When Jeff did the DSE improvements I was reminded that PRE didn't
fold calls properly (aka not in-place). This results in unfolded
memory ops (not inlined or removed as do nothing for size zero).
The following finally fixes that.
Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to trunk.
Richard.
2017-05-12 Richard Biener <rguent...@suse.de>
* tree-ssa-sccvn.h (has_VN_INFO): Declare.
* tree-ssa-pre.c (eliminate_dom_walker::before_dom_children):
Fold all stmts not inplace.
* g++.dg/tree-ssa/ssa-dse-2.C: Adjust.
Index: gcc/testsuite/g++.dg/tree-ssa/ssa-dse-2.C
===================================================================
--- gcc/testsuite/g++.dg/tree-ssa/ssa-dse-2.C (revision 247965)
+++ gcc/testsuite/g++.dg/tree-ssa/ssa-dse-2.C (working copy)
@@ -54,6 +54,4 @@ fill_vec_av_set (av_set_t av)
}
/* { dg-final { scan-tree-dump-not "Trimming statement .head = -" "dse2" } } */
-/* { dg-final { scan-tree-dump "Deleted dead call: " "dse2" } } */
-
-
+/* { dg-final { scan-tree-dump-not "mem\[^\r\n\]*, 0\\);" "dse2" } } */
Index: gcc/tree-ssa-pre.c
===================================================================
--- gcc/tree-ssa-pre.c (revision 247965)
+++ gcc/tree-ssa-pre.c (working copy)
@@ -4645,30 +4645,51 @@ eliminate_dom_walker::before_dom_childre
&& TREE_CODE (gimple_assign_rhs1 (stmt)) == ADDR_EXPR)
recompute_tree_invariant_for_addr_expr (gimple_assign_rhs1 (stmt));
gimple *old_stmt = stmt;
- if (is_gimple_call (stmt))
+ gimple_stmt_iterator prev = gsi;
+ gsi_prev (&prev);
+ if (fold_stmt (&gsi))
{
- /* ??? Only fold calls inplace for now, this may create new
- SSA names which in turn will confuse free_scc_vn SSA name
- release code. */
- fold_stmt_inplace (&gsi);
- /* When changing a call into a noreturn call, cfg cleanup
- is needed to fix up the noreturn call. */
- if (!was_noreturn && gimple_call_noreturn_p (stmt))
- el_to_fixup.safe_push (stmt);
- }
- else
- {
- fold_stmt (&gsi);
- stmt = gsi_stmt (gsi);
- if ((gimple_code (stmt) == GIMPLE_COND
- && (gimple_cond_true_p (as_a <gcond *> (stmt))
- || gimple_cond_false_p (as_a <gcond *> (stmt))))
- || (gimple_code (stmt) == GIMPLE_SWITCH
- && TREE_CODE (gimple_switch_index (
- as_a <gswitch *> (stmt)))
- == INTEGER_CST))
- el_todo |= TODO_cleanup_cfg;
+ /* fold_stmt may have created new stmts inbetween
+ the previous stmt and the folded stmt. Mark
+ all defs created there as varying to not confuse
+ the SCCVN machinery as we're using that even during
+ elimination. */
+ if (gsi_end_p (prev))
+ prev = gsi_start_bb (b);
+ else
+ gsi_next (&prev);
+ if (gsi_stmt (prev) != gsi_stmt (gsi))
+ do
+ {
+ tree def;
+ ssa_op_iter dit;
+ FOR_EACH_SSA_TREE_OPERAND (def, gsi_stmt (prev),
+ dit, SSA_OP_ALL_DEFS)
+ /* As existing DEFs may move between stmts
+ we have to guard VN_INFO_GET. */
+ if (! has_VN_INFO (def))
+ VN_INFO_GET (def)->valnum = def;
+ if (gsi_stmt (prev) == gsi_stmt (gsi))
+ break;
+ gsi_next (&prev);
+ }
+ while (1);
}
+ stmt = gsi_stmt (gsi);
+ /* When changing a call into a noreturn call, cfg cleanup
+ is needed to fix up the noreturn call. */
+ if (!was_noreturn
+ && is_gimple_call (stmt) && gimple_call_noreturn_p (stmt))
+ el_to_fixup.safe_push (stmt);
+ /* When changing a condition or switch into one we know what
+ edge will be executed, schedule a cfg cleanup. */
+ if ((gimple_code (stmt) == GIMPLE_COND
+ && (gimple_cond_true_p (as_a <gcond *> (stmt))
+ || gimple_cond_false_p (as_a <gcond *> (stmt))))
+ || (gimple_code (stmt) == GIMPLE_SWITCH
+ && TREE_CODE (gimple_switch_index
+ (as_a <gswitch *> (stmt))) == INTEGER_CST))
+ el_todo |= TODO_cleanup_cfg;
/* If we removed EH side-effects from the statement, clean
its EH information. */
if (maybe_clean_or_replace_eh_stmt (old_stmt, stmt))
Index: gcc/tree-ssa-sccvn.h
===================================================================
--- gcc/tree-ssa-sccvn.h (revision 247965)
+++ gcc/tree-ssa-sccvn.h (working copy)
@@ -209,6 +209,7 @@ typedef struct vn_ssa_aux
enum vn_lookup_kind { VN_NOWALK, VN_WALK, VN_WALKREWRITE };
/* Return the value numbering info for an SSA_NAME. */
+bool has_VN_INFO (tree);
extern vn_ssa_aux_t VN_INFO (tree);
extern vn_ssa_aux_t VN_INFO_GET (tree);
tree vn_get_expr_for (tree);
