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-rw-r--r--gcc/tree-ssa.c315
1 files changed, 1 insertions, 314 deletions
diff --git a/gcc/tree-ssa.c b/gcc/tree-ssa.c
index e23e665..93b5480 100644
--- a/gcc/tree-ssa.c
+++ b/gcc/tree-ssa.c
@@ -285,7 +285,7 @@ verify_use (basic_block bb, basic_block def_bb, use_operand_p use_p,
{
fprintf (stderr, "for SSA_NAME: ");
print_generic_expr (stderr, ssa_name, TDF_VOPS);
- fprintf (stderr, "in statement:\n");
+ fprintf (stderr, " in statement:\n");
print_generic_stmt (stderr, stmt, TDF_VOPS);
}
@@ -1028,319 +1028,6 @@ walk_use_def_chains (tree var, walk_use_def_chains_fn fn, void *data,
}
}
-
-/* Replaces VAR with REPL in memory reference expression *X in
- statement STMT at use location USE_P. Return TRUE if Anything was done. */
-
-static bool
-propagate_into_addr (tree stmt, use_operand_p use_p, tree *x, tree repl)
-{
- tree new_var, ass_stmt, addr_var;
- basic_block bb;
- block_stmt_iterator bsi;
-
- /* There is nothing special to handle in the other cases. */
- if (TREE_CODE (repl) != ADDR_EXPR)
- return false;
- addr_var = TREE_OPERAND (repl, 0);
-
- while (handled_component_p (*x)
- || TREE_CODE (*x) == REALPART_EXPR
- || TREE_CODE (*x) == IMAGPART_EXPR)
- x = &TREE_OPERAND (*x, 0);
-
- /* Heres a hack but since KRPhinodes is going away soon, Im not going to
- sweat it. */
- if (TREE_CODE (*x) != INDIRECT_REF
- || &(TREE_OPERAND (*x, 0)) != use_p->use) /* HACK ALERT. */
- return false;
-
- if (TREE_TYPE (*x) == TREE_TYPE (addr_var))
- {
- *x = addr_var;
- mark_new_vars_to_rename (stmt, vars_to_rename);
- return true;
- }
-
-
- /* Frontends sometimes produce expressions like *&a instead of a[0].
- Create a temporary variable to handle this case. */
- ass_stmt = build2 (MODIFY_EXPR, void_type_node, NULL_TREE, repl);
- new_var = duplicate_ssa_name (USE_FROM_PTR (use_p), ass_stmt);
- TREE_OPERAND (*x, 0) = new_var;
- TREE_OPERAND (ass_stmt, 0) = new_var;
-
- bb = bb_for_stmt (stmt);
- tree_block_label (bb);
- bsi = bsi_after_labels (bb);
- bsi_insert_after (&bsi, ass_stmt, BSI_NEW_STMT);
-
- mark_new_vars_to_rename (stmt, vars_to_rename);
- return true;
-}
-
-/* Replaces immediate uses of VAR by REPL. */
-
-static void
-replace_immediate_uses (tree var, tree repl)
-{
- tree stmt;
- bool mark_new_vars;
- use_operand_p imm_use;
- imm_use_iterator imm_iter;
-
- FOR_EACH_IMM_USE_SAFE (imm_use, imm_iter, var)
- {
- stmt = USE_STMT (imm_use);
-
- if (TREE_CODE (stmt) == PHI_NODE)
- {
- int index = PHI_ARG_INDEX_FROM_USE (imm_use);
-#ifdef ENABLE_CHECKING
- gcc_assert (&(PHI_ARG_IMM_USE_NODE (stmt, index)) == imm_use);
-#endif
- SET_USE (imm_use, repl);
- if (TREE_CODE (repl) == SSA_NAME
- && PHI_ARG_EDGE (stmt, index)->flags & EDGE_ABNORMAL)
- SSA_NAME_OCCURS_IN_ABNORMAL_PHI (repl) = 1;
- continue;
- }
-
- gcc_assert (!stmt_modified_p (stmt));
-
- mark_new_vars = false;
- if (is_gimple_reg (SSA_NAME_VAR (var)))
- {
- bool propagated = false;
- if (TREE_CODE (stmt) == MODIFY_EXPR)
- {
- if (TREE_CODE (repl) == ADDR_EXPR)
- {
- propagated =
- propagate_into_addr (stmt, imm_use, &TREE_OPERAND (stmt, 0),
- repl);
- if (!propagated)
- propagated =
- propagate_into_addr (stmt, imm_use,
- &TREE_OPERAND (stmt, 1), repl);
- }
- }
- if (!propagated)
- propagate_value (imm_use, repl);
- mark_new_vars = POINTER_TYPE_P (TREE_TYPE (repl));
- }
- else
- propagate_value (imm_use, repl);
-
- /* FIXME. If REPL is a constant, we need to fold STMT.
- However, fold_stmt wants a pointer to the statement, because
- it may happen that it needs to replace the whole statement
- with a new expression. Since the current def-use machinery
- does not return pointers to statements, we call fold_stmt
- with the address of a local temporary, if that call changes
- the temporary then we fallback on looking for a proper
- pointer to STMT by scanning STMT's basic block.
-
- Note that all this will become unnecessary soon. This
- pass is being replaced with a proper copy propagation pass
- for 4.1 (dnovillo, 2004-09-17). */
- if (TREE_CODE (repl) != SSA_NAME)
- {
- tree tmp = stmt;
- fold_stmt (&tmp);
- mark_new_vars = true;
- if (tmp != stmt)
- {
- block_stmt_iterator si = bsi_for_stmt (stmt);
- mark_new_vars_to_rename (tmp, vars_to_rename);
- bsi_replace (&si, tmp, true);
- stmt = bsi_stmt (si);
- }
- }
-
- /* If REPL is a pointer, it may have different memory tags associated
- with it. For instance, VAR may have had a name tag while REPL
- only had a type tag. In these cases, the virtual operands (if
- any) in the statement will refer to different symbols which need
- to be renamed. */
- if (mark_new_vars)
- mark_new_vars_to_rename (stmt, vars_to_rename);
- else
- update_stmt (stmt);
- }
-
-}
-
-/* Gets the value VAR is equivalent to according to EQ_TO. */
-
-static tree
-get_eq_name (tree *eq_to, tree var)
-{
- unsigned ver;
- tree val = var;
-
- while (TREE_CODE (val) == SSA_NAME)
- {
- ver = SSA_NAME_VERSION (val);
- if (!eq_to[ver])
- break;
-
- val = eq_to[ver];
- }
-
- while (TREE_CODE (var) == SSA_NAME)
- {
- ver = SSA_NAME_VERSION (var);
- if (!eq_to[ver])
- break;
-
- var = eq_to[ver];
- eq_to[ver] = val;
- }
-
- return val;
-}
-
-/* Checks whether phi node PHI is redundant and if it is, records the ssa name
- its result is redundant to to EQ_TO array. */
-
-static void
-check_phi_redundancy (tree phi, tree *eq_to)
-{
- tree val = NULL_TREE, def, res = PHI_RESULT (phi), stmt;
- unsigned i, ver = SSA_NAME_VERSION (res);
- imm_use_iterator imm_iter;
- use_operand_p use_p;
-
- /* It is unlikely that such large phi node would be redundant. */
- if (PHI_NUM_ARGS (phi) > 16)
- return;
-
- for (i = 0; i < (unsigned) PHI_NUM_ARGS (phi); i++)
- {
- def = PHI_ARG_DEF (phi, i);
-
- if (TREE_CODE (def) == SSA_NAME)
- {
- def = get_eq_name (eq_to, def);
- if (def == res)
- continue;
- }
-
- if (val
- && !operand_equal_for_phi_arg_p (val, def))
- return;
-
- val = def;
- }
-
- /* At least one of the arguments should not be equal to the result, or
- something strange is happening. */
- gcc_assert (val);
-
- if (get_eq_name (eq_to, res) == val)
- return;
-
- if (!may_propagate_copy (res, val))
- return;
-
- eq_to[ver] = val;
-
- FOR_EACH_IMM_USE_FAST (use_p, imm_iter, res)
- {
- stmt = USE_STMT (use_p);
- if (TREE_CODE (stmt) == PHI_NODE)
- check_phi_redundancy (stmt, eq_to);
- }
-}
-
-/* Removes redundant phi nodes.
-
- A redundant PHI node is a PHI node where all of its PHI arguments
- are the same value, excluding any PHI arguments which are the same
- as the PHI result.
-
- A redundant PHI node is effectively a copy, so we forward copy propagate
- which removes all uses of the destination of the PHI node then
- finally we delete the redundant PHI node.
-
- Note that if we can not copy propagate the PHI node, then the PHI
- will not be removed. Thus we do not have to worry about dependencies
- between PHIs and the problems serializing PHIs into copies creates.
-
- The most important effect of this pass is to remove degenerate PHI
- nodes created by removing unreachable code. */
-
-void
-kill_redundant_phi_nodes (void)
-{
- tree *eq_to;
- unsigned i, old_num_ssa_names;
- basic_block bb;
- tree phi, repl, stmt;
-
- /* The EQ_TO[VER] holds the value by that the ssa name VER should be
- replaced. If EQ_TO[VER] is ssa name and it is decided to replace it by
- other value, it may be necessary to follow the chain till the final value.
- We perform path shortening (replacing the entries of the EQ_TO array with
- heads of these chains) whenever we access the field to prevent quadratic
- complexity (probably would not occur in practice anyway, but let us play
- it safe). */
- eq_to = xcalloc (num_ssa_names, sizeof (tree));
-
- old_num_ssa_names = num_ssa_names;
-
- FOR_EACH_BB (bb)
- {
- for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
- check_phi_redundancy (phi, eq_to);
- }
-
- /* Now propagate the values. */
- for (i = 0; i < old_num_ssa_names; i++)
- {
- if (!ssa_name (i))
- continue;
-
- repl = get_eq_name (eq_to, ssa_name (i));
- if (repl != ssa_name (i))
- replace_immediate_uses (ssa_name (i), repl);
- }
-
- /* And remove the dead phis. */
- for (i = 0; i < old_num_ssa_names; i++)
- {
- if (!ssa_name (i))
- continue;
-
- repl = get_eq_name (eq_to, ssa_name (i));
- if (repl != ssa_name (i))
- {
- stmt = SSA_NAME_DEF_STMT (ssa_name (i));
- remove_phi_node (stmt, NULL_TREE);
- }
- }
-
- free (eq_to);
-}
-
-struct tree_opt_pass pass_redundant_phi =
-{
- "redphi", /* name */
- NULL, /* gate */
- kill_redundant_phi_nodes, /* execute */
- NULL, /* sub */
- NULL, /* next */
- 0, /* static_pass_number */
- TV_TREE_REDPHI, /* tv_id */
- PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */
- 0, /* properties_provided */
- 0, /* properties_destroyed */
- 0, /* todo_flags_start */
- TODO_dump_func | TODO_rename_vars
- | TODO_ggc_collect | TODO_verify_ssa, /* todo_flags_finish */
- 0 /* letter */
-};
/* Emit warnings for uninitialized variables. This is done in two passes.
generated by cgit v1.1 at 2025-05-30 18:17:44 +0000