re PR tree-optimization/56933 (Vectorizer missing read-write dependency for interleaved accesses)

2013-04-15  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/56933
	* tree-vectorizer.h (struct _stmt_vec_info): Remove read_write_dep
	member.
	(GROUP_READ_WRITE_DEPENDENCE): Remove.
	(STMT_VINFO_GROUP_READ_WRITE_DEPENDENCE): Likewise.
	* tree-vect-data-refs.c (vect_analyze_group_access): Move
	dependence check ...
	vect_analyze_data_ref_dependence (vect_analyze_data_ref_dependence):
	... here.
	* tree-vect-stmts.c (new_stmt_vec_info): Do not initialize
	GROUP_READ_WRITE_DEPENDENCE.

	* gcc.dg/vect/pr56933.c: New testcase.

From-SVN: r197972

6 files changed, 87 insertions, 26 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index fd1731e..db1b373 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,17 @@
+2013-04-15  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/56933
+	* tree-vectorizer.h (struct _stmt_vec_info): Remove read_write_dep
+	member.
+	(GROUP_READ_WRITE_DEPENDENCE): Remove.
+	(STMT_VINFO_GROUP_READ_WRITE_DEPENDENCE): Likewise.
+	* tree-vect-data-refs.c (vect_analyze_group_access): Move
+	dependence check ...
+	vect_analyze_data_ref_dependence (vect_analyze_data_ref_dependence):
+	... here.
+	* tree-vect-stmts.c (new_stmt_vec_info): Do not initialize
+	GROUP_READ_WRITE_DEPENDENCE.
+
 2013-04-15  Andreas Krebbel  <Andreas.Krebbel@de.ibm.com>
 
 	* emit-rtl.c (reset_all_used_flags): New function.
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index efc3ded..4613593 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2013-04-15  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/56933
+	* gcc.dg/vect/pr56933.c: New testcase.
+
 2013-04-15  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
 
 	* gcc.target/arm/anddi3-opt.c: New test.
diff --git a/gcc/testsuite/gcc.dg/vect/pr56933.c b/gcc/testsuite/gcc.dg/vect/pr56933.c
new file mode 100644
index 0000000..93a7da2
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/pr56933.c
@@ -0,0 +1,40 @@
+/* { dg-do run } */
+
+extern void abort (void);
+void __attribute__((noinline,noclone))
+foo (double *b, double *d, double *f)
+{
+  int i;
+  for (i = 0; i < 1024; i++)
+    {
+      d[2*i] = 2. * d[2*i];
+      d[2*i+1] = 4. * d[2*i+1];
+      b[i] = d[2*i] - 1.;
+      f[i] = d[2*i+1] + 2.;
+    }
+}
+int main()
+{
+  double b[1024], d[2*1024], f[1024];
+  int i;
+  for (i = 0; i < 2*1024; i++)
+    d[i] = 1.;
+  foo (b, d, f);
+  for (i = 0; i < 1024; i+= 2)
+    {
+      if (d[2*i] != 2.)
+	abort ();
+      if (d[2*i+1] != 4.)
+	abort ();
+    }
+  for (i = 0; i < 1024; i++)
+    {
+      if (b[i] != 1.)
+	abort ();
+      if (f[i] != 6.)
+	abort ();
+    }
+  return 0;
+}
+
+/* { dg-final { cleanup-tree-dump "vect" } } */
diff --git a/gcc/tree-vect-data-refs.c b/gcc/tree-vect-data-refs.c
index 64f2a8b..1fe5047 100644
--- a/gcc/tree-vect-data-refs.c
+++ b/gcc/tree-vect-data-refs.c
@@ -341,14 +341,34 @@ vect_analyze_data_ref_dependence (struct data_dependence_relation *ddr,
 	      dump_generic_expr (MSG_NOTE, TDF_SLIM, DR_REF (drb));
 	    }
 
-          /* For interleaving, mark that there is a read-write dependency if
-             necessary.  We check before that one of the data-refs is store.  */
-          if (DR_IS_READ (dra))
-            GROUP_READ_WRITE_DEPENDENCE (stmtinfo_a) = true;
-	  else
-            {
-              if (DR_IS_READ (drb))
-                GROUP_READ_WRITE_DEPENDENCE (stmtinfo_b) = true;
+	  /* When we perform grouped accesses and perform implicit CSE
+	     by detecting equal accesses and doing disambiguation with
+	     runtime alias tests like for
+	        .. = a[i];
+		.. = a[i+1];
+		a[i] = ..;
+		a[i+1] = ..;
+		*p = ..;
+		.. = a[i];
+		.. = a[i+1];
+	     where we will end up loading { a[i], a[i+1] } once, make
+	     sure that inserting group loads before the first load and
+	     stores after the last store will do the right thing.  */
+	  if ((STMT_VINFO_GROUPED_ACCESS (stmtinfo_a)
+	       && GROUP_SAME_DR_STMT (stmtinfo_a))
+	      || (STMT_VINFO_GROUPED_ACCESS (stmtinfo_b)
+		  && GROUP_SAME_DR_STMT (stmtinfo_b)))
+	    {
+	      gimple earlier_stmt;
+	      earlier_stmt = get_earlier_stmt (DR_STMT (dra), DR_STMT (drb));
+	      if (DR_IS_WRITE
+		    (STMT_VINFO_DATA_REF (vinfo_for_stmt (earlier_stmt))))
+		{
+		  if (dump_enabled_p ())
+		    dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
+				     "READ_WRITE dependence in interleaving.");
+		  return true;
+		}
 	    }
 
 	  continue;
@@ -2097,17 +2117,6 @@ vect_analyze_group_access (struct data_reference *dr)
                   return false;
                 }
 
-              /* Check that there is no load-store dependencies for this loads
-                 to prevent a case of load-store-load to the same location.  */
-              if (GROUP_READ_WRITE_DEPENDENCE (vinfo_for_stmt (next))
-                  || GROUP_READ_WRITE_DEPENDENCE (vinfo_for_stmt (prev)))
-                {
-                  if (dump_enabled_p ())
-                    dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location, 
-                                     "READ_WRITE dependence in interleaving.");
-                  return false;
-                }
-
               /* For load use the same data-ref load.  */
               GROUP_SAME_DR_STMT (vinfo_for_stmt (next)) = prev;
 
diff --git a/gcc/tree-vect-stmts.c b/gcc/tree-vect-stmts.c
index 3590e39..bdd4d64 100644
--- a/gcc/tree-vect-stmts.c
+++ b/gcc/tree-vect-stmts.c
@@ -5962,7 +5962,6 @@ new_stmt_vec_info (gimple stmt, loop_vec_info loop_vinfo,
   GROUP_STORE_COUNT (res) = 0;
   GROUP_GAP (res) = 0;
   GROUP_SAME_DR_STMT (res) = NULL;
-  GROUP_READ_WRITE_DEPENDENCE (res) = false;
 
   return res;
 }
diff --git a/gcc/tree-vectorizer.h b/gcc/tree-vectorizer.h
index 0f1a02a..8071149 100644
--- a/gcc/tree-vectorizer.h
+++ b/gcc/tree-vectorizer.h
@@ -460,10 +460,6 @@ typedef struct _stmt_vec_info {
   /* Stmt is part of some pattern (computation idiom)  */
   bool in_pattern_p;
 
-  /* For loads only, if there is a store with the same location, this field is
-     TRUE.  */
-  bool read_write_dep;
-
   /* The stmt to which this info struct refers to.  */
   gimple stmt;
 
@@ -589,7 +585,6 @@ typedef struct _stmt_vec_info {
 #define STMT_VINFO_GROUP_STORE_COUNT(S)    (S)->store_count
 #define STMT_VINFO_GROUP_GAP(S)            (S)->gap
 #define STMT_VINFO_GROUP_SAME_DR_STMT(S)   (S)->same_dr_stmt
-#define STMT_VINFO_GROUP_READ_WRITE_DEPENDENCE(S)  (S)->read_write_dep
 #define STMT_VINFO_GROUPED_ACCESS(S)      ((S)->first_element != NULL && (S)->data_ref_info)
 #define STMT_VINFO_LOOP_PHI_EVOLUTION_PART(S) (S)->loop_phi_evolution_part
 
@@ -599,7 +594,6 @@ typedef struct _stmt_vec_info {
 #define GROUP_STORE_COUNT(S)            (S)->store_count
 #define GROUP_GAP(S)                    (S)->gap
 #define GROUP_SAME_DR_STMT(S)           (S)->same_dr_stmt
-#define GROUP_READ_WRITE_DEPENDENCE(S)  (S)->read_write_dep
 
 #define STMT_VINFO_RELEVANT_P(S)          ((S)->relevant != vect_unused_in_scope)