[PATCH] Introduce warning -Womp-default-scope

["VandeVondele Joost" <joost dot vandevondele at mat dot ethz dot ch>]

Attached patch introduces an optional warning for an OMP parallel/task/teams construct without explicit default(none). This would effectively catch the number one reason of easy-to-avoid OMP bugs in our project.

Tested with check-fortran, full bootstrap & check in progress. OK for trunk if this passes ?

Joost

Index: gcc/testsuite/gfortran.dg/gomp/omp-default-scope.f90
===================================================================
--- gcc/testsuite/gfortran.dg/gomp/omp-default-scope.f90	(revision 0)
+++ gcc/testsuite/gfortran.dg/gomp/omp-default-scope.f90	(revision 0)
@@ -0,0 +1,11 @@
+! { dg-do compile }
+! { dg-options "-fopenmp -Womp-default-scope" }
+  SUBROUTINE S1(d)
+    IMPLICIT NONE
+    INTEGER :: i,d(*),c
+    !$OMP PARALLEL DO ! { dg-warning "construct without explicit" }
+    DO i=1,100
+       c= d(i)
+       d(i)=c*c
+    ENDDO
+  END SUBROUTINE S1
Index: gcc/gimplify.c
===================================================================
--- gcc/gimplify.c	(revision 215323)
+++ gcc/gimplify.c	(working copy)
@@ -6255,6 +6255,13 @@ gimplify_scan_omp_clauses (tree *list_p,
 	list_p = &OMP_CLAUSE_CHAIN (c);
     }
 
+  if (ctx->default_kind != OMP_CLAUSE_DEFAULT_NONE
+      && (ctx->region_type & ORT_PARALLEL
+          || ctx->region_type & ORT_TASK
+          || ctx->region_type == ORT_TEAMS))
+    warning_at (ctx->location, OPT_Womp_default_scope,
+      "OMP parallel/task/teams construct without explicit default(none)");
+
   gimplify_omp_ctxp = ctx;
 }
 
Index: gcc/common.opt
===================================================================
--- gcc/common.opt	(revision 215323)
+++ gcc/common.opt	(working copy)
@@ -591,6 +591,10 @@ Wodr
 Common Var(warn_odr_violations) Init(1) Warning
 Warn about some C++ One Definition Rule violations during link time optimization
 
+Womp-default-scope
+Common Var(warn_omp_default_scope) Warning
+Warn if an OMP parallel/task/teams construct has no explicit default(none) clause.
+
 Woverflow
 Common Var(warn_overflow) Init(1) Warning
 Warn about overflow in arithmetic expressions

Attachment: patch-warn-omp-default-scope_v01-CL.txt
Description: patch-warn-omp-default-scope_v01-CL.txt