Handle hints provided by __attribute__ ((access (...))) to compute dynamic sizes for objects.
gcc/ChangeLog: * tree-object-size.c: Include tree-dfa.h. (parm_object_size): New function. (collect_object_sizes_for): Call it. gcc/testsuite/ChangeLog: * gcc.dg/builtin-dynamic-object-size-0.c (test_parmsz_simple, test_parmsz_scaled, test_parmsz_unknown): New functions. (main): Call them. Add new arguments argc and argv. Signed-off-by: Siddhesh Poyarekar <siddh...@gotplt.org> --- .../gcc.dg/builtin-dynamic-object-size-0.c | 35 +++++++++++- gcc/tree-object-size.c | 54 ++++++++++++++++++- 2 files changed, 87 insertions(+), 2 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 b1013e19fd0..c89e2268943 100644 --- a/gcc/testsuite/gcc.dg/builtin-dynamic-object-size-0.c +++ b/gcc/testsuite/gcc.dg/builtin-dynamic-object-size-0.c @@ -34,6 +34,30 @@ test_deploop (size_t sz, size_t cond) return __builtin_dynamic_object_size (bin, 0); } +size_t +__attribute__ ((access (__read_write__, 1, 2))) +__attribute__ ((noinline)) +test_parmsz_simple (void *obj, size_t sz) +{ + return __builtin_dynamic_object_size (obj, 0); +} + +size_t +__attribute__ ((access (__read_write__, 1, 2))) +__attribute__ ((noinline)) +test_parmsz_scaled (int *obj, size_t sz) +{ + return __builtin_dynamic_object_size (obj, 0); +} + +size_t +__attribute__ ((access (__read_write__, 1, 3))) +__attribute__ ((noinline)) +test_parmsz_unknown (void *obj, void *unknown, size_t sz, int cond) +{ + return __builtin_dynamic_object_size (cond ? obj : unknown, 0); +} + unsigned nfails = 0; #define FAIL() ({ \ @@ -42,7 +66,7 @@ unsigned nfails = 0; }) int -main () +main (int argc, char **argv) { if (test_builtin_malloc_condphi (1) != 32) FAIL (); @@ -50,6 +74,15 @@ main () FAIL (); if (test_deploop (128, 129) != 32) FAIL (); + if (test_parmsz_simple (argv[0], __builtin_strlen (argv[0]) + 1) + != __builtin_strlen (argv[0]) + 1) + FAIL (); + int arr[42]; + if (test_parmsz_scaled (arr, 42) != sizeof (arr)) + FAIL (); + if (test_parmsz_unknown (argv[0], argv[0], __builtin_strlen (argv[0]) + 1, 0) + != -1) + FAIL (); if (nfails > 0) __builtin_abort (); diff --git a/gcc/tree-object-size.c b/gcc/tree-object-size.c index 775792b4419..47e1c27bfd3 100644 --- a/gcc/tree-object-size.c +++ b/gcc/tree-object-size.c @@ -32,6 +32,7 @@ along with GCC; see the file COPYING3. If not see #include "gimple-fold.h" #include "gimple-iterator.h" #include "tree-cfg.h" +#include "tree-dfa.h" #include "stringpool.h" #include "attribs.h" #include "builtins.h" @@ -1443,6 +1444,57 @@ cond_expr_object_size (struct object_size_info *osi, tree var, gimple *stmt) return reexamine; } +/* Find size of an object passed as a parameter to the function. */ + +static void +parm_object_size (struct object_size_info *osi, tree var) +{ + int object_size_type = osi->object_size_type; + tree parm = SSA_NAME_VAR (var); + + if (!(object_size_type & OST_DYNAMIC) || !POINTER_TYPE_P (TREE_TYPE (parm))) + { + expr_object_size (osi, var, parm); + return; + } + + /* Look for access attribute. */ + rdwr_map rdwr_idx; + + tree fndecl = cfun->decl; + const attr_access *access = get_parm_access (rdwr_idx, parm, fndecl); + tree typesize = TYPE_SIZE_UNIT (TREE_TYPE (TREE_TYPE (parm))); + tree sz = NULL_TREE; + + if (access && access->sizarg != UINT_MAX) + { + 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. */ + for (arg = fnargs; arg; arg = TREE_CHAIN (arg), ++argpos) + { + if (argpos == access->sizarg && INTEGRAL_TYPE_P (TREE_TYPE (arg))) + { + sz = get_or_create_ssa_default_def (cfun, arg); + if (sz != NULL_TREE) + { + sz = fold_convert (sizetype, sz); + if (typesize) + sz = size_binop (MULT_EXPR, sz, typesize); + } + break; + } + } + } + if (!sz) + sz = size_unknown (object_size_type); + + object_sizes_set (osi, SSA_NAME_VERSION (var), sz, sz); +} + /* Compute an object size expression for VAR, which is the result of a PHI node. */ @@ -1620,7 +1672,7 @@ collect_object_sizes_for (struct object_size_info *osi, tree var) case GIMPLE_NOP: if (SSA_NAME_VAR (var) && TREE_CODE (SSA_NAME_VAR (var)) == PARM_DECL) - expr_object_size (osi, var, SSA_NAME_VAR (var)); + parm_object_size (osi, var); else /* Uninitialized SSA names point nowhere. */ unknown_object_size (osi, var); -- 2.33.1