re PR fortran/61780 (Wrong code when shifting elements of a multidimensional array)

2014-07-12  Paul Thomas  <pault@gcc.gnu.org>

	PR fortran/61780
	* dependency.c (gfc_dep_resolver): Index the 'reverse' array so
	that elements are skipped. This then correctly aligns 'reverse'
	with the scalarizer loops.

2014-07-12  Paul Thomas  <pault@gcc.gnu.org>

	PR fortran/61780
	* gfortran.dg/dependency_44.f90 : New test

From-SVN: r212486

gcc/fortran/ChangeLog

@@ -1,3 +1,10 @@
+2014-07-12  Paul Thomas  <pault@gcc.gnu.org>
+
+	PR fortran/61780
+	* dependency.c (gfc_dep_resolver): Index the 'reverse' array so
+	that elements are skipped. This then correctly aligns 'reverse'
+	with the scalarizer loops.
+
 2014-07-12  Tobias Burnus  <burnus@net-b.de>
 
 	PR fortran/61628

gcc/fortran/dependency.c

@@ -2023,6 +2023,7 @@ int
 gfc_dep_resolver (gfc_ref *lref, gfc_ref *rref, gfc_reverse *reverse)
 {
   int n;
+  int m;
   gfc_dependency fin_dep;
   gfc_dependency this_dep;
 
@@ -2072,6 +2073,8 @@ gfc_dep_resolver (gfc_ref *lref, gfc_ref *rref, gfc_reverse *reverse)
 	      break;
 	    }
 
+	  /* Index for the reverse array.  */
+	  m = -1;
 	  for (n=0; n < lref->u.ar.dimen; n++)
 	    {
 	      /* Handle dependency when either of array reference is vector
@@ -2118,38 +2121,44 @@ gfc_dep_resolver (gfc_ref *lref, gfc_ref *rref, gfc_reverse *reverse)
 		 The ability to reverse or not is set by previous conditions
 		 in this dimension.  If reversal is not activated, the
 		 value GFC_DEP_BACKWARD is reset to GFC_DEP_OVERLAP.  */
+
+	      /* Get the indexing right for the scalarizing loop. If this
+		 is an element, there is no corresponding loop.  */
+	      if (lref->u.ar.dimen_type[n] != DIMEN_ELEMENT)
+		m++;
+
 	      if (rref->u.ar.dimen_type[n] == DIMEN_RANGE
 		    && lref->u.ar.dimen_type[n] == DIMEN_RANGE)
 		{
 		  /* Set reverse if backward dependence and not inhibited.  */
-		  if (reverse && reverse[n] == GFC_ENABLE_REVERSE)
+		  if (reverse && reverse[m] == GFC_ENABLE_REVERSE)
-		    reverse[n] = (this_dep == GFC_DEP_BACKWARD) ?
+		    reverse[m] = (this_dep == GFC_DEP_BACKWARD) ?
-			         GFC_REVERSE_SET : reverse[n];
+			         GFC_REVERSE_SET : reverse[m];
 
 		  /* Set forward if forward dependence and not inhibited.  */
-		  if (reverse && reverse[n] == GFC_ENABLE_REVERSE)
+		  if (reverse && reverse[m] == GFC_ENABLE_REVERSE)
-		    reverse[n] = (this_dep == GFC_DEP_FORWARD) ?
+		    reverse[m] = (this_dep == GFC_DEP_FORWARD) ?
-			         GFC_FORWARD_SET : reverse[n];
+			         GFC_FORWARD_SET : reverse[m];
 
 		  /* Flag up overlap if dependence not compatible with
 		     the overall state of the expression.  */
-		  if (reverse && reverse[n] == GFC_REVERSE_SET
+		  if (reverse && reverse[m] == GFC_REVERSE_SET
 		        && this_dep == GFC_DEP_FORWARD)
 		    {
-	              reverse[n] = GFC_INHIBIT_REVERSE;
+	              reverse[m] = GFC_INHIBIT_REVERSE;
 		      this_dep = GFC_DEP_OVERLAP;
 		    }
-		  else if (reverse && reverse[n] == GFC_FORWARD_SET
+		  else if (reverse && reverse[m] == GFC_FORWARD_SET
 		        && this_dep == GFC_DEP_BACKWARD)
 		    {
-	              reverse[n] = GFC_INHIBIT_REVERSE;
+	              reverse[m] = GFC_INHIBIT_REVERSE;
 		      this_dep = GFC_DEP_OVERLAP;
 		    }
 
 		  /* If no intention of reversing or reversing is explicitly
 		     inhibited, convert backward dependence to overlap.  */
 		  if ((reverse == NULL && this_dep == GFC_DEP_BACKWARD)
-		      || (reverse != NULL && reverse[n] == GFC_INHIBIT_REVERSE))
+		      || (reverse != NULL && reverse[m] == GFC_INHIBIT_REVERSE))
 		    this_dep = GFC_DEP_OVERLAP;
 		}
 

gcc/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2014-07-12  Paul Thomas  <pault@gcc.gnu.org>
+
+	PR fortran/61780
+	* gfortran.dg/dependency_44.f90 : New test
+
 2014-07-12  Tobias Burnus  <burnus@net-b.de>
 
 	* gfortran.dg/coarray_atomic_1.f90: Update dg-error.

gcc/testsuite/gfortran.dg/dependency_44.f90

@@ -0,0 +1,36 @@
+! { dg-do run }
+! Tests fix for PR61780 in which the loop reversal mechanism was
+! not accounting for the first index being an element so that no
+! loop in this dimension is created.
+!
+! Contributed by Manfred Tietze on clf.
+!
+program prgm3
+    implicit none
+    integer, parameter :: n = 10, k = 3
+    integer :: i, j
+    integer, dimension(n,n) :: y
+    integer :: res1(n), res2(n)
+
+1   format(10i5)
+
+!initialize
+    do i=1,n
+        do j=1,n
+            y(i,j) = n*i + j
+        end do
+    end do
+    res2 = y(k,:)
+
+!shift right
+    y(k,4:n) = y(k,3:n-1)
+    y(k,3) = 0
+    res1 = y(k,:)
+    y(k,:) = res2
+    y(k,n:4:-1) = y(k,n-1:3:-1)
+    y(k,3) = 0
+    res2 = y(k,:)
+!    print *, res1
+!    print *, res2
+    if (any(res1 /= res2)) call abort ()
+end program prgm3