[patch, fortran] Fix PR 50690

[Thomas Koenig <tkoenig at netcologne dot de>]

Hello world,

this is what I hope is the final round of the OMP front-end optimization
patch.  This one ignores outer workshares when doing function
elimination within omp do and similar blocks.

Regression-tested.  OK for trunk?

	Thomas


2011-12-02  Thomas Koenig  <tkoenig@gcc.gnu.org>

        PR fortran/50690
        * frontend-passes.c (omp_level):  New variable.
        (omp_size):  New variable.
        (omp_block):  New variable.
        (gfc_run_passes):  Allocate and deallocate omp_block, set
        omp_size.
        (cfe_expr_0):  Don't eliminiate common function if it would put
        the variable immediately into a WORKSHARE construct.
        (optimize_namespace):  Set omp_level.
        (gfc_code_walker):  Keep track of OMP PARALLEL and OMP WORKSHARE
        constructs.

2011-12-02  Thomas Koenig  <tkoenig@gcc.gnu.org>

        PR fortran/50690
        * gfortran.dg/gomp/workshare2.f90:  New test.
        * gfortran.dg/gomp/workshare3.f90:  New test.

Index: frontend-passes.c
===================================================================
--- frontend-passes.c	(Revision 181809)
+++ frontend-passes.c	(Arbeitskopie)
@@ -66,6 +66,13 @@ static gfc_namespace *current_ns;
 
 static int forall_level;
 
+/* Keep track of the OMP blocks, so we can mark variables introduced
+   by optimizations as private.  */
+
+static int omp_level;
+static int omp_size;
+static gfc_code **omp_block;
+
 /* Entry point - run all passes for a namespace.  So far, only an
    optimization pass is run.  */
 
@@ -76,12 +83,15 @@ gfc_run_passes (gfc_namespace *ns)
     {
       expr_size = 20;
       expr_array = XNEWVEC(gfc_expr **, expr_size);
+      omp_size = 20;
+      omp_block = XCNEWVEC(gfc_code *, omp_size);
 
       optimize_namespace (ns);
       if (gfc_option.dump_fortran_optimized)
 	gfc_dump_parse_tree (ns, stdout);
 
       XDELETEVEC (expr_array);
+      XDELETEVEC (omp_block);
     }
 }
 
@@ -367,6 +377,23 @@ cfe_expr_0 (gfc_expr **e, int *walk_subtrees,
   int i,j;
   gfc_expr *newvar;
 
+  /* If we are within an OMP WORKSHARE or OMP PARALLEL WORKSHARE
+     construct, don't do this optimization.  Only look at the
+     innermost level because an EXEC_OMP_PARALLEL{,_DO,_SECTIONS}
+     nested in an EXEC_OMP_WORKSHARE/EXEC_OMP_PARALLEL_WORKSHARE
+     is OK.  */
+  if (omp_level > 0)
+    {
+      gfc_exec_op op;
+      op = omp_block[omp_level - 1]->op;
+
+      if (op == EXEC_OMP_WORKSHARE || op == EXEC_OMP_PARALLEL_WORKSHARE)
+	{
+	  *walk_subtrees = 0;
+	  return 0;
+	}
+    }
+
   expr_count = 0;
 
   gfc_expr_walker (e, cfe_register_funcs, NULL);
@@ -505,6 +532,7 @@ optimize_namespace (gfc_namespace *ns)
 
   current_ns = ns;
   forall_level = 0;
+  omp_level = 0;
 
   gfc_code_walker (&ns->code, convert_do_while, dummy_expr_callback, NULL);
   gfc_code_walker (&ns->code, cfe_code, cfe_expr_0, NULL);
@@ -1150,11 +1178,13 @@ gfc_code_walker (gfc_code **c, walk_code_fn_t code
 	  gfc_actual_arglist *a;
 	  gfc_code *co;
 	  gfc_association_list *alist;
+	  bool in_omp;
 
 	  /* There might be statement insertions before the current code,
 	     which must not affect the expression walker.  */
 
 	  co = *c;
+	  in_omp = false;
 
 	  switch (co->op)
 	    {
@@ -1330,14 +1360,32 @@ gfc_code_walker (gfc_code **c, walk_code_fn_t code
 	      WALK_SUBEXPR (co->ext.dt->extra_comma);
 	      break;
 
-	    case EXEC_OMP_DO:
 	    case EXEC_OMP_PARALLEL:
 	    case EXEC_OMP_PARALLEL_DO:
 	    case EXEC_OMP_PARALLEL_SECTIONS:
 	    case EXEC_OMP_PARALLEL_WORKSHARE:
+	    case EXEC_OMP_WORKSHARE:
+
+	      /* Register all OMP PARALLEL and WORKSHARE constructs
+		 on a stack so they can be handled separately for
+		 common function elimination.  */
+
+	      in_omp = 1;
+
+	      if (omp_level >= omp_size)
+		{
+		  omp_size += omp_size;
+		  omp_block = XRESIZEVEC(gfc_code *, omp_block, omp_size);
+		}
+
+	      omp_block[omp_level] = co;
+	      omp_level ++;
+
+	      /* Fall through. */
+
 	    case EXEC_OMP_SECTIONS:
+	    case EXEC_OMP_DO:
 	    case EXEC_OMP_SINGLE:
-	    case EXEC_OMP_WORKSHARE:
 	    case EXEC_OMP_END_SINGLE:
 	    case EXEC_OMP_TASK:
 	      if (co->ext.omp_clauses)
@@ -1366,6 +1414,9 @@ gfc_code_walker (gfc_code **c, walk_code_fn_t code
 	  if (co->op == EXEC_FORALL)
 	    forall_level --;
 
+	  if (in_omp)
+	    omp_level --;
+
 	}
     }
   return 0;

Attachment: workshare3.f90
Description: Text document

Attachment: workshare2.f90
Description: Text document