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From: Siddhesh Poyarekar <siddhesh@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org Subject: [gcc r12-7794] tree-optimization/104970: Limit size computation for access attribute Date: Thu, 24 Mar 2022 09:40:52 +0000 (GMT) [thread overview] Message-ID: <20220324094052.364E73858C2C@sourceware.org> (raw) https://gcc.gnu.org/g:c1d233e3334df07cfb4f732ace4d93d3cbc28bca commit r12-7794-gc1d233e3334df07cfb4f732ace4d93d3cbc28bca Author: Siddhesh Poyarekar <siddhesh@gotplt.org> Date: Wed Mar 23 23:09:02 2022 +0530 tree-optimization/104970: Limit size computation for access attribute Limit object size computation only to the simple case where access attribute has been explicitly specified. The object passed to __builtin_dynamic_object_size could either be a pointer or a VLA whose size has been described using access attribute. Further, return a valid size only if the object is a void * pointer or points to (or is a VLA of) a type that has a constant size. gcc/ChangeLog: PR tree-optimization/104970 * tree-object-size.cc (parm_object_size): Restrict size computation scenarios to explicit access attributes. gcc/testsuite/ChangeLog: PR tree-optimization/104970 * gcc.dg/builtin-dynamic-object-size-0.c (test_parmsz_simple2, test_parmsz_simple3, test_parmsz_extern, test_parmsz_internal, test_parmsz_internal2, test_parmsz_internal3): New tests. (main): Use them. Signed-off-by: Siddhesh Poyarekar <siddhesh@gotplt.org> Diff: --- .../gcc.dg/builtin-dynamic-object-size-0.c | 71 ++++++++++++++++++++++ gcc/tree-object-size.cc | 11 +++- 2 files changed, 79 insertions(+), 3 deletions(-) diff --git a/gcc/testsuite/gcc.dg/builtin-dynamic-object-size-0.c b/gcc/testsuite/gcc.dg/builtin-dynamic-object-size-0.c index e5dc23a908d..b5b0b3a677c 100644 --- a/gcc/testsuite/gcc.dg/builtin-dynamic-object-size-0.c +++ b/gcc/testsuite/gcc.dg/builtin-dynamic-object-size-0.c @@ -380,6 +380,22 @@ test_parmsz_simple (void *obj, size_t sz) return __builtin_dynamic_object_size (obj, 0); } +size_t +__attribute__ ((access (__read_write__, 2, 1))) +__attribute__ ((noinline)) +test_parmsz_simple2 (size_t sz, char obj[]) +{ + return __builtin_dynamic_object_size (obj, 0); +} + +/* Implicitly constructed access attributes not supported yet. */ +size_t +__attribute__ ((noinline)) +test_parmsz_simple3 (size_t sz, char obj[sz]) +{ + return __builtin_dynamic_object_size (obj, 0); +} + size_t __attribute__ ((noinline)) __attribute__ ((access (__read_write__, 1, 2))) @@ -412,6 +428,38 @@ test_parmsz_unknown (void *obj, void *unknown, size_t sz, int cond) return __builtin_dynamic_object_size (cond ? obj : unknown, 0); } +struct S; +size_t +__attribute__ ((access (__read_write__, 1, 2))) +__attribute__ ((noinline)) +test_parmsz_extern (struct S *obj, size_t sz) +{ + return __builtin_dynamic_object_size (obj, 0); +} + +/* Implicitly constructed access attributes not supported yet. */ +size_t +__attribute__ ((noinline)) +test_parmsz_internal (size_t sz, double obj[][sz]) +{ + return __builtin_dynamic_object_size (obj, 0); +} + +size_t +__attribute__ ((access (__read_write__, 2, 1))) +__attribute__ ((noinline)) +test_parmsz_internal2 (size_t sz, double obj[][sz]) +{ + return __builtin_dynamic_object_size (obj, 0); +} + +size_t +__attribute__ ((noinline)) +test_parmsz_internal3 (size_t sz1, size_t sz2, double obj[sz1][sz2]) +{ + return __builtin_dynamic_object_size (obj, 0); +} + /* Loops. */ size_t @@ -532,9 +580,22 @@ main (int argc, char **argv) if (test_parmsz_simple (argv[0], __builtin_strlen (argv[0]) + 1) != __builtin_strlen (argv[0]) + 1) FAIL (); + if (test_parmsz_simple2 (__builtin_strlen (argv[0]) + 1, argv[0]) + != __builtin_strlen (argv[0]) + 1) + FAIL (); + /* Only explicitly added access attributes are supported for now. */ + if (test_parmsz_simple3 (__builtin_strlen (argv[0]) + 1, argv[0]) != -1) + FAIL (); int arr[42]; if (test_parmsz_scaled (arr, 42) != sizeof (arr)) FAIL (); + if (test_parmsz_scaled (arr, 40) != 40 * sizeof (int)) + FAIL (); + /* __bdos cannot see the actual size of ARR, so it will return what it was + passed. Fortunately though the overflow warnings see this caller side and + warns of the problematic size. */ + if (test_parmsz_scaled (arr, 44) != 44 * sizeof (int)) /* { dg-warning "-Wstringop-overflow=" } */ + FAIL (); if (test_parmsz_unknown (argv[0], argv[0], __builtin_strlen (argv[0]) + 1, 0) != -1) if (test_parmsz (argv[0], __builtin_strlen (argv[0]) + 1, -1) != 0) @@ -550,6 +611,16 @@ main (int argc, char **argv) FAIL (); if (test_parmsz_scaled_off (arr, 42, 2) != 40 * sizeof (int)) FAIL (); + struct S *s; + if (test_parmsz_extern (s, 42) != -1) + FAIL (); + double obj[4][4]; + if (test_parmsz_internal (4, obj) != -1) + FAIL (); + if (test_parmsz_internal2 (4, obj) != -1) + FAIL (); + if (test_parmsz_internal3 (4, 4, obj) != -1) + FAIL (); if (test_loop (arr, 42, 0, 32, 1) != 10 * sizeof (int)) FAIL (); if (test_loop (arr, 42, 32, -1, -1) != 0) diff --git a/gcc/tree-object-size.cc b/gcc/tree-object-size.cc index b0b50774936..fc062b94d76 100644 --- a/gcc/tree-object-size.cc +++ b/gcc/tree-object-size.cc @@ -1477,14 +1477,19 @@ parm_object_size (struct object_size_info *osi, tree var) tree typesize = TYPE_SIZE_UNIT (TREE_TYPE (TREE_TYPE (parm))); tree sz = NULL_TREE; - if (access && access->sizarg != UINT_MAX) + /* If we have an explicit access attribute with a usable size argument... */ + if (access && access->sizarg != UINT_MAX && !access->internal_p + /* ... and either PARM is void * or has a type that is complete and has a + constant size... */ + && ((typesize && poly_int_tree_p (typesize)) + || (!typesize && VOID_TYPE_P (TREE_TYPE (TREE_TYPE (parm)))))) { tree fnargs = DECL_ARGUMENTS (fndecl); tree arg = NULL_TREE; unsigned argpos = 0; - /* Walk through the parameters to pick the size parameter and safely - scale it by the type size. */ + /* ... then walk through the parameters to pick the size parameter and + safely scale it by the type size if needed. */ for (arg = fnargs; arg; arg = TREE_CHAIN (arg), ++argpos) if (argpos == access->sizarg && INTEGRAL_TYPE_P (TREE_TYPE (arg))) {
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