The following implements additional checking around
SSA immediate use iteration. Specifically this prevents
- any nesting of FOR_EACH_IMM_USE_STMT inside another iteration
via FOR_EACH_IMM_USE_STMT or FOR_EACH_IMM_USE_FAST when iterating
on the same SSA name
- modification (for now unlinking of immediate uses) of a SSA
immediate use list when a fast iteration of the immediate uses
of the SSA name is active
- modification (for now unlinking of immediate uses) of the immediate
use list outside of the block of uses for the currently active stmt
of an ongoing FOR_EACH_IMM_USE_STMT of the SSA name
To implement this additional bookkeeping members are put into the
SSA name structure when ENABLE_GIMPLE_CHECKING is active. I have
kept the existing consistency checking of the fast iterator.
* ssa-iterators.h (imm_use_iterator::name): Add.
(delink_imm_use): When in a FOR_EACH_IMM_USE_STMT iteration
enforce we only remove uses from the current stmt.
(end_imm_use_stmt_traverse): Reset current stmt.
(first_imm_use_stmt): Assert no FOR_EACH_IMM_USE_STMT on
var is in progress. Set the current stmt.
(next_imm_use_stmt): Set the current stmt.
(auto_end_imm_use_fast_traverse): New, lower iteration
depth upon destruction.
(first_readonly_imm_use): Bump the iteration depth.
* tree-ssanames.cc (make_ssa_name_fn): Initialize
immediate use verifier bookkeeping members.
---
gcc/ssa-iterators.h | 58 +++++++++++++++++++++++++++++++++++++++++++-
gcc/tree-core.h | 4 +++
gcc/tree-ssanames.cc | 4 +++
3 files changed, 65 insertions(+), 1 deletion(-)
diff --git a/gcc/ssa-iterators.h b/gcc/ssa-iterators.h
index 8fcc9b8a55f..24cf6bfd63b 100644
--- a/gcc/ssa-iterators.h
+++ b/gcc/ssa-iterators.h
@@ -59,16 +59,40 @@ struct imm_use_iterator
/* This is the next ssa_name to visit. IMM_USE may get removed before
the next one is traversed to, so it must be cached early. */
ssa_use_operand_t *next_imm_name;
+ /* This is the SSA name iterated over. */
+ tree name;
};
/* Use this iterator when simply looking at stmts. Adding, deleting or
modifying stmts will cause this iterator to malfunction. */
+#if ! defined ENABLE_GIMPLE_CHECKING
#define FOR_EACH_IMM_USE_FAST(DEST, ITER, SSAVAR) \
for ((DEST) = first_readonly_imm_use (&(ITER), (SSAVAR)); \
!end_readonly_imm_use_p (&(ITER)); \
(void) ((DEST) = next_readonly_imm_use (&(ITER))))
+#else
+
+/* arrange to automatically call, upon descruction, with a given pointer
+ to imm_use_iterator. */
+struct auto_end_imm_use_fast_traverse
+{
+ imm_use_iterator *imm;
+ auto_end_imm_use_fast_traverse (imm_use_iterator *imm)
+ : imm (imm) {}
+ ~auto_end_imm_use_fast_traverse ()
+ { imm->name->ssa_name.fast_iteration_depth--; }
+};
+
+#define FOR_EACH_IMM_USE_FAST(DEST, ITER, SSAVAR) \
+ for (struct auto_end_imm_use_fast_traverse \
+ auto_end_imm_use_fast_traverse \
+ ((((DEST) = first_readonly_imm_use (&(ITER), (SSAVAR))), \
+ &(ITER))); \
+ !end_readonly_imm_use_p (&(ITER)); \
+ (void) ((DEST) = next_readonly_imm_use (&(ITER))))
+#endif
/* Forward declare for use in the class below. */
inline void end_imm_use_stmt_traverse (imm_use_iterator *);
@@ -251,6 +275,20 @@ delink_imm_use (ssa_use_operand_t *linknode)
if (linknode->prev == NULL)
return;
+#if defined ENABLE_GIMPLE_CHECKING
+ if (linknode->loc.stmt
+ /* update_stmt on constant/removed uses. */
+ && USE_FROM_PTR (linknode)
+ && TREE_CODE (USE_FROM_PTR (linknode)) == SSA_NAME)
+ {
+ tree var = USE_FROM_PTR (linknode);
+ gcc_assert (var->ssa_name.fast_iteration_depth == 0
+ && (var->ssa_name.active_iterated_stmt == NULL
+ || (var->ssa_name.active_iterated_stmt
+ == linknode->loc.stmt)));
+ }
+#endif
+
linknode->prev->next = linknode->next;
linknode->next->prev = linknode->prev;
linknode->prev = NULL;
@@ -349,9 +387,13 @@ end_readonly_imm_use_p (const imm_use_iterator *imm)
inline use_operand_p
first_readonly_imm_use (imm_use_iterator *imm, tree var)
{
+#if defined ENABLE_GIMPLE_CHECKING
+ var->ssa_name.fast_iteration_depth++;
+#endif
imm->end_p = &(SSA_NAME_IMM_USE_NODE (var));
imm->imm_use = imm->end_p->next;
imm->next_stmt_use = imm->imm_use->next;
+ imm->name = var;
if (end_readonly_imm_use_p (imm))
return NULL_USE_OPERAND_P;
return imm->imm_use;
@@ -846,8 +888,11 @@ end_imm_use_stmt_p (const imm_use_iterator *imm)
placeholder node from the list. */
inline void
-end_imm_use_stmt_traverse (imm_use_iterator *)
+end_imm_use_stmt_traverse (imm_use_iterator * ARG_UNUSED (imm))
{
+#if defined ENABLE_GIMPLE_CHECKING
+ imm->name->ssa_name.active_iterated_stmt = NULL;
+#endif
}
/* Immediate use traversal of uses within a stmt require that all the
@@ -923,6 +968,10 @@ link_use_stmts_after (use_operand_p head, imm_use_iterator
*)
inline gimple *
first_imm_use_stmt (imm_use_iterator *imm, tree var)
{
+#if defined ENABLE_GIMPLE_CHECKING
+ gcc_assert (var->ssa_name.active_iterated_stmt == NULL
+ && var->ssa_name.fast_iteration_depth == 0);
+#endif
imm->end_p = &(SSA_NAME_IMM_USE_NODE (var));
imm->imm_use = imm->end_p->next;
imm->next_imm_name = NULL_USE_OPERAND_P;
@@ -930,12 +979,16 @@ first_imm_use_stmt (imm_use_iterator *imm, tree var)
/* next_stmt_use is used to point to the immediate use node after
the set of uses for the current stmt. */
imm->next_stmt_use = NULL_USE_OPERAND_P;
+ imm->name = var;
if (end_imm_use_stmt_p (imm))
return NULL;
imm->next_stmt_use = link_use_stmts_after (imm->imm_use, imm)->next;
+#if defined ENABLE_GIMPLE_CHECKING
+ var->ssa_name.active_iterated_stmt = USE_STMT (imm->imm_use);
+#endif
return USE_STMT (imm->imm_use);
}
@@ -948,6 +1001,9 @@ next_imm_use_stmt (imm_use_iterator *imm)
if (end_imm_use_stmt_p (imm))
return NULL;
+#if defined ENABLE_GIMPLE_CHECKING
+ imm->name->ssa_name.active_iterated_stmt = USE_STMT (imm->imm_use);
+#endif
imm->next_stmt_use = link_use_stmts_after (imm->imm_use, imm)->next;
return USE_STMT (imm->imm_use);
}
diff --git a/gcc/tree-core.h b/gcc/tree-core.h
index 145e758600e..a6e40c7497f 100644
--- a/gcc/tree-core.h
+++ b/gcc/tree-core.h
@@ -1717,6 +1717,10 @@ struct GTY(()) tree_ssa_name {
"!POINTER_TYPE_P (TREE_TYPE ((tree)&%1)) : 2"))) info;
/* Immediate uses list for this SSA_NAME. */
struct ssa_use_operand_t imm_uses;
+#if defined ENABLE_GIMPLE_CHECKING
+ gimple *active_iterated_stmt;
+ unsigned fast_iteration_depth;
+#endif
};
struct GTY(()) phi_arg_d {
diff --git a/gcc/tree-ssanames.cc b/gcc/tree-ssanames.cc
index dcf8da56272..3d915738c98 100644
--- a/gcc/tree-ssanames.cc
+++ b/gcc/tree-ssanames.cc
@@ -406,6 +406,10 @@ make_ssa_name_fn (struct function *fn, tree var, gimple
*stmt,
SSA_NAME_IN_FREE_LIST (t) = 0;
SSA_NAME_IS_DEFAULT_DEF (t) = 0;
init_ssa_name_imm_use (t);
+#if defined ENABLE_GIMPLE_CHECKING
+ t->ssa_name.active_iterated_stmt = NULL;
+ t->ssa_name.fast_iteration_depth = 0;
+#endif
return t;
}
--
2.51.0
