again for plain uninitialized variables, since optimization may have
changed conditionally uninitialized to unconditionally uninitialized. */
-/* Emit a warning for T, an SSA_NAME, being uninitialized. The exact
+/* Emit a warning for EXPR based on variable VAR at the point in the
+ program T, an SSA_NAME, is used being uninitialized. The exact
warning text is in MSGID and LOCUS may contain a location or be null.
WC is the warning code. */
void
-warn_uninit (enum opt_code wc, tree t, const char *gmsgid, void *data)
+warn_uninit (enum opt_code wc, tree t,
+ tree expr, tree var, const char *gmsgid, void *data)
{
- tree var = SSA_NAME_VAR (t);
gimple context = (gimple) data;
location_t location;
expanded_location xloc, floc;
/* TREE_NO_WARNING either means we already warned, or the front end
wishes to suppress the warning. */
- if (TREE_NO_WARNING (var))
- return;
-
- /* Do not warn if it can be initialized outside this module. */
- if (is_global_var (var))
+ if ((context
+ && (gimple_no_warning_p (context)
+ || (gimple_assign_single_p (context)
+ && TREE_NO_WARNING (gimple_assign_rhs1 (context)))))
+ || TREE_NO_WARNING (expr))
return;
location = (context != NULL && gimple_has_location (context))
: DECL_SOURCE_LOCATION (var);
xloc = expand_location (location);
floc = expand_location (DECL_SOURCE_LOCATION (cfun->decl));
- if (warning_at (location, wc, gmsgid, var))
+ if (warning_at (location, wc, gmsgid, expr))
{
- TREE_NO_WARNING (var) = 1;
+ TREE_NO_WARNING (expr) = 1;
if (location == DECL_SOURCE_LOCATION (var))
return;
}
}
-struct walk_data {
- gimple stmt;
- bool always_executed;
- bool warn_possibly_uninitialized;
-};
-
-/* Called via walk_tree, look for SSA_NAMEs that have empty definitions
- and warn about them. */
-
-static tree
-warn_uninitialized_var (tree *tp, int *walk_subtrees, void *data_)
-{
- struct walk_stmt_info *wi = (struct walk_stmt_info *) data_;
- struct walk_data *data = (struct walk_data *) wi->info;
- tree t = *tp;
-
- /* We do not care about LHS. */
- if (wi->is_lhs)
- {
- /* Except for operands of dereferences. */
- if (!INDIRECT_REF_P (t)
- && TREE_CODE (t) != MEM_REF)
- return NULL_TREE;
- t = TREE_OPERAND (t, 0);
- }
-
- switch (TREE_CODE (t))
- {
- case ADDR_EXPR:
- /* Taking the address of an uninitialized variable does not
- count as using it. */
- *walk_subtrees = 0;
- break;
-
- case VAR_DECL:
- {
- /* A VAR_DECL in the RHS of a gimple statement may mean that
- this variable is loaded from memory. */
- use_operand_p vuse;
- tree op;
-
- /* If there is not gimple stmt,
- or alias information has not been computed,
- then we cannot check VUSE ops. */
- if (data->stmt == NULL)
- return NULL_TREE;
-
- /* If the load happens as part of a call do not warn about it. */
- if (is_gimple_call (data->stmt))
- return NULL_TREE;
-
- vuse = gimple_vuse_op (data->stmt);
- if (vuse == NULL_USE_OPERAND_P)
- return NULL_TREE;
-
- op = USE_FROM_PTR (vuse);
- if (t != SSA_NAME_VAR (op)
- || !SSA_NAME_IS_DEFAULT_DEF (op))
- return NULL_TREE;
- /* If this is a VUSE of t and it is the default definition,
- then warn about op. */
- t = op;
- /* Fall through into SSA_NAME. */
- }
-
- case SSA_NAME:
- /* We only do data flow with SSA_NAMEs, so that's all we
- can warn about. */
- if (data->always_executed)
- warn_uninit (OPT_Wuninitialized,
- t, "%qD is used uninitialized in this function",
- data->stmt);
- else if (data->warn_possibly_uninitialized)
- warn_uninit (OPT_Wuninitialized,
- t, "%qD may be used uninitialized in this function",
- data->stmt);
- *walk_subtrees = 0;
- break;
-
- case REALPART_EXPR:
- case IMAGPART_EXPR:
- /* The total store transformation performed during gimplification
- creates uninitialized variable uses. If all is well, these will
- be optimized away, so don't warn now. */
- if (TREE_CODE (TREE_OPERAND (t, 0)) == SSA_NAME)
- *walk_subtrees = 0;
- break;
-
- default:
- if (IS_TYPE_OR_DECL_P (t))
- *walk_subtrees = 0;
- break;
- }
-
- return NULL_TREE;
-}
-
unsigned int
warn_uninitialized_vars (bool warn_possibly_uninitialized)
{
gimple_stmt_iterator gsi;
basic_block bb;
- struct walk_data data;
-
- data.warn_possibly_uninitialized = warn_possibly_uninitialized;
-
FOR_EACH_BB (bb)
{
- data.always_executed = dominated_by_p (CDI_POST_DOMINATORS,
+ bool always_executed = dominated_by_p (CDI_POST_DOMINATORS,
single_succ (ENTRY_BLOCK_PTR), bb);
for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
{
- struct walk_stmt_info wi;
- data.stmt = gsi_stmt (gsi);
- if (is_gimple_debug (data.stmt))
+ gimple stmt = gsi_stmt (gsi);
+ use_operand_p use_p;
+ ssa_op_iter op_iter;
+ tree use;
+
+ if (is_gimple_debug (stmt))
continue;
- memset (&wi, 0, sizeof (wi));
- wi.info = &data;
- walk_gimple_op (gsi_stmt (gsi), warn_uninitialized_var, &wi);
+
+ /* We only do data flow with SSA_NAMEs, so that's all we
+ can warn about. */
+ FOR_EACH_SSA_USE_OPERAND (use_p, stmt, op_iter, SSA_OP_USE)
+ {
+ use = USE_FROM_PTR (use_p);
+ if (always_executed)
+ warn_uninit (OPT_Wuninitialized, use,
+ SSA_NAME_VAR (use), SSA_NAME_VAR (use),
+ "%qD is used uninitialized in this function",
+ stmt);
+ else if (warn_possibly_uninitialized)
+ warn_uninit (OPT_Wuninitialized, use,
+ SSA_NAME_VAR (use), SSA_NAME_VAR (use),
+ "%qD may be used uninitialized in this function",
+ stmt);
+ }
+
+ /* For memory the only cheap thing we can do is see if we
+ have a use of the default def of the virtual operand.
+ ??? Note that at -O0 we do not have virtual operands.
+ ??? Not so cheap would be to use the alias oracle via
+ walk_aliased_vdefs, if we don't find any aliasing vdef
+ warn as is-used-uninitialized, if we don't find an aliasing
+ vdef that kills our use (stmt_kills_ref_p), warn as
+ may-be-used-uninitialized. But this walk is quadratic and
+ so must be limited which means we would miss warning
+ opportunities. */
+ use = gimple_vuse (stmt);
+ if (use
+ && gimple_assign_single_p (stmt)
+ && !gimple_vdef (stmt)
+ && SSA_NAME_IS_DEFAULT_DEF (use))
+ {
+ tree rhs = gimple_assign_rhs1 (stmt);
+ tree base = get_base_address (rhs);
+
+ /* Do not warn if it can be initialized outside this function. */
+ if (TREE_CODE (base) != VAR_DECL
+ || DECL_HARD_REGISTER (base)
+ || is_global_var (base))
+ continue;
+
+ if (always_executed)
+ warn_uninit (OPT_Wuninitialized, use, gimple_assign_rhs1 (stmt),
+ base,
+ "%qE is used uninitialized in this function",
+ stmt);
+ else if (warn_possibly_uninitialized)
+ warn_uninit (OPT_Wuninitialized, use, gimple_assign_rhs1 (stmt),
+ base,
+ "%qE may be used uninitialized in this function",
+ stmt);
+ }
}
}
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