strategy=.
+   The string is of the following form (or comma separated list of it):
+
+     strategy_alg:max_size:[align|noalign]
+
+   where the full size range for the strategy is either [0, max_size] or
+   [min_size, max_size], in which min_size is the max_size + 1 of the
+   preceding range.  The last size range must have max_size == -1.
+
+   Examples:
+
+    1.
+       -mmemcpy-strategy=libcall:-1:noalign
+
+      this is equivalent to (for known size memcpy) -mstringop-strategy=libcall
+
+
+   2.
+      -mmemset-strategy=rep_8byte:16:noalign,vector_loop:2048:align,libcall:-1:noalign
+
+      This is to tell the compiler to use the following strategy for memset
+      1) when the expected size is between [1, 16], use rep_8byte strategy;
+      2) when the size is between [17, 2048], use vector_loop;
+      3) when the size is > 2048, use libcall.  */
+
+struct stringop_size_range
+{
+  int min;
+  int max;
+  stringop_alg alg;
+  bool noalign;
+};
+
+static void
+ix86_parse_stringop_strategy_string (char *strategy_str, bool is_memset)
+{
+  const struct stringop_algs *default_algs;
+  stringop_size_range input_ranges[MAX_STRINGOP_ALGS];
+  char *curr_range_str, *next_range_str;
+  int i = 0, n = 0;
+
+  if (is_memset)
+    default_algs = &ix86_cost->memset[TARGET_64BIT != 0];
+  else
+    default_algs = &ix86_cost->memcpy[TARGET_64BIT != 0];
+
+  curr_range_str = strategy_str;
+
+  do
+    {
+      int mins, maxs;
+      stringop_alg alg;
+      char alg_name[128];
+      char align[16];
+
+      next_range_str = strchr (curr_range_str, ',');
+      if (next_range_str)
+        *next_range_str++ = '\0';
+
+      if (3 != sscanf (curr_range_str, "%[^:]:%d:%s", alg_name, &maxs, align))
+        {
+          warning (0, "Wrong arg %s to option %s", curr_range_str,
+                   is_memset ? "-mmemset_strategy=" : "-mmemcpy_strategy=");
+          return;
+        }
+
+      if (n > 0 && (maxs < (mins = input_ranges[n - 1].max + 1) && maxs != -1))
+        {
+          warning (0, "Size ranges of option %s should be increasing",
+                   is_memset ? "-mmemset_strategy=" : "-mmemcpy_strategy=");
+          return;
+        }
+
+      for (i = 0; i < last_alg; i++)
+        {
+          if (!strcmp (alg_name, stringop_alg_names[i]))
+            {
+              alg = (stringop_alg) i;
+              break;
+            }
+        }
+
+      if (i == last_alg)
+        {
+          warning (0, "Wrong stringop strategy name %s specified for option %s",
+                   alg_name,
+                   is_memset ? "-mmemset_strategy=" : "-mmemcpy_strategy=");
+          return;
+        }
+
+      input_ranges[n].min = mins;
+      input_ranges[n].max = maxs;
+      input_ranges[n].alg = alg;
+      if (!strcmp (align, "align"))
+        input_ranges[n].noalign = false;
+      else if (!strcmp (align, "noalign"))
+        input_ranges[n].noalign = true;
+      else
+        {
+          warning (0, "Unknown alignment %s specified for option %s",
+                   align, is_memset ? "-mmemset_strategy=" : "-mmemcpy_strategy=");
+          return;
+        }
+      n++;
+      curr_range_str = next_range_str;
+    }
+  while (curr_range_str);
+
+  if (input_ranges[n - 1].max != -1)
+    {
+      warning (0, "The max value for the last size range should be -1"
+               " for option %s",
+               is_memset ? "-mmemset_strategy=" : "-mmemcpy_strategy=");
+      return;
+    }
+
+  if (n > MAX_STRINGOP_ALGS)
+    {
+      warning (0, "Too many size ranges specified in option %s",
+               is_memset ? "-mmemset_strategy=" : "-mmemcpy_strategy=");
+      return;
+    }
+
+  /* Now override the default algs array.  */
+  for (i = 0; i < n; i++)
+    {
+      *const_cast<int *>(&default_algs->size[i].max) = input_ranges[i].max;
+      *const_cast<stringop_alg *>(&default_algs->size[i].alg)
+          = input_ranges[i].alg;
+      *const_cast<int *>(&default_algs->size[i].noalign)
+          = input_ranges[i].noalign;
+    }
+}
+
 
 /* Override various settings based on options.  If MAIN_ARGS_P, the
    options are from the command line, otherwise they are from
@@ -4040,6 +4183,21 @@  ix86_option_override_internal (bool main
   /* Handle stack protector */
   if (!global_options_set.x_ix86_stack_protector_guard)
     ix86_stack_protector_guard = TARGET_HAS_BIONIC ? SSP_GLOBAL : SSP_TLS;
+
+  /* Handle -mmemcpy-strategy= and -mmemset-strategy=  */
+  if (ix86_tune_memcpy_strategy)
+    {
+      char *str = xstrdup (ix86_tune_memcpy_strategy);
+      ix86_parse_stringop_strategy_string (str, false);
+      free (str);
+    }
+
+  if (ix86_tune_memset_strategy)
+    {
+      char *str = xstrdup (ix86_tune_memset_strategy);
+      ix86_parse_stringop_strategy_string (str, true);
+      free (str);
+    }
 }
 
 /* Implement the TARGET_OPTION_OVERRIDE hook.  */
@@ -22923,6 +23081,7 @@  ix86_expand_movmem (rtx dst, rtx src, rt
     {
     case libcall:
     case no_stringop:
+    case last_alg:
       gcc_unreachable ();
     case loop_1_byte:
       need_zero_guard = true;
@@ -23113,6 +23272,7 @@  ix86_expand_movmem (rtx dst, rtx src, rt
     {
     case libcall:
     case no_stringop:
+    case last_alg:
       gcc_unreachable ();
     case loop_1_byte:
     case loop:
@@ -23324,6 +23484,7 @@  ix86_expand_setmem (rtx dst, rtx count_e
     {
     case libcall:
     case no_stringop:
+    case last_alg:
       gcc_unreachable ();
     case loop:
       need_zero_guard = true;
@@ -23501,6 +23662,7 @@  ix86_expand_setmem (rtx dst, rtx count_e
     {
     case libcall:
     case no_stringop:
+    case last_alg:
       gcc_unreachable ();
     case loop_1_byte:
     case loop:
Index: config/i386/i386-opts.h
===================================================================
--- config/i386/i386-opts.h	(revision 201540)
+++ config/i386/i386-opts.h	(working copy)
@@ -28,15 +28,17 @@  see the files COPYING3 and COPYING.RUNTI
 /* Algorithm to expand string function with.  */
 enum stringop_alg
 {
-   no_stringop,
-   libcall,
-   rep_prefix_1_byte,
-   rep_prefix_4_byte,
-   rep_prefix_8_byte,
-   loop_1_byte,
-   loop,
-   unrolled_loop,
-   vector_loop
+#undef DEF_ENUM
+#define DEF_ENUM
+
+#undef DEF_ALG
+#define DEF_ALG(alg, name) alg, 
+
+#include "stringop.def"
+last_alg
+
+#undef DEF_ENUM
+#undef DEF_ALG
 };
 
 /* Available call abi.  */
Index: config/i386/stringop.opt
===================================================================
--- config/i386/stringop.opt	(revision 0)
+++ config/i386/stringop.opt	(revision 0)
@@ -0,0 +1,36 @@ 
+/* Definitions for option handling for IA-32.
+   Copyright (C) 2013 Free Software Foundation, Inc.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 3, or (at your option)
+any later version.
+
+GCC is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+Under Section 7 of GPL version 3, you are granted additional
+permissions described in the GCC Runtime Library Exception, version
+3.1, as published by the Free Software Foundation.
+
+You should have received a copy of the GNU General Public License and
+a copy of the GCC Runtime Library Exception along with this program;
+see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+<http://www.gnu.org/licenses/>.  */
+
+Enum(stringop_alg) String(rep_byte) Value(rep_prefix_1_byte)
+
+#undef DEF_ENUM
+#define DEF_ENUM EnumValue
+
+#undef DEF_ALG
+#define DEF_ALG(alg, name) Enum(stringop_alg) String(name) Value(alg)
+
+#include "stringop.def"
+
+#undef DEF_ENUM
+#undef DEF_ALG
Index: config/i386/i386.opt
===================================================================
--- config/i386/i386.opt	(revision 201540)
+++ config/i386/i386.opt	(working copy)
@@ -316,6 +316,14 @@  mstack-arg-probe
 Target Report Mask(STACK_PROBE) Save
 Enable stack probing
 
+mmemcpy-strategy=
+Target RejectNegative Joined Var(ix86_tune_memcpy_strategy)
+Specify memcpy expansion strategy when expected size is known
+
+mmemset-strategy=
+Target RejectNegative Joined Var(ix86_tune_memset_strategy)
+Specify memset expansion strategy when expected size is known
+
 mstringop-strategy=
 Target RejectNegative Joined Enum(stringop_alg) Var(ix86_stringop_alg) Init(no_stringop)
 Chose strategy to generate stringop using