ddg.c (walk_mems_2): Moved from alias.c, use may_alias_p instead of alias_sets_conflict_p.

2010-08-09  Bingfeng Mei  <bmei@broadcom.com>

	* ddg.c (walk_mems_2): Moved from alias.c, use may_alias_p instead of
	alias_sets_conflict_p.
	(walk_mems_1): Moved from alias.c.
	(insns_may_alias_p): New function, originally insn_alias_sets_conflict_p
	in alias.c. 
        (add_inter_loop_mem_dep): Use insns_may_alias_p now.
        * cse.c (cse_insn): New argument in calling nonoverlapping_memrefs_p.
        * alias.c (walk_mems_2): Moved to ddg.c.
	(walk_mems_1): Ditto.
	(insn_alias_sets_conflict_p): Renamed to insns_may_alias_p and moved
	to ddg.c.
	(nonoverlapping_memrefs_p): Add flag to guard offset-based memory
	disambiguation.
	*(may_alias_p): New function to check whether two memory expression
	may alias or not. Currently used in buidling inter-iteration memory
	dependence.
	*alias.h (nonoverlapping_memrefs_p): New flag as third argument.
	(insn_alias_sets_conflict_p): Removed
	*rtl.h (may_alias_p): New function prototype.

From-SVN: r163037

1 files changed, 38 insertions, 1 deletions

diff --git a/gcc/ddg.c b/gcc/ddg.c
index 0a20ed61291..88aaf9bb2e4 100644
--- a/gcc/ddg.c
+++ b/gcc/ddg.c
@@ -348,12 +348,49 @@ build_inter_loop_deps (ddg_ptr g)
 }
 
 
+static int
+walk_mems_2 (rtx *x, rtx mem)
+{
+  if (MEM_P (*x))
+    {
+      if (may_alias_p (*x, mem))
+        return 1;
+
+      return -1;
+    }
+  return 0;
+}
+
+static int
+walk_mems_1 (rtx *x, rtx *pat)
+{
+  if (MEM_P (*x))
+    {
+      /* Visit all MEMs in *PAT and check indepedence.  */
+      if (for_each_rtx (pat, (rtx_function) walk_mems_2, *x))
+        /* Indicate that dependence was determined and stop traversal.  */
+        return 1;
+
+      return -1;
+    }
+  return 0;
+}
+
+/* Return 1 if two specified instructions have mem expr with conflict alias sets*/
+static int
+insns_may_alias_p (rtx insn1, rtx insn2)
+{
+  /* For each pair of MEMs in INSN1 and INSN2 check their independence.  */
+  return  for_each_rtx (&PATTERN (insn1), (rtx_function) walk_mems_1,
+			 &PATTERN (insn2));
+}
+
 /* Given two nodes, analyze their RTL insns and add inter-loop mem deps
    to ddg G.  */
 static void
 add_inter_loop_mem_dep (ddg_ptr g, ddg_node_ptr from, ddg_node_ptr to)
 {
-  if (!insn_alias_sets_conflict_p (from->insn, to->insn))
+  if (!insns_may_alias_p (from->insn, to->insn))
     /* Do not create edge if memory references have disjoint alias sets.  */
     return;