http://sourceware.org/ml/gdb-patches/2016-02/msg00842.html
Subject: [PATCH v2 4/6] fortran: enable parsing of stride parameter for subranges

From: Christoph Weinmann <christoph.t.weinmann@intel.com>

Allow the user to provide a stride parameter for Fortran
subarrays.  The stride parameter can be any integer except
'0'.  The default stride value is '1'.

2013-11-27  Christoph Weinmann  <christoph.t.weinmann@intel.com>

	* eval.c (value_f90_subarray): Add expression evaluation
	for a stride parameter in a Fortran range expression.
	* f-exp.y: Add yacc rules for writing info on the elt stack
	when the user provided a stride argument.
	* f-lang.h (F90_RANGE): Add field to enum to show when a
	stride was provided by the user.
	* parse.c (operator_length_standard): Check if a stride
	value was provided, and increment argument counter
	accordingly.


Signed-off-by: Christoph Weinmann <christoph.t.weinmann@intel.com>
---
 gdb/eval.c   | 10 +++++++++-
 gdb/f-exp.y  | 33 +++++++++++++++++++++++++++++++--
 gdb/f-lang.h |  5 +++--
 gdb/parse.c  |  3 +++
 4 files changed, 46 insertions(+), 5 deletions(-)

diff --git a/gdb/eval.c b/gdb/eval.c
index 9b8b051..308ada3 100644
--- a/gdb/eval.c
+++ b/gdb/eval.c
@@ -438,7 +438,7 @@ value_f90_subarray (struct value *array, struct expression *exp,
       struct subscript_range
       {
         enum f90_range_type f90_range_type;
-        LONGEST low, high;
+        LONGEST low, high, stride;
       }
       range;
       LONGEST number;
@@ -488,6 +488,14 @@ value_f90_subarray (struct value *array, struct expression *exp,
 	      == SUBARRAY_HIGH_BOUND)
 	    range->high = value_as_long (evaluate_subexp (NULL_TYPE, exp,
 							  pos, noside));
+
+	  /* Assign the user's stride value if provided.  */
+	  if ((range->f90_range_type & SUBARRAY_STRIDE) == SUBARRAY_STRIDE)
+	    range->stride = value_as_long (evaluate_subexp (NULL_TYPE, exp,
+							    pos, noside));
+	  /* Assign the default stride value '1'.  */
+	  else
+	    range->stride = 1;
 	}
       /* User input is an index.  E.g.: "p arry(5)".  */
       else
diff --git a/gdb/f-exp.y b/gdb/f-exp.y
index b1206de..5151fee 100644
--- a/gdb/f-exp.y
+++ b/gdb/f-exp.y
@@ -316,8 +316,8 @@ arglist	:	arglist ',' exp   %prec ABOVE_COMMA
 
 subrange:	exp ':' exp	%prec ABOVE_COMMA
 			{ write_exp_elt_opcode (pstate, OP_F90_RANGE);
-			  write_exp_elt_longcst (pstate,
-						 SUBARRAY_LOW_BOUND | SUBARRAY_HIGH_BOUND);
+			  write_exp_elt_longcst (pstate, SUBARRAY_LOW_BOUND
+						 | SUBARRAY_HIGH_BOUND);
 			  write_exp_elt_opcode (pstate, OP_F90_RANGE); }
 	;
 
@@ -339,6 +339,35 @@ subrange:	':'	%prec ABOVE_COMMA
 			  write_exp_elt_opcode (pstate, OP_F90_RANGE); }
 	;
 
+/* Each subrange type can have a stride argument.  */
+subrange:	exp ':' exp ':' exp %prec ABOVE_COMMA
+			{ write_exp_elt_opcode (pstate, OP_F90_RANGE);
+			  write_exp_elt_longcst (pstate, SUBARRAY_LOW_BOUND
+						 | SUBARRAY_HIGH_BOUND
+						 | SUBARRAY_STRIDE);
+			  write_exp_elt_opcode (pstate, OP_F90_RANGE); }
+	;
+
+subrange:	exp ':' ':' exp %prec ABOVE_COMMA
+			{ write_exp_elt_opcode (pstate, OP_F90_RANGE);
+			  write_exp_elt_longcst (pstate, SUBARRAY_LOW_BOUND
+						 | SUBARRAY_STRIDE);
+			  write_exp_elt_opcode (pstate, OP_F90_RANGE); }
+	;
+
+subrange:	':' exp ':' exp %prec ABOVE_COMMA
+			{ write_exp_elt_opcode (pstate, OP_F90_RANGE);
+			  write_exp_elt_longcst (pstate, SUBARRAY_HIGH_BOUND
+						 | SUBARRAY_STRIDE);
+			  write_exp_elt_opcode (pstate, OP_F90_RANGE); }
+	;
+
+subrange:	':' ':' exp %prec ABOVE_COMMA
+			{ write_exp_elt_opcode (pstate, OP_F90_RANGE);
+			  write_exp_elt_longcst (pstate, SUBARRAY_STRIDE);
+			  write_exp_elt_opcode (pstate, OP_F90_RANGE); }
+	;
+
 complexnum:     exp ',' exp 
                 	{ }                          
         ;
diff --git a/gdb/f-lang.h b/gdb/f-lang.h
index 4d56bf7..0ad57af 100644
--- a/gdb/f-lang.h
+++ b/gdb/f-lang.h
@@ -44,8 +44,9 @@ extern void f_val_print (struct type *, const gdb_byte *, int, CORE_ADDR,
    
 enum f90_range_type
   {
-    SUBARRAY_LOW_BOUND = 0x1,		/* "(low:)"  */
-    SUBARRAY_HIGH_BOUND = 0x2		/* "(:high)"  */
+    SUBARRAY_LOW_BOUND = 0x1,		/* "(low:)" or "(low::)" */
+    SUBARRAY_HIGH_BOUND = 0x2,		/* "(:high)" or "(:high:)"  */
+    SUBARRAY_STRIDE = 0x4		/* "(::stride)"  */
   };
 
 /* A common block.  */
diff --git a/gdb/parse.c b/gdb/parse.c
index d500279..07248c3 100644
--- a/gdb/parse.c
+++ b/gdb/parse.c
@@ -1018,6 +1018,9 @@ operator_length_standard (const struct expression *expr, int endpos,
       if ((range_type & SUBARRAY_HIGH_BOUND) == SUBARRAY_HIGH_BOUND)
 	args++;
 
+      if ((range_type & SUBARRAY_STRIDE) == SUBARRAY_STRIDE)
+	args++;
+
       break;
 
     default:
-- 
2.5.0