On Thu, 23 Nov 2017, Jakub Jelinek wrote:
> Hi!
>
> As mentioned on IRC, we can actually now use ERF_RETURN*_ARG* to find out
> what functions are pass through (except for __builtin_assume_aligned, which
> is pass through but we never want to propagate the arg to the result early, as
> the result contains additional information, so it isn't RET1).
>
> While cleaning this up, I run into a bug in the function, BUILT_IN_STPNCPY_CHK
> obviously isn't a pass-through function, so I've also added a testcase that
> FAILs without this patch and succeeds with it.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
Ok.
Thanks,
Richard.
> For release branches I'd just remove the BUILT_IN_STPNCPY_CHK case and
> add testcase.
>
> 2017-11-23 Jakub Jelinek <ja...@redhat.com>
>
> * tree-object-size.c (pass_through_call): Use gimple_call_return_flags
> ERF_RETURN*ARG* for builtins other than BUILT_IN_ASSUME_ALIGNED,
> check for the latter with gimple_call_builtin_p. Do not handle
> BUILT_IN_STPNCPY_CHK which is not a pass through call.
>
> * gcc.dg/builtin-object-size-18.c: New test.
>
> --- gcc/tree-object-size.c.jj 2017-10-20 09:16:10.000000000 +0200
> +++ gcc/tree-object-size.c 2017-11-23 16:23:24.544741945 +0100
> @@ -464,34 +464,17 @@ alloc_object_size (const gcall *call, in
> static tree
> pass_through_call (const gcall *call)
> {
> - tree callee = gimple_call_fndecl (call);
> + unsigned rf = gimple_call_return_flags (call);
> + if (rf & ERF_RETURNS_ARG)
> + {
> + unsigned argnum = rf & ERF_RETURN_ARG_MASK;
> + if (argnum < gimple_call_num_args (call))
> + return gimple_call_arg (call, argnum);
> + }
>
> - if (callee
> - && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL)
> - switch (DECL_FUNCTION_CODE (callee))
> - {
> - case BUILT_IN_MEMCPY:
> - case BUILT_IN_MEMMOVE:
> - case BUILT_IN_MEMSET:
> - case BUILT_IN_STRCPY:
> - case BUILT_IN_STRNCPY:
> - case BUILT_IN_STRCAT:
> - case BUILT_IN_STRNCAT:
> - case BUILT_IN_MEMCPY_CHK:
> - case BUILT_IN_MEMMOVE_CHK:
> - case BUILT_IN_MEMSET_CHK:
> - case BUILT_IN_STRCPY_CHK:
> - case BUILT_IN_STRNCPY_CHK:
> - case BUILT_IN_STPNCPY_CHK:
> - case BUILT_IN_STRCAT_CHK:
> - case BUILT_IN_STRNCAT_CHK:
> - case BUILT_IN_ASSUME_ALIGNED:
> - if (gimple_call_num_args (call) >= 1)
> - return gimple_call_arg (call, 0);
> - break;
> - default:
> - break;
> - }
> + /* __builtin_assume_aligned is intentionally not marked RET1. */
> + if (gimple_call_builtin_p (call, BUILT_IN_ASSUME_ALIGNED))
> + return gimple_call_arg (call, 0);
>
> return NULL_TREE;
> }
> --- gcc/testsuite/gcc.dg/builtin-object-size-18.c.jj 2017-11-23
> 16:33:25.723389685 +0100
> +++ gcc/testsuite/gcc.dg/builtin-object-size-18.c 2017-11-23
> 16:34:02.930934647 +0100
> @@ -0,0 +1,15 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-tree-optimized" } */
> +/* __stpncpy_chk could return buf up to buf + 64, so
> + the minimum object size might be far smaller than 64. */
> +/* { dg-final { scan-tree-dump-not "return 64;" "optimized" } } */
> +
> +typedef __SIZE_TYPE__ size_t;
> +
> +size_t
> +foo (const char *p, size_t s, size_t t)
> +{
> + char buf[64];
> + char *q = __builtin___stpncpy_chk (buf, p, s, t);
> + return __builtin_object_size (q, 2);
> +}
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB
21284 (AG Nuernberg)
