};
/* Insert a new phi node for the dereference of PHI at basic_block
- BB with the virtual operands from USE_STMT. */
+ BB with the virtual operands from USE_STMT. The vuse for
+ the load will be set to OTHER_VUSE unless there is virtual op
+ phi for BB. */
static tree
phiprop_insert_phi (basic_block bb, gphi *phi, gimple *use_stmt,
struct phiprop_d *phivn, size_t n,
- bitmap dce_ssa_names)
+ bitmap dce_ssa_names, tree other_vuse)
{
tree res;
gphi *new_phi = NULL;
if (vphi)
vuse = PHI_ARG_DEF_FROM_EDGE (vphi, e);
else
- vuse = gimple_vuse (use_stmt);
+ vuse = other_vuse;
}
else
/* For the aggregate copy case updating virtual operands
incoming VUSE (up_vuse). If neither is present
make sure the def stmt of the virtual use is in a
different basic block dominating BB. When the def
- is an edge-inserted one we know it dominates us. */
-static bool
-can_handle_load (gimple *load_stmt, basic_block bb,
- gphi *vphi, tree up_vuse)
+ is an edge-inserted one we know it dominates us.
+ Returns the vuse to use for the inserting. NULL_TREE
+ is returned when we can't do the insert. */
+
+static tree
+can_handle_load (gimple *load_stmt,
+ basic_block bb,
+ gphi *vphi, tree up_vuse, bool aggregate)
{
tree vuse = gimple_vuse (load_stmt);
- if (vphi)
- return vuse == gimple_phi_result (vphi);
- if (up_vuse)
- return vuse == up_vuse;
- gimple *def_stmt = SSA_NAME_DEF_STMT (vuse);
/* If the load does not have a store beforehand,
then we can do the load in conditional. */
if (SSA_NAME_IS_DEFAULT_DEF (vuse))
- return true;
- if (gimple_bb (def_stmt) != bb
+ {
+ /* For loads that have no stores before, there should be no
+ vphi. */
+ gcc_checking_assert (!vphi);
+ /* The common vuse is the same as the default or there is none. */
+ gcc_checking_assert (!up_vuse || up_vuse == vuse);
+ return vuse;
+ }
+
+ /* If we have a vphi, then that needs to be end point.
+ If we have a common incoming vuse, that needs to be the end point. */
+ tree expected_vuse = NULL_TREE;
+ if (vphi)
+ expected_vuse = gimple_phi_result (vphi);
+ else if (up_vuse)
+ expected_vuse = up_vuse;
+
+ /* If the vuse on the load is the same as the expected vuse,
+ there are no stores inbetween. */
+ if (vuse == expected_vuse)
+ return vuse;
+ /* Try to see if the store does not effect the load. */
+ gimple *other_store = SSA_NAME_DEF_STMT (vuse);
+ /* Only handling the case where the store is in the same
+ bb as the phi. */
+ if (gimple_bb (other_store) == bb)
+ {
+ /* For aggregates, skipping the store is too
+ hard to handle as you need to check for loads
+ and it is not worth the extra checks. */
+ if (aggregate)
+ return NULL_TREE;
+ tree src = gimple_assign_rhs1 (load_stmt);
+ ao_ref read;
+ ao_ref_init (&read, src);
+ if (stmt_may_clobber_ref_p_1 (other_store, &read, false))
+ return NULL_TREE;
+ vuse = gimple_vuse (other_store);
+ /* If that skipped store was the first store in program,
+ then we can do the load conditional. */
+ if (SSA_NAME_IS_DEFAULT_DEF (vuse))
+ {
+ /* For loads that have no stores before, there should be no
+ vphi. */
+ gcc_checking_assert (!vphi);
+ /* The common vuse is the same as the default or there is none. */
+ gcc_checking_assert (!up_vuse || up_vuse == vuse);
+ return vuse;
+ }
+ other_store = SSA_NAME_DEF_STMT (vuse);
+ /* If the new vuse (after skipping) is the same as expected
+ then that is the vuse to return. */
+ if (vuse == expected_vuse)
+ return vuse;
+ if (gimple_bb (other_store) == bb)
+ return NULL_TREE;
+ }
+
+ /* If there was no an expected vuse then see if the vuse dominates the phi of
+ the address. */
+ if (!expected_vuse
&& dominated_by_p (CDI_DOMINATORS,
- bb, gimple_bb (def_stmt)))
- return true;
- return false;
+ bb, gimple_bb (other_store)))
+ return vuse;
+
+ return NULL_TREE;
}
/* Propagate between the phi node arguments of PHI in BB and phi result
&& !gimple_has_volatile_ops (use_stmt)))
continue;
- if (!can_handle_load (use_stmt, bb, vphi, up_vuse))
- continue;
-
bool aggregate = false;
if (!is_gimple_reg_type (TREE_TYPE (gimple_assign_lhs (use_stmt))))
aggregate = true;
+ tree other_vuse;
+ other_vuse = can_handle_load (use_stmt, bb, vphi, up_vuse, aggregate);
+ if (!other_vuse)
+ continue;
+
if ((canpossible_trap || aggregate)
&& !dom_info_available_p (cfun, CDI_POST_DOMINATORS))
calculate_dominance_info (CDI_POST_DOMINATORS);
goto next;
}
- phiprop_insert_phi (bb, phi, use_stmt, phivn, n, dce_ssa_names);
+ phiprop_insert_phi (bb, phi, use_stmt, phivn, n,
+ dce_ssa_names, other_vuse);
/* Remove old stmt. The phi and all of maybe its depedencies
will be removed later via simple_dce_from_worklist. */
else
{
tree vuse = gimple_vuse (use_stmt);
- res = phiprop_insert_phi (bb, phi, use_stmt, phivn, n, dce_ssa_names);
+ res = phiprop_insert_phi (bb, phi, use_stmt, phivn, n,
+ dce_ssa_names, other_vuse);
type = TREE_TYPE (res);
/* Remember the value we created for *ptr. */
projects / thirdparty / gcc.git / commitdiff
