2007-08-26 Asher Langton <langton2@llnl.gov>

	    Tobias Burnus  <burnus@net-b.de>

        * gfortran.h (gfc_option_t): Add flag_recursive.
	* lang.opt: Add -frecursive option and update -fopenmp.
	* invoke.texi (-frecursive): Document new option.
	(-fopenmp,-fno-automatic,-fmax-stack-var-size): Update.
	* options.c (gfc_init_options, gfc_post_options,
	gfc_handle_option): Add -frecursive and modify -fopenmp.
	(gfc_post_options): Add warning for conflicting flags.

2007-08-26  Asher Langton  <langton2@llnl.gov>

	* gfortran.dg/recursive_stack.f90: New.
	* gfortran.dg/openmp_stack.f90: New.



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@127813 138bc75d-0d04-0410-961f-82ee72b054a4

5 files changed, 77 insertions, 9 deletions

diff --git a/gcc/fortran/ChangeLog b/gcc/fortran/ChangeLog
index 81d7bddd56d..903b713054b 100644
--- a/gcc/fortran/ChangeLog
+++ b/gcc/fortran/ChangeLog
@@ -1,3 +1,14 @@
+2007-08-26  Asher Langton  <langton2@llnl.gov>
+	    Tobias Burnus  <burnus@net-b.de>
+
+	* gfortran.h (gfc_option_t): Add flag_recursive.
+	* lang.opt: Add -frecursive option and update -fopenmp.
+	* invoke.texi (-frecursive): Document new option.
+	(-fopenmp,-fno-automatic,-fmax-stack-var-size): Update.
+	* options.c (gfc_init_options, gfc_post_options,
+	gfc_handle_option): Add -frecursive and modify -fopenmp.
+	(gfc_post_options): Add warning for conflicting flags.
+
 2007-08-26  Tobias Burnus  <burnus@net-b.de>
 
 	PR fortran/31298
diff --git a/gcc/fortran/gfortran.h b/gcc/fortran/gfortran.h
index 11d7adce8f7..383270e603a 100644
--- a/gcc/fortran/gfortran.h
+++ b/gcc/fortran/gfortran.h
@@ -1863,6 +1863,7 @@ typedef struct
   int flag_openmp;
   int flag_sign_zero;
   int flag_module_private;
+  int flag_recursive;
 
   int fpe;
 
diff --git a/gcc/fortran/invoke.texi b/gcc/fortran/invoke.texi
index c68a2613960..e58cb8cbee7 100644
--- a/gcc/fortran/invoke.texi
+++ b/gcc/fortran/invoke.texi
@@ -156,7 +156,7 @@ and warnings}.
 -fsecond-underscore @gol
 -fbounds-check  -fmax-stack-var-size=@var{n} @gol
 -fpack-derived  -frepack-arrays  -fshort-enums  -fexternal-blas @gol
--fblas-matmul-limit=@var{n}}
+-fblas-matmul-limit=@var{n} -frecursive}
 @end table
 
 @menu
@@ -296,7 +296,7 @@ and @code{c$omp}, @code{*$omp} and @code{!$omp} directives in fixed form,
 @code{!$} conditional compilation sentinels in free form
 and @code{c$}, @code{*$} and @code{!$} sentinels in fixed form, 
 and when linking arranges for the OpenMP runtime library to be linked
-in.
+in.  The option @option{-fopenmp} implies @option{-frecursive}.
 
 @item -frange-check
 @opindex @code{frange-check}
@@ -710,10 +710,13 @@ it.
 @opindex @code{fno-automatic}
 @cindex @code{SAVE} statement
 @cindex statement, @code{SAVE}
-Treat each program unit as if the @code{SAVE} statement was specified for
-every local variable and array referenced in it. Does not affect common
-blocks. (Some Fortran compilers provide this option under the name
-@option{-static}.)
+Treat each program unit (except those marked as RECURSIVE) as if the
+@code{SAVE} statement were specified for every local variable and array
+referenced in it. Does not affect common blocks. (Some Fortran compilers
+provide this option under the name @option{-static} or @option{-save}.)
+The default, which is @option{-fautomatic}, uses the stack for local
+variables smaller than the value given by @option{-fmax-stack-var-size}.
+Use the option @option{-frecursive} to use no static memory. 
 
 @item -ff2c
 @opindex ff2c
@@ -865,7 +868,10 @@ substring references.
 @item -fmax-stack-var-size=@var{n}
 @opindex @code{fmax-stack-var-size}
 This option specifies the size in bytes of the largest array that will be put
-on the stack.
+on the stack; if the size is exceeded static memory is used (except in
+procedures marked as RECURSIVE). Use the option @option{-frecursive} to
+allow for recursive procedures which do not have a RECURSIVE attribute or
+for parallel programs. Use @option{-fno-automatic} to never use the stack.
 
 This option currently only affects local arrays declared with constant
 bounds, and may not apply to all character variables.
@@ -919,6 +925,12 @@ geometric mean of the dimensions of the argument and result matrices.
 
 The default value for @var{n} is 30.
 
+@item -frecursive
+@opindex @code{frecursive}
+Allow indirect recursion by forcing all local arrays to be allocated
+on the stack. This flag cannot be used together with
+@option{-fmax-stack-var-size=} or @option{-fno-automatic}.
+
 @end table
 
 @xref{Code Gen Options,,Options for Code Generation Conventions,
diff --git a/gcc/fortran/lang.opt b/gcc/fortran/lang.opt
index 3072051a1f4..558cf657aac 100644
--- a/gcc/fortran/lang.opt
+++ b/gcc/fortran/lang.opt
@@ -218,7 +218,7 @@ Set default accessibility of module entities to PRIVATE.
 
 fopenmp
 Fortran
-Enable OpenMP
+Enable OpenMP (also sets frecursive)
 
 fpack-derived
 Fortran
@@ -240,6 +240,10 @@ frecord-marker=8
 Fortran RejectNegative
 Use an 8-byte record marker for unformatted files
 
+frecursive
+Fortran
+Allocate local variables on the stack to allow indirect recursion
+
 frepack-arrays
 Fortran
 Copy array sections into a contiguous block on procedure entry
diff --git a/gcc/fortran/options.c b/gcc/fortran/options.c
index 0bea67d7eea..3ab736236be 100644
--- a/gcc/fortran/options.c
+++ b/gcc/fortran/options.c
@@ -86,7 +86,10 @@ gfc_init_options (unsigned int argc ATTRIBUTE_UNUSED,
   gfc_option.flag_f2c = 0;
   gfc_option.flag_second_underscore = -1;
   gfc_option.flag_implicit_none = 0;
-  gfc_option.flag_max_stack_var_size = 32768;
+
+  /* Default value of flag_max_stack_var_size is set in gfc_post_options.  */
+  gfc_option.flag_max_stack_var_size = -2;
+
   gfc_option.flag_range_check = 1;
   gfc_option.flag_pack_derived = 0;
   gfc_option.flag_repack_arrays = 0;
@@ -103,6 +106,7 @@ gfc_init_options (unsigned int argc ATTRIBUTE_UNUSED,
   gfc_option.flag_d_lines = -1;
   gfc_option.flag_openmp = 0;
   gfc_option.flag_sign_zero = 1;
+  gfc_option.flag_recursive = 0;
 
   gfc_option.fpe = 0;
 
@@ -290,6 +294,37 @@ gfc_post_options (const char **pfilename)
   if (gfc_option.flag_second_underscore == -1)
     gfc_option.flag_second_underscore = gfc_option.flag_f2c;
 
+  if (!gfc_option.flag_automatic && gfc_option.flag_max_stack_var_size != -2
+      && gfc_option.flag_max_stack_var_size != 0)
+    gfc_warning_now ("Flag -fno-automatic overwrites -fmax-stack-var-size=%d",
+		     gfc_option.flag_max_stack_var_size);
+  else if (!gfc_option.flag_automatic && gfc_option.flag_recursive)
+    gfc_warning_now ("Flag -fno-automatic overwrites -frecursive");
+  else if (!gfc_option.flag_automatic && gfc_option.flag_openmp)
+    gfc_warning_now ("Flag -fno-automatic overwrites -frecursive implied by "
+		     "-fopenmp");
+  else if (gfc_option.flag_max_stack_var_size != -2
+	   && gfc_option.flag_recursive)
+    gfc_warning_now ("Flag -frecursive overwrites -fmax-stack-var-size=%d",
+		     gfc_option.flag_max_stack_var_size);
+  else if (gfc_option.flag_max_stack_var_size != -2
+	   && gfc_option.flag_openmp)
+    gfc_warning_now ("Flag -fmax-stack-var-size=%d overwrites -frecursive "
+		     "implied by -fopenmp", 
+		     gfc_option.flag_max_stack_var_size);
+
+  /* Implied -frecursive; implemented as -fmax-stack-var-size=-1.  */
+  if (gfc_option.flag_max_stack_var_size == -2 && gfc_option.flag_openmp)
+    gfc_option.flag_max_stack_var_size = -1;
+
+  /* Set default.  */
+  if (gfc_option.flag_max_stack_var_size == -2)
+    gfc_option.flag_max_stack_var_size = 32768;
+
+  /* Implement -frecursive as -fmax-stack-var-size=-1.  */
+  if (gfc_option.flag_recursive)
+    gfc_option.flag_max_stack_var_size = -1;
+
   /* Implement -fno-automatic as -fmax-stack-var-size=0.  */
   if (!gfc_option.flag_automatic)
     gfc_option.flag_max_stack_var_size = 0;
@@ -698,6 +733,11 @@ gfc_handle_option (size_t scode, const char *arg, int value)
 			 MAX_SUBRECORD_LENGTH);
 
       gfc_option.max_subrecord_length = value;
+      break;
+
+    case OPT_frecursive:
+      gfc_option.flag_recursive = 1;
+      break;
     }
 
   return result;