Re: builtin ffs vs. renamed ffs (vms-crtl.h)

[Andrew Pinski <pinskia at gmail dot com>]

Sent from my iPhone

On May 7, 2010, at 11:20 PM, Jay K <jay.krell@cornell.edu> wrote:

> In gcc for VMS there is some mechanism to rename functions.
> See the files:
>
> /src/gcc-4.5.0/gcc/config/vms/vms-crtl-64.h
> /src/gcc-4.5.0/gcc/config/vms/vms-crtl.h
>
>
> which are mostly just lists of function from/to.
>
>
> As well in gcc there is a mechanism for optimizing various "builtin"  
> functions, like ffs.

For builtins you should look at how PowerPC Darwin handles the long  
double builtins since they are renamed if long double is 128bit.

Thanks,
Andrew Pinski


> These two mechanisms seem to conflict or be applied in the wrong  
> order.
> I didn't look at it deeply.
>
>
> The symptom is that if you add ffs (to decc$ffs) to vms-crtl.h, the  
> translation
> is not done, and you end up with unresolved external ffs.
>
>
> If you #if out the support for "builtin ffs", it works.
>
>
> My local hack is below but obviously that's not the way.
>
>
> I'll enter a bug.
>
>
> Thanks,
>  - Jay
>
>
> diff -u /src/orig/gcc-4.5.0/gcc/builtins.c ./builtins.c
> --- /src/orig/gcc-4.5.0/gcc/builtins.c    2010-04-13 06:47:11.000000000 
>  -0700
> +++ ./builtins.c    2010-05-07 23:11:30.000000000 -0700
> @@ -51,6 +51,8 @@
>  #include "value-prof.h"
>  #include "diagnostic.h"
>
> +#define DISABLE_FFS
> +
>  #ifndef SLOW_UNALIGNED_ACCESS
>  #define SLOW_UNALIGNED_ACCESS(MODE, ALIGN) STRICT_ALIGNMENT
>  #endif
> @@ -5899,6 +5901,7 @@
>      return target;
>        break;
>
> +#ifndef DISABLE_FFS
>      CASE_INT_FN (BUILT_IN_FFS):
>      case BUILT_IN_FFSIMAX:
>        target = expand_builtin_unop (target_mode, exp, target,
> @@ -5906,6 +5909,7 @@
>        if (target)
>      return target;
>        break;
> +#endif
>
>      CASE_INT_FN (BUILT_IN_CLZ):
>      case BUILT_IN_CLZIMAX:
> @@ -13612,6 +13616,7 @@
>      case BUILT_IN_ABORT:
>        abort_libfunc = set_user_assembler_libfunc ("abort", asmspec);
>        break;
> +#ifndef DISABLE_FFS
>      case BUILT_IN_FFS:
>        if (INT_TYPE_SIZE < BITS_PER_WORD)
>      {
> @@ -13620,6 +13625,7 @@
>                                 MODE_INT, 0), "ffs");
>      }
>        break;
> +#endif
>      default:
>        break;
>      }
> diff -u /src/orig/gcc-4.5.0/gcc/optabs.c ./optabs.c
> --- /src/orig/gcc-4.5.0/gcc/optabs.c    2010-03-19  
> 12:45:01.000000000 -0700
> +++ ./optabs.c    2010-05-07 23:11:36.000000000 -0700
> @@ -45,6 +45,8 @@
>  #include "basic-block.h"
>  #include "target.h"
>
> +#define DISABLE_FFS
> +
>  /* Each optab contains info on how this target machine
>     can perform a particular operation
>     for all sizes and kinds of operands.
> @@ -3240,6 +3242,7 @@
>      return temp;
>      }
>
> +#ifndef DISABLE_FFS
>    /* Try implementing ffs (x) in terms of clz (x).  */
>    if (unoptab == ffs_optab)
>      {
> @@ -3247,6 +3250,7 @@
>        if (temp)
>      return temp;
>      }
> +#endif
>
>    /* Try implementing ctz (x) in terms of clz (x).  */
>    if (unoptab == ctz_optab)
> @@ -3268,7 +3272,11 @@
>
>        /* All of these functions return small values.  Thus we  
> choose to
>       have them return something that isn't a double-word.  */
> -      if (unoptab == ffs_optab || unoptab == clz_optab || unoptab  
> == ctz_optab
> +      if (
> +#ifndef DISABLE_FFS
> +      unoptab == ffs_optab ||
> +#endif
> +        unoptab == clz_optab || unoptab == ctz_optab
>        || unoptab == popcount_optab || unoptab == parity_optab)
>      outmode
>        = GET_MODE (hard_libcall_value (TYPE_MODE (integer_type_node),
> @@ -6301,7 +6309,9 @@
>    init_optab (addcc_optab, UNKNOWN);
>    init_optab (one_cmpl_optab, NOT);
>    init_optab (bswap_optab, BSWAP);
> +#ifndef DISABLE_FFS
>    init_optab (ffs_optab, FFS);
> +#endif
>    init_optab (clz_optab, CLZ);
>    init_optab (ctz_optab, CTZ);
>    init_optab (popcount_optab, POPCOUNT);
> @@ -6558,9 +6568,11 @@
>    one_cmpl_optab->libcall_basename = "one_cmpl";
>    one_cmpl_optab->libcall_suffix = '2';
>    one_cmpl_optab->libcall_gen = gen_int_libfunc;
> +#ifndef DISABLE_FFS
>    ffs_optab->libcall_basename = "ffs";
>    ffs_optab->libcall_suffix = '2';
>    ffs_optab->libcall_gen = gen_int_libfunc;
> +#endif
>    clz_optab->libcall_basename = "clz";
>    clz_optab->libcall_suffix = '2';
>    clz_optab->libcall_gen = gen_int_libfunc;
> @@ -6643,11 +6655,13 @@
>    satfractuns_optab->libcall_basename = "satfractuns";
>    satfractuns_optab->libcall_gen = gen_satfractuns_conv_libfunc;
>
> +#ifndef DISABLE_FFS
>    /* The ffs function operates on `int'.  Fall back on it if we do  
> not
>       have a libgcc2 function for that width.  */
>    if (INT_TYPE_SIZE < BITS_PER_WORD)
>      set_optab_libfunc (ffs_optab, mode_for_size (INT_TYPE_SIZE,  
> MODE_INT, 0),
>                 "ffs");
> +#endif
>
>    /* Explicitly initialize the bswap libfuncs since we need them to  
> be
>       valid for things other than word_mode.  */
>
>
> Thanks,
>  - Jay