On Wed, 13 Mar 2019, Jakub Jelinek wrote:
> Hi!
>
> The C FE sadly passes through some really bad prototypes of builtin
> functions as "harmless":
> /* Accept "harmless" mismatches in function types such
> as missing qualifiers or pointer vs same size integer
> mismatches. This is for the ffs and fprintf builtins.
> However, with -Wextra in effect, diagnose return and
> argument types that are incompatible according to
> language rules. */
> In the strlen pass, we'd better have pointers where we expect pointers and
> rightly sized integers where we expect integers. The following patch
> ensures that by calling gimple_builtin_call_types_compatible_p against
> the builtin_decl_explicit decl.
>
> Furthermore, I've noticed that a bunch of later added builtins that
> the strlen pass now handles weren't added to valid_builtin_call, so the
> patch adds that too (that is to handle cases where e.g. somebody declares
> strncat as pure, or strcmp as const etc.).
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
OK.
Richard.
> 2019-03-13 Jakub Jelinek <ja...@redhat.com>
>
> PR tree-optimization/89703
> * tree-ssa-strlen.c (valid_builtin_call): Punt if stmt call types
> aren't compatible also with builtin_decl_explicit. Check pure
> or non-pure status of BUILT_IN_STR{{,N}CMP,N{LEN,{CAT,CPY}{,_CHK}}}
> and BUILT_IN_STPNCPY{,_CHK}.
>
> * gcc.c-torture/compile/pr89703-1.c: New test.
> * gcc.c-torture/compile/pr89703-2.c: New test.
>
> --- gcc/tree-ssa-strlen.c.jj 2019-02-26 21:33:38.992826180 +0100
> +++ gcc/tree-ssa-strlen.c 2019-03-13 19:53:20.152551962 +0100
> @@ -971,12 +971,21 @@ valid_builtin_call (gimple *stmt)
> return false;
>
> tree callee = gimple_call_fndecl (stmt);
> + tree decl = builtin_decl_explicit (DECL_FUNCTION_CODE (callee));
> + if (decl
> + && decl != callee
> + && !gimple_builtin_call_types_compatible_p (stmt, decl))
> + return false;
> +
> switch (DECL_FUNCTION_CODE (callee))
> {
> case BUILT_IN_MEMCMP:
> case BUILT_IN_MEMCMP_EQ:
> + case BUILT_IN_STRCMP:
> + case BUILT_IN_STRNCMP:
> case BUILT_IN_STRCHR:
> case BUILT_IN_STRLEN:
> + case BUILT_IN_STRNLEN:
> /* The above functions should be pure. Punt if they aren't. */
> if (gimple_vdef (stmt) || gimple_vuse (stmt) == NULL_TREE)
> return false;
> @@ -991,10 +1000,16 @@ valid_builtin_call (gimple *stmt)
> case BUILT_IN_MEMSET:
> case BUILT_IN_STPCPY:
> case BUILT_IN_STPCPY_CHK:
> + case BUILT_IN_STPNCPY:
> + case BUILT_IN_STPNCPY_CHK:
> case BUILT_IN_STRCAT:
> case BUILT_IN_STRCAT_CHK:
> case BUILT_IN_STRCPY:
> case BUILT_IN_STRCPY_CHK:
> + case BUILT_IN_STRNCAT:
> + case BUILT_IN_STRNCAT_CHK:
> + case BUILT_IN_STRNCPY:
> + case BUILT_IN_STRNCPY_CHK:
> /* The above functions should be neither const nor pure. Punt if they
> aren't. */
> if (gimple_vdef (stmt) == NULL_TREE || gimple_vuse (stmt) == NULL_TREE)
> --- gcc/testsuite/gcc.c-torture/compile/pr89703-1.c.jj 2019-03-13
> 19:56:10.619785685 +0100
> +++ gcc/testsuite/gcc.c-torture/compile/pr89703-1.c 2019-03-13
> 19:55:48.490146110 +0100
> @@ -0,0 +1,13 @@
> +/* PR tree-optimization/89703 */
> +
> +typedef __SIZE_TYPE__ size_t;
> +extern char *strlen (const char *);
> +extern char *strnlen (const char *, size_t);
> +extern char c[2];
> +
> +void
> +foo (char **q)
> +{
> + q[0] = strlen (c);
> + q[1] = strnlen (c, 2);
> +}
> --- gcc/testsuite/gcc.c-torture/compile/pr89703-2.c.jj 2019-03-13
> 19:56:13.495738838 +0100
> +++ gcc/testsuite/gcc.c-torture/compile/pr89703-2.c 2019-03-13
> 19:55:55.310035032 +0100
> @@ -0,0 +1,13 @@
> +/* PR tree-optimization/89703 */
> +
> +typedef __SIZE_TYPE__ size_t;
> +extern void *memcpy (void *, const void *, size_t);
> +extern char *strlen (const char *);
> +extern char c[2];
> +
> +void
> +foo (char **q)
> +{
> + memcpy (c, "a", 2);
> + q[0] = strlen (c);
> +}
>
> Jakub
>
--
Richard Biener <rguent...@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB
21284 (AG Nuernberg)
