For instance, on an x86, you could compile a function with
@code{target_clones("sse4.1,avx")}. GCC creates two function clones,
one compiled with @option{-msse4.1} and another with @option{-mavx}.
-It also creates a resolver function (see the @code{ifunc} attribute
-above) that dynamically selects a clone suitable for current
-architecture.
On a PowerPC, you can compile a function with
@code{target_clones("cpu=power9,default")}. GCC will create two
function clones, one compiled with @option{-mcpu=power9} and another
-with the default options. It also creates a resolver function (see
+with the default options.
+
+It also creates a resolver function (see
the @code{ifunc} attribute above) that dynamically selects a clone
-suitable for current architecture.
+suitable for current architecture. The resolver is created only if there
+is a usage of a function with @code{target_clones} attribute.
@item unused
@cindex @code{unused} function attribute
#include "gimple-ssa.h"
#include "tree-phinodes.h"
#include "ssa-iterators.h"
+#include "gimplify.h"
+#include "gimple-iterator.h"
+#include "gimple-walk.h"
+#include "cfghooks.h"
+#include "tree-dfa.h"
+#include "tree-ssa.h"
/* This is used to carry information about basic blocks. It is
attached to the AUX field of the standard CFG block. */
}
}
+/* Rewrite all usages of tree OP which is a PARM_DECL with a VAR_DECL
+ that is it's DECL_VALUE_EXPR. */
+
+static tree
+rewrite_usage_of_param (tree *op, int *walk_subtrees, void *)
+{
+ if (TREE_CODE (*op) == PARM_DECL && DECL_HAS_VALUE_EXPR_P (*op))
+ {
+ *op = DECL_VALUE_EXPR (*op);
+ *walk_subtrees = 0;
+ }
+
+ return NULL;
+}
+
+/* For a given function FUN, rewrite all addressable parameters so that
+ a new automatic variable is introduced. Right after function entry
+ a parameter is assigned to the variable. */
+
+static void
+sanitize_rewrite_addressable_params (function *fun)
+{
+ gimple *g;
+ gimple_seq stmts = NULL;
+ bool has_any_addressable_param = false;
+ auto_vec<tree> clear_value_expr_list;
+
+ for (tree arg = DECL_ARGUMENTS (current_function_decl);
+ arg; arg = DECL_CHAIN (arg))
+ {
+ if (TREE_ADDRESSABLE (arg) && !TREE_ADDRESSABLE (TREE_TYPE (arg)))
+ {
+ TREE_ADDRESSABLE (arg) = 0;
+ /* The parameter is no longer addressable. */
+ tree type = TREE_TYPE (arg);
+ has_any_addressable_param = true;
+
+ /* Create a new automatic variable. */
+ tree var = build_decl (DECL_SOURCE_LOCATION (arg),
+ VAR_DECL, DECL_NAME (arg), type);
+ TREE_ADDRESSABLE (var) = 1;
+ DECL_ARTIFICIAL (var) = 1;
+
+ gimple_add_tmp_var (var);
+
+ if (dump_file)
+ fprintf (dump_file,
+ "Rewriting parameter whose address is taken: %s\n",
+ IDENTIFIER_POINTER (DECL_NAME (arg)));
+
+ gcc_assert (!DECL_HAS_VALUE_EXPR_P (arg));
+ DECL_HAS_VALUE_EXPR_P (arg) = 1;
+ SET_DECL_VALUE_EXPR (arg, var);
+
+ SET_DECL_PT_UID (var, DECL_PT_UID (arg));
+
+ /* Assign value of parameter to newly created variable. */
+ if ((TREE_CODE (type) == COMPLEX_TYPE
+ || TREE_CODE (type) == VECTOR_TYPE))
+ {
+ /* We need to create a SSA name that will be used for the
+ assignment. */
+ DECL_GIMPLE_REG_P (arg) = 1;
+ tree tmp = get_or_create_ssa_default_def (cfun, arg);
+ g = gimple_build_assign (var, tmp);
+ gimple_set_location (g, DECL_SOURCE_LOCATION (arg));
+ gimple_seq_add_stmt (&stmts, g);
+ }
+ else
+ {
+ g = gimple_build_assign (var, arg);
+ gimple_set_location (g, DECL_SOURCE_LOCATION (arg));
+ gimple_seq_add_stmt (&stmts, g);
+ }
+
+ if (target_for_debug_bind (arg))
+ {
+ g = gimple_build_debug_bind (arg, var, NULL);
+ gimple_seq_add_stmt (&stmts, g);
+ clear_value_expr_list.safe_push (arg);
+ }
+ }
+ }
+
+ if (!has_any_addressable_param)
+ return;
+
+ /* Replace all usages of PARM_DECLs with the newly
+ created variable VAR. */
+ basic_block bb;
+ FOR_EACH_BB_FN (bb, fun)
+ {
+ gimple_stmt_iterator gsi;
+ for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+ {
+ gimple *stmt = gsi_stmt (gsi);
+ gimple_stmt_iterator it = gsi_for_stmt (stmt);
+ walk_gimple_stmt (&it, NULL, rewrite_usage_of_param, NULL);
+ }
+ for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+ {
+ gphi *phi = dyn_cast<gphi *> (gsi_stmt (gsi));
+ for (unsigned i = 0; i < gimple_phi_num_args (phi); ++i)
+ {
+ hash_set<tree> visited_nodes;
+ walk_tree (gimple_phi_arg_def_ptr (phi, i),
+ rewrite_usage_of_param, NULL, &visited_nodes);
+ }
+ }
+ }
+
+ /* Unset value expr for parameters for which we created debug bind
+ expressions. */
+ unsigned i;
+ tree arg;
+ FOR_EACH_VEC_ELT (clear_value_expr_list, i, arg)
+ {
+ DECL_HAS_VALUE_EXPR_P (arg) = 0;
+ SET_DECL_VALUE_EXPR (arg, NULL_TREE);
+ }
+
+ /* Insert default assignments at the beginning of a function. */
+ basic_block entry_bb = ENTRY_BLOCK_PTR_FOR_FN (fun);
+ entry_bb = split_edge (single_succ_edge (entry_bb));
+
+ gimple_stmt_iterator gsi = gsi_start_bb (entry_bb);
+ gsi_insert_seq_before (&gsi, stmts, GSI_NEW_STMT);
+}
+
unsigned int
pass_sanopt::execute (function *fun)
{
sanitize_asan_mark_poison ();
}
+ if (asan_sanitize_stack_p ())
+ sanitize_rewrite_addressable_params (fun);
+
bool use_calls = ASAN_INSTRUMENTATION_WITH_CALL_THRESHOLD < INT_MAX
&& asan_num_accesses >= ASAN_INSTRUMENTATION_WITH_CALL_THRESHOLD;
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