[PATCH][COMMITTED] Revert r238497 because of PR 71961.

[Renlin Li <renlin dot li at foss dot arm dot com>]

Hi all,

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.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71961

As a consequence, I will reopen PR 71902: 
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71902

Regards,
Renlin Li


gcc/fortran/ChangeLog:
c
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.

diff --git a/gcc/fortran/dependency.c b/gcc/fortran/dependency.c
index a873dbe..f117de0 100644
--- a/gcc/fortran/dependency.c
+++ b/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;
 }
diff --git a/gcc/fortran/frontend-passes.c b/gcc/fortran/frontend-passes.c
index d333c68..a543ab2 100644
--- a/gcc/fortran/frontend-passes.c
+++ b/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;
 }
diff --git a/gcc/testsuite/gfortran.dg/dependency_47.f90 b/gcc/testsuite/gfortran.dg/dependency_47.f90
deleted file mode 100644
index eebc910..0000000
--- a/gcc/testsuite/gfortran.dg/dependency_47.f90
+++ /dev/null
@@ -1,15 +0,0 @@
-! { 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" } }