Re: [PATCH] Fix stpcpy and mempcpy expansion (PR middle-end/38343)

["Richard Guenther" <richard dot guenther at gmail dot com>]

On Mon, Dec 1, 2008 at 8:30 PM, Jakub Jelinek <jakub@redhat.com> wrote:
> Hi!
>
> build_call_expr folds it and for memcpy (and strcpy) COMPOUND_EXPRs
> (and for strcpy also NOP_EXPRs around it) can be returned.  Many
> other routines in builtins.c handle these, but expand_builtin_stpcpy
> and expand_builtin_mempcpy_args do not.
> This patch fixes it, as well as folds stpcpy early if the return value
> is known to be ignored earlier than during expansion.
>
> Bootstrapped/regtested on x86_64-linux, ok for trunk?

Ok.

Thanks,
Richard.

> 2008-12-01  Jakub Jelinek  <jakub@redhat.com>
>
>        PR middle-end/38343
>        * builtins.c (expand_builtin_mempcpy_args): Handle COMPOUND_EXPRs
>        potentially returned from folding memcpy.
>        (expand_builtin_stpcpy_args): Similarly for folding strcpy.
>        (fold_builtin_2): Handle BUILT_IN_STPCPY if result is ignored.
>
>        * gcc.c-torture/compile/pr38343.c: New test.
>
> --- gcc/builtins.c.jj   2008-12-01 18:09:52.000000000 +0100
> +++ gcc/builtins.c      2008-12-01 18:34:24.000000000 +0100
> @@ -3406,7 +3406,7 @@ expand_builtin_memcpy (tree exp, rtx tar
>    stpcpy.  */
>
>  static rtx
> -expand_builtin_mempcpy(tree exp, rtx target, enum machine_mode mode)
> +expand_builtin_mempcpy (tree exp, rtx target, enum machine_mode mode)
>  {
>   if (!validate_arglist (exp,
>                         POINTER_TYPE, POINTER_TYPE, INTEGER_TYPE, VOID_TYPE))
> @@ -3433,15 +3433,18 @@ expand_builtin_mempcpy_args (tree dest,
>                             rtx target, enum machine_mode mode, int endp)
>  {
>     /* If return value is ignored, transform mempcpy into memcpy.  */
> -  if (target == const0_rtx)
> +  if (target == const0_rtx && implicit_built_in_decls[BUILT_IN_MEMCPY])
>     {
>       tree fn = implicit_built_in_decls[BUILT_IN_MEMCPY];
> +      tree result = build_call_expr (fn, 3, dest, src, len);
>
> -      if (!fn)
> -       return NULL_RTX;
> -
> -      return expand_expr (build_call_expr (fn, 3, dest, src, len),
> -                         target, mode, EXPAND_NORMAL);
> +      while (TREE_CODE (result) == COMPOUND_EXPR)
> +       {
> +         expand_expr (TREE_OPERAND (result, 0), const0_rtx, VOIDmode,
> +                      EXPAND_NORMAL);
> +         result = TREE_OPERAND (result, 1);
> +       }
> +      return expand_expr (result, target, mode, EXPAND_NORMAL);
>     }
>   else
>     {
> @@ -3707,14 +3710,19 @@ expand_builtin_stpcpy (tree exp, rtx tar
>   src = CALL_EXPR_ARG (exp, 1);
>
>   /* If return value is ignored, transform stpcpy into strcpy.  */
> -  if (target == const0_rtx)
> +  if (target == const0_rtx && implicit_built_in_decls[BUILT_IN_STRCPY])
>     {
>       tree fn = implicit_built_in_decls[BUILT_IN_STRCPY];
> -      if (!fn)
> -       return NULL_RTX;
> +      tree result = build_call_expr (fn, 2, dst, src);
>
> -      return expand_expr (build_call_expr (fn, 2, dst, src),
> -                         target, mode, EXPAND_NORMAL);
> +      STRIP_NOPS (result);
> +      while (TREE_CODE (result) == COMPOUND_EXPR)
> +       {
> +         expand_expr (TREE_OPERAND (result, 0), const0_rtx, VOIDmode,
> +                      EXPAND_NORMAL);
> +         result = TREE_OPERAND (result, 1);
> +       }
> +      return expand_expr (result, target, mode, EXPAND_NORMAL);
>     }
>   else
>     {
> @@ -10463,6 +10471,17 @@ fold_builtin_2 (tree fndecl, tree arg0,
>     case BUILT_IN_STRCPY:
>       return fold_builtin_strcpy (fndecl, arg0, arg1, NULL_TREE);
>
> +    case BUILT_IN_STPCPY:
> +      if (ignore)
> +       {
> +         tree fn = implicit_built_in_decls[BUILT_IN_STRCPY];
> +         if (!fn)
> +           break;
> +
> +         return build_call_expr (fn, 2, arg0, arg1);
> +       }
> +      break;
> +
>     case BUILT_IN_STRCMP:
>       return fold_builtin_strcmp (arg0, arg1);
>
> --- gcc/testsuite/gcc.c-torture/compile/pr38343.c.jj    2008-12-01 18:36:44.000000000 +0100
> +++ gcc/testsuite/gcc.c-torture/compile/pr38343.c       2008-12-01 18:36:25.000000000 +0100
> @@ -0,0 +1,12 @@
> +/* PR middle-end/38343 */
> +
> +static struct A
> +{
> +  char f[6];
> +} a[] = { {"01000"} };
> +
> +void
> +foo (void)
> +{
> +  __builtin_stpcpy (a[0].f, "S0022");
> +}
>
>        Jakub
>