[PATCH] Revert Revert r238497 because of PR 71961.

This patch reverts the change for PR 71902 since it causes 178.gagel
miscompile in spec2000 as reported in PR 71961 which was observed in
x86_64, aarch64, powerpc64.

gcc/fortran/ChangeLog:

2016-07-28  Renlin Li  <renlin.li@arm.com>

	Revert
	2016-07-19  Thomas Koenig  <tkoenig@gcc.gnu.org>

	PR fortran/71902
	* dependency.c (gfc_check_dependency): Use dep_ref.  Handle case
	if identical is true and two array element references differ.
	(gfc_dep_resovler):  Move most of the code to dep_ref.
	(dep_ref):  New function.
	* frontend-passes.c (realloc_string_callback):  Name temporary
	variable "realloc_string".

gcc/testsuite/ChangeLog:

2016-07-28  Renlin Li  <renlin.li@arm.com>

	Revert
	2016-07-19  Thomas Koenig  <tkoenig@gcc.gnu.org>

	PR fortran/71902
	* gfortran.dg/dependency_47.f90:  New test.

From-SVN: r238815

gcc/fortran/ChangeLog

+2016-07-28  Renlin Li  <renlin.li@arm.com>
+
+	Revert
+	2016-07-19  Thomas Koenig  <tkoenig@gcc.gnu.org>
+
+	PR fortran/71902
+	* dependency.c (gfc_check_dependency): Use dep_ref.  Handle case
+	if identical is true and two array element references differ.
+	(gfc_dep_resovler):  Move most of the code to dep_ref.
+	(dep_ref):  New function.
+	* frontend-passes.c (realloc_string_callback):  Name temporary
+	variable "realloc_string".
+
 2016-07-26  Steven G. Kargl  <kargl@gcc.gnu.org>
 
 	PR fortran/71862

gcc/fortran/dependency.c

@@ -54,8 +54,6 @@ enum gfc_dependency
 static gfc_dependency check_section_vs_section (gfc_array_ref *,
 						gfc_array_ref *, int);
 
-static gfc_dependency dep_ref (gfc_ref *, gfc_ref *, gfc_reverse *);
-
 /* Returns 1 if the expr is an integer constant value 1, 0 if it is not or
    def if the value could not be determined.  */
 
@@ -1318,33 +1316,13 @@ gfc_check_dependency (gfc_expr *expr1, gfc_expr *expr2, bool identical)
 	  return 0;
 	}
 
+      if (identical)
+	return 1;
+
       /* Identical and disjoint ranges return 0,
 	 overlapping ranges return 1.  */
       if (expr1->ref && expr2->ref)
-	{
-	  gfc_dependency dep;
-	  dep = dep_ref (expr1->ref, expr2->ref, NULL);
-	  switch (dep)
-	    {
-	    case GFC_DEP_EQUAL:
-	      return identical;
-
-	    case GFC_DEP_FORWARD:
-	      return 0;
-
-	    case GFC_DEP_BACKWARD:
-	      return 1;
-
-	    case GFC_DEP_OVERLAP:
-	      return 1;
-
-	    case GFC_DEP_NODEP:
-	      return 0;
-
-	    default:
-	      gcc_unreachable();
-	    }
-	}
+	return gfc_dep_resolver (expr1->ref, expr2->ref, NULL);
 
       return 1;
 
@@ -2074,39 +2052,11 @@ ref_same_as_full_array (gfc_ref *full_ref, gfc_ref *ref)
    	2 : array references are overlapping but reversal of one or
 	    more dimensions will clear the dependency.
    	1 : array references are overlapping.
-   	0 : array references are identical or can be handled in a forward loop.  */
+   	0 : array references are identical or not overlapping.  */
 
 int
 gfc_dep_resolver (gfc_ref *lref, gfc_ref *rref, gfc_reverse *reverse)
 {
-  enum gfc_dependency dep;
-  dep = dep_ref (lref, rref, reverse);
-  switch (dep)
-    {
-    case GFC_DEP_EQUAL:
-      return 0;
-
-    case GFC_DEP_FORWARD:
-      return 0;
-
-    case GFC_DEP_BACKWARD:
-      return 2;
-
-    case GFC_DEP_OVERLAP:
-      return 1;
-
-    case GFC_DEP_NODEP:
-      return 0;
-
-    default:
-      gcc_unreachable();
-    }
-}
-
-
-static gfc_dependency
-dep_ref (gfc_ref *lref, gfc_ref *rref, gfc_reverse *reverse)
-{
   int n;
   int m;
   gfc_dependency fin_dep;
@@ -2129,22 +2079,21 @@ dep_ref (gfc_ref *lref, gfc_ref *rref, gfc_reverse *reverse)
 	  /* The two ranges can't overlap if they are from different
 	     components.  */
 	  if (lref->u.c.component != rref->u.c.component)
-	    return GFC_DEP_NODEP;
+	    return 0;
 	  break;
 
 	case REF_SUBSTRING:
 	  /* Substring overlaps are handled by the string assignment code
 	     if there is not an underlying dependency.  */
-
-	  return fin_dep == GFC_DEP_ERROR ? GFC_DEP_NODEP : fin_dep;
+	  return (fin_dep == GFC_DEP_OVERLAP) ? 1 : 0;
 
 	case REF_ARRAY:
 
 	  if (ref_same_as_full_array (lref, rref))
-	    return GFC_DEP_EQUAL;
+	    return 0;
 
 	  if (ref_same_as_full_array (rref, lref))
-	    return GFC_DEP_EQUAL;
+	    return 0;
 
 	  if (lref->u.ar.dimen != rref->u.ar.dimen)
 	    {
@@ -2155,7 +2104,7 @@ dep_ref (gfc_ref *lref, gfc_ref *rref, gfc_reverse *reverse)
 		fin_dep = gfc_full_array_ref_p (lref, NULL) ? GFC_DEP_EQUAL
 							    : GFC_DEP_OVERLAP;
 	      else
-		return GFC_DEP_OVERLAP;
+		return 1;
 	      break;
 	    }
 
@@ -2199,7 +2148,7 @@ dep_ref (gfc_ref *lref, gfc_ref *rref, gfc_reverse *reverse)
 
 	      /* If any dimension doesn't overlap, we have no dependency.  */
 	      if (this_dep == GFC_DEP_NODEP)
-		return GFC_DEP_NODEP;
+		return 0;
 
 	      /* Now deal with the loop reversal logic:  This only works on
 		 ranges and is activated by setting
@@ -2266,7 +2215,7 @@ dep_ref (gfc_ref *lref, gfc_ref *rref, gfc_reverse *reverse)
 	  /* Exactly matching and forward overlapping ranges don't cause a
 	     dependency.  */
 	  if (fin_dep < GFC_DEP_BACKWARD)
-	    return fin_dep == GFC_DEP_ERROR ? GFC_DEP_NODEP : fin_dep;
+	    return 0;
 
 	  /* Keep checking.  We only have a dependency if
 	     subsequent references also overlap.  */
@@ -2284,7 +2233,7 @@ dep_ref (gfc_ref *lref, gfc_ref *rref, gfc_reverse *reverse)
 
   /* Assume the worst if we nest to different depths.  */
   if (lref || rref)
-    return GFC_DEP_OVERLAP;
+    return 1;
 
-  return fin_dep;
+  return fin_dep == GFC_DEP_OVERLAP;
 }

gcc/fortran/frontend-passes.c

@@ -185,7 +185,7 @@ realloc_string_callback (gfc_code **c, int *walk_subtrees ATTRIBUTE_UNUSED,
   current_code = c;
   inserted_block = NULL;
   changed_statement = NULL;
-  n = create_var (expr2, "realloc_string");
+  n = create_var (expr2, "trim");
   co->expr2 = n;
   return 0;
 }

gcc/testsuite/ChangeLog

+2016-07-28  Renlin Li  <renlin.li@arm.com>
+
+	Revert
+	2016-07-19  Thomas Koenig  <tkoenig@gcc.gnu.org>
+
+	PR fortran/71902
+	* gfortran.dg/dependency_47.f90:  New test.
+
 2016-07-28  Martin Liska  <mliska@suse.cz>
 
 	PR gcov-profile/68025

gcc/testsuite/gfortran.dg/dependency_47.f90

-! { dg-do compile }
-! Make sure there is only one instance of a temporary variable here.
-! { dg-options "-fdump-tree-original" }
-
-SUBROUTINE prtdata(ilen)
-  INTEGER :: ilen
-  character(len=ilen), allocatable :: cline(:)
-  allocate(cline(2))
-  cline(1) = 'a'
-  cline(1)(2:3) = cline(1)(1:2)
-  cline(2) = cline(1)
-  print *,c
-END SUBROUTINE prtdata
-! { dg-final { scan-tree-dump-not "__var_2" "original" } }
-! { dg-final { scan-tree-dump-times "__var_1" 3 "original" } }