Improve optimization of ASan checks.
2014-12-03 Yury Gribov <y.gribov@samsung.com> gcc/ * sanopt.c (maybe_get_single_definition): New function. (maybe_get_dominating_check): Ditto. (can_remove_asan_check): Ditto. (struct tree_map_traits): New struct. (struct sanopt_ctx): Use custom traits for asan_check_map. (maybe_optimize_ubsan_null_ifn): Move code to maybe_get_dominating_check. (maybe_optimize_asan_check_ifn): Move code and take non-SSA expressions into account when optimizing. (sanopt_optimize_walker): Optimize ASan checks even when recovering. From-SVN: r218304
This commit is contained in:
Yury Gribov
Yury Gribov
parent
45392c7650
commit
e28f2090db
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@ -1,3 +1,17 @@
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2014-12-03 Yury Gribov <y.gribov@samsung.com>
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* sanopt.c (maybe_get_single_definition): New function.
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(maybe_get_dominating_check): Ditto.
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(can_remove_asan_check): Ditto.
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(struct tree_map_traits): New struct.
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(struct sanopt_ctx): Use custom traits for asan_check_map.
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(maybe_optimize_ubsan_null_ifn): Move code to
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maybe_get_dominating_check.
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(maybe_optimize_asan_check_ifn): Move code and take non-SSA expressions
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into account when optimizing.
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(sanopt_optimize_walker): Optimize ASan checks even when
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recovering.
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2014-12-03 Ilya Enkovich <ilya.enkovich@intel.com>
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* config/i386/constraints.md (Yr): New.
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233
gcc/sanopt.c
233
gcc/sanopt.c
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@ -84,6 +84,35 @@ struct sanopt_info
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bool visited_p;
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};
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/* If T has a single definition of form T = T2, return T2. */
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static tree
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maybe_get_single_definition (tree t)
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{
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if (TREE_CODE (t) == SSA_NAME)
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{
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gimple g = SSA_NAME_DEF_STMT (t);
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if (gimple_assign_single_p (g))
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return gimple_assign_rhs1 (g);
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}
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return NULL_TREE;
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}
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/* Traits class for tree hash maps below. */
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struct tree_map_traits : default_hashmap_traits
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{
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static inline hashval_t hash (const_tree ref)
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{
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return iterative_hash_expr (ref, 0);
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}
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static inline bool equal_keys (const_tree ref1, const_tree ref2)
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{
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return operand_equal_p (ref1, ref2, 0);
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}
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};
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/* This is used to carry various hash maps and variables used
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in sanopt_optimize_walker. */
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@ -95,7 +124,7 @@ struct sanopt_ctx
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/* This map maps a pointer (the second argument of ASAN_CHECK) to
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a vector of ASAN_CHECK call statements that check the access. */
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hash_map<tree, auto_vec<gimple> > asan_check_map;
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hash_map<tree, auto_vec<gimple>, tree_map_traits> asan_check_map;
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/* Number of IFN_ASAN_CHECK statements. */
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int asan_num_accesses;
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@ -197,6 +226,24 @@ imm_dom_path_with_freeing_call (basic_block bb, basic_block dom)
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return false;
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}
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/* Get the first dominating check from the list of stored checks.
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Non-dominating checks are silently dropped. */
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static gimple
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maybe_get_dominating_check (auto_vec<gimple> &v)
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{
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for (; !v.is_empty (); v.pop ())
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{
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gimple g = v.last ();
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sanopt_info *si = (sanopt_info *) gimple_bb (g)->aux;
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if (!si->visited_p)
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/* At this point we shouldn't have any statements
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that aren't dominating the current BB. */
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return g;
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}
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return NULL;
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}
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/* Optimize away redundant UBSAN_NULL calls. */
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static bool
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@ -209,7 +256,8 @@ maybe_optimize_ubsan_null_ifn (struct sanopt_ctx *ctx, gimple stmt)
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bool remove = false;
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auto_vec<gimple> &v = ctx->null_check_map.get_or_insert (ptr);
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if (v.is_empty ())
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gimple g = maybe_get_dominating_check (v);
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if (!g)
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{
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/* For this PTR we don't have any UBSAN_NULL stmts recorded, so there's
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nothing to optimize yet. */
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@ -220,90 +268,42 @@ maybe_optimize_ubsan_null_ifn (struct sanopt_ctx *ctx, gimple stmt)
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/* We already have recorded a UBSAN_NULL check for this pointer. Perhaps we
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can drop this one. But only if this check doesn't specify stricter
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alignment. */
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while (!v.is_empty ())
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{
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gimple g = v.last ();
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/* Remove statements for BBs that have been already processed. */
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sanopt_info *si = (sanopt_info *) gimple_bb (g)->aux;
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if (si->visited_p)
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{
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v.pop ();
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continue;
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}
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/* At this point we shouldn't have any statements that aren't dominating
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the current BB. */
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tree align = gimple_call_arg (g, 2);
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int kind = tree_to_shwi (gimple_call_arg (g, 1));
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/* If this is a NULL pointer check where we had segv anyway, we can
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remove it. */
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if (integer_zerop (align)
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&& (kind == UBSAN_LOAD_OF
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|| kind == UBSAN_STORE_OF
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|| kind == UBSAN_MEMBER_ACCESS))
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remove = true;
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/* Otherwise remove the check in non-recovering mode, or if the
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stmts have same location. */
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else if (integer_zerop (align))
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remove = (flag_sanitize_recover & SANITIZE_NULL) == 0
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|| flag_sanitize_undefined_trap_on_error
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|| gimple_location (g) == gimple_location (stmt);
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else if (tree_int_cst_le (cur_align, align))
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remove = (flag_sanitize_recover & SANITIZE_ALIGNMENT) == 0
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|| flag_sanitize_undefined_trap_on_error
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|| gimple_location (g) == gimple_location (stmt);
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if (!remove && gimple_bb (g) == gimple_bb (stmt)
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&& tree_int_cst_compare (cur_align, align) == 0)
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v.pop ();
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break;
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}
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tree align = gimple_call_arg (g, 2);
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int kind = tree_to_shwi (gimple_call_arg (g, 1));
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/* If this is a NULL pointer check where we had segv anyway, we can
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remove it. */
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if (integer_zerop (align)
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&& (kind == UBSAN_LOAD_OF
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|| kind == UBSAN_STORE_OF
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|| kind == UBSAN_MEMBER_ACCESS))
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remove = true;
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/* Otherwise remove the check in non-recovering mode, or if the
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stmts have same location. */
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else if (integer_zerop (align))
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remove = (flag_sanitize_recover & SANITIZE_NULL) == 0
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|| flag_sanitize_undefined_trap_on_error
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|| gimple_location (g) == gimple_location (stmt);
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else if (tree_int_cst_le (cur_align, align))
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remove = (flag_sanitize_recover & SANITIZE_ALIGNMENT) == 0
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|| flag_sanitize_undefined_trap_on_error
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|| gimple_location (g) == gimple_location (stmt);
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if (!remove && gimple_bb (g) == gimple_bb (stmt)
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&& tree_int_cst_compare (cur_align, align) == 0)
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v.pop ();
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if (!remove)
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v.safe_push (stmt);
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return remove;
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}
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/* Optimize away redundant ASAN_CHECK calls. */
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/* Returns TRUE if ASan check of length LEN in block BB can be removed
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if preceded by checks in V. */
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static bool
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maybe_optimize_asan_check_ifn (struct sanopt_ctx *ctx, gimple stmt)
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can_remove_asan_check (auto_vec<gimple> &v, tree len, basic_block bb)
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{
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gcc_assert (gimple_call_num_args (stmt) == 4);
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tree ptr = gimple_call_arg (stmt, 1);
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tree len = gimple_call_arg (stmt, 2);
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basic_block bb = gimple_bb (stmt);
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sanopt_info *info = (sanopt_info *) bb->aux;
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if (TREE_CODE (len) != INTEGER_CST)
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return false;
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if (integer_zerop (len))
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return false;
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gimple_set_uid (stmt, info->freeing_call_events);
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auto_vec<gimple> &v = ctx->asan_check_map.get_or_insert (ptr);
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if (v.is_empty ())
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{
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/* For this PTR we don't have any ASAN_CHECK stmts recorded, so there's
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nothing to optimize yet. */
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v.safe_push (stmt);
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return false;
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}
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/* We already have recorded a ASAN_CHECK check for this pointer. Perhaps
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we can drop this one. But only if this check doesn't specify larger
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size. */
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while (!v.is_empty ())
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{
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gimple g = v.last ();
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/* Remove statements for BBs that have been already processed. */
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sanopt_info *si = (sanopt_info *) gimple_bb (g)->aux;
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if (si->visited_p)
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v.pop ();
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else
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break;
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}
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unsigned int i;
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gimple g;
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gimple to_pop = NULL;
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@ -323,17 +323,9 @@ maybe_optimize_asan_check_ifn (struct sanopt_ctx *ctx, gimple stmt)
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continue;
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}
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if (TREE_CODE (len) != INTEGER_CST)
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{
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/* If there is some stmts not followed by freeing call event
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for ptr already in the current bb, no need to insert anything.
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Non-constant len is treated just as length 1. */
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if (gbb == bb)
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return false;
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break;
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}
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tree glen = gimple_call_arg (g, 2);
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gcc_assert (TREE_CODE (glen) == INTEGER_CST);
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/* If we've checked only smaller length than we want to check now,
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we can't remove the current stmt. If g is in the same basic block,
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we want to remove it though, as the current stmt is better. */
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@ -383,8 +375,70 @@ maybe_optimize_asan_check_ifn (struct sanopt_ctx *ctx, gimple stmt)
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v.truncate (j);
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}
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return remove;
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}
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/* Optimize away redundant ASAN_CHECK calls. */
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static bool
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maybe_optimize_asan_check_ifn (struct sanopt_ctx *ctx, gimple stmt)
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{
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gcc_assert (gimple_call_num_args (stmt) == 4);
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tree ptr = gimple_call_arg (stmt, 1);
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tree len = gimple_call_arg (stmt, 2);
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basic_block bb = gimple_bb (stmt);
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sanopt_info *info = (sanopt_info *) bb->aux;
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if (TREE_CODE (len) != INTEGER_CST)
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return false;
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if (integer_zerop (len))
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return false;
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gimple_set_uid (stmt, info->freeing_call_events);
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auto_vec<gimple> *ptr_checks = &ctx->asan_check_map.get_or_insert (ptr);
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tree base_addr = maybe_get_single_definition (ptr);
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auto_vec<gimple> *base_checks = NULL;
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if (base_addr)
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{
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base_checks = &ctx->asan_check_map.get_or_insert (base_addr);
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/* Original pointer might have been invalidated. */
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ptr_checks = ctx->asan_check_map.get (ptr);
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}
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gimple g = maybe_get_dominating_check (*ptr_checks);
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if (!g && base_checks)
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/* Try with base address as well. */
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g = maybe_get_dominating_check (*base_checks);
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if (!g)
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{
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/* For this PTR we don't have any ASAN_CHECK stmts recorded, so there's
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nothing to optimize yet. */
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ptr_checks->safe_push (stmt);
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if (base_checks)
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base_checks->safe_push (stmt);
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return false;
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}
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bool remove = false;
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if (ptr_checks)
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remove = can_remove_asan_check (*ptr_checks, len, bb);
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if (!remove && base_checks)
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/* Try with base address as well. */
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remove = can_remove_asan_check (*base_checks, len, bb);
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if (!remove)
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v.safe_push (stmt);
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{
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ptr_checks->safe_push (stmt);
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if (base_checks)
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base_checks->safe_push (stmt);
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}
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return remove;
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}
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@ -404,10 +458,7 @@ sanopt_optimize_walker (basic_block bb, struct sanopt_ctx *ctx)
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basic_block son;
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gimple_stmt_iterator gsi;
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sanopt_info *info = (sanopt_info *) bb->aux;
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bool asan_check_optimize
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= (flag_sanitize & SANITIZE_ADDRESS)
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&& ((flag_sanitize & flag_sanitize_recover
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& SANITIZE_KERNEL_ADDRESS) == 0);
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bool asan_check_optimize = (flag_sanitize & SANITIZE_ADDRESS) != 0;
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for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi);)
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{
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