This "physically" separates forwprop and combining all stmts to
allow an easy lattice implementation.
Committed.
Richard.
2014-03-13 Richard Biener <rguent...@suse.de>
* tree-ssa-forwprop.c (ssa_forward_propagate_and_combine):
Split out combining with gimple_match_and_simplify to a
separate "pass". Implement a lattice.
Index: gcc/tree-ssa-forwprop.c
===================================================================
*** gcc/tree-ssa-forwprop.c (revision 208478)
--- gcc/tree-ssa-forwprop.c (working copy)
*************** along with GCC; see the file COPYING3.
*** 52,57 ****
--- 52,59 ----
#include "optabs.h"
#include "tree-ssa-propagate.h"
#include "tree-ssa-dom.h"
+ #include "tree-cfgcleanup.h"
+ #include "tree-into-ssa.h"
/* This pass propagates the RHS of assignment statements into use
sites of the LHS of the assignment. It's basically a specialized
*************** simplify_mult (gimple_stmt_iterator *gsi
*** 3571,3576 ****
--- 3573,3580 ----
}
+ static vec<tree> lattice;
+
/* Primitive "lattice" function for gimple_match_and_simplify to discard
matches on names whose definition contains abnormal SSA names. */
*************** static tree
*** 3578,3589 ****
fwprop_ssa_val (tree name)
{
if (TREE_CODE (name) == SSA_NAME
! /* ??? Instead match-and-simplify should make sure to not
! return a sequence that references abnormal SSA names. */
! && (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name)
! || (gimple_code (SSA_NAME_DEF_STMT (name)) != GIMPLE_PHI
! && stmt_references_abnormal_ssa_name (SSA_NAME_DEF_STMT (name)))))
! return NULL_TREE;
return name;
}
--- 3582,3593 ----
fwprop_ssa_val (tree name)
{
if (TREE_CODE (name) == SSA_NAME
! && SSA_NAME_VERSION (name) < lattice.length ())
! {
! tree val = lattice[SSA_NAME_VERSION (name)];
! if (val)
! return val;
! }
return name;
}
*************** ssa_forward_propagate_and_combine (void)
*** 3598,3603 ****
--- 3602,3665 ----
cfg_changed = false;
+ /* Combine stmts with the stmts defining their operands. Do that
+ in an order that guarantees visiting SSA defs before SSA uses. */
+ lattice.create (num_ssa_names);
+ lattice.quick_grow_cleared (num_ssa_names);
+ int *postorder = XNEWVEC (int, n_basic_blocks_for_fn (cfun));
+ int postorder_num = inverted_post_order_compute (postorder);
+ for (int i = 0; i < postorder_num; ++i)
+ {
+ bb = BASIC_BLOCK_FOR_FN (cfun, postorder[i]);
+ /* ??? Maybe want to handle degenerate PHIs to populate
+ the lattice more optimistically. */
+ for (gimple_stmt_iterator gsi = gsi_start_bb (bb);
+ !gsi_end_p (gsi); gsi_next (&gsi))
+ {
+ gimple stmt = gsi_stmt (gsi);
+
+ if (gimple_match_and_simplify (&gsi, fwprop_ssa_val))
+ {
+ stmt = gsi_stmt (gsi);
+ if (maybe_clean_or_replace_eh_stmt (stmt, stmt)
+ && gimple_purge_dead_eh_edges (bb))
+ cfg_changed = true;
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ {
+ fprintf (dump_file, "gimple_match_and_simplified to ");
+ print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
+ }
+ }
+
+ /* Fill up the lattice. */
+ if (gimple_assign_single_p (stmt))
+ {
+ tree lhs = gimple_assign_lhs (stmt);
+ tree rhs = gimple_assign_rhs1 (stmt);
+ if (TREE_CODE (lhs) == SSA_NAME)
+ {
+ if (TREE_CODE (rhs) == SSA_NAME)
+ lattice[SSA_NAME_VERSION (lhs)] = fwprop_ssa_val (rhs);
+ else if (is_gimple_min_invariant (rhs))
+ lattice[SSA_NAME_VERSION (lhs)] = rhs;
+ else
+ lattice[SSA_NAME_VERSION (lhs)] = lhs;
+ }
+ }
+ }
+ }
+ free (postorder);
+ lattice.release ();
+
+ /* ??? Code below doesn't expect non-renamed VOPs and the above
+ doesn't keep virtual operand form up-to-date. */
+ if (cfg_changed)
+ {
+ cleanup_tree_cfg ();
+ cfg_changed = false;
+ }
+ update_ssa (TODO_update_ssa_only_virtuals);
+
FOR_EACH_BB_FN (bb, cfun)
{
gimple_stmt_iterator gsi;
*************** ssa_forward_propagate_and_combine (void)
*** 3699,3719 ****
/* Mark stmt as potentially needing revisiting. */
gimple_set_plf (stmt, GF_PLF_1, false);
- if (gimple_match_and_simplify (&gsi, fwprop_ssa_val))
- {
- stmt = gsi_stmt (gsi);
- if (maybe_clean_or_replace_eh_stmt (stmt, stmt)
- && gimple_purge_dead_eh_edges (bb))
- cfg_changed = true;
- changed = true;
- if (dump_file && (dump_flags & TDF_DETAILS))
- {
- fprintf (dump_file, "gimple_match_and_simplified to ");
- print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
- }
- }
-
- if (!changed)
switch (gimple_code (stmt))
{
case GIMPLE_ASSIGN:
--- 3761,3766 ----
