re PR fortran/49103 (local variables exchange values / wrong code with -O3)

	PR fortran/49103
	* tree.h (DECL_NONSHAREABLE): Define.
	(struct tree_decl_common): Change decl_common_unused to
	decl_nonshareable_flag.
	* cfgexpand.c (expand_used_vars_for_block, clear_tree_used):
	Ignore vars with DECL_NONSHAREABLE bit set.
	* tree-cfg.c (gimple_duplicate_bb): Set DECL_NONSHAREABLE
	on stores to automatic aggregate vars.

	* gfortran.dg/pr49103.f90: New test.

From-SVN: r175028

1 files changed, 7 insertions, 2 deletions

diff --git a/gcc/tree.h b/gcc/tree.h
index 30c77d8..f55574d 100644
--- a/gcc/tree.h
+++ b/gcc/tree.h
@@ -1398,6 +1398,10 @@ extern void omp_clause_range_check_failed (const_tree, const char *, int,
 #define DECL_READ_P(NODE) \
   (TREE_CHECK2 (NODE, VAR_DECL, PARM_DECL)->decl_common.decl_read_flag)
 
+#define DECL_NONSHAREABLE(NODE) \
+  (TREE_CHECK2 (NODE, VAR_DECL, \
+		RESULT_DECL)->decl_common.decl_nonshareable_flag)
+
 /* In a CALL_EXPR, means that the call is the jump from a thunk to the
    thunked-to function.  */
 #define CALL_FROM_THUNK_P(NODE) (CALL_EXPR_CHECK (NODE)->base.protected_flag)
@@ -2887,8 +2891,9 @@ struct GTY(()) tree_decl_common {
      being set.  */
   unsigned decl_read_flag : 1;
 
-  /* Padding so that 'off_align' can be on a 32-bit boundary.  */
-  unsigned decl_common_unused : 1;
+  /* In VAR_DECL or RESULT_DECL set when significant code movement precludes
+     attempting to share the stack slot with some other variable.  */
+  unsigned decl_nonshareable_flag : 1;
 
   /* DECL_OFFSET_ALIGN, used only for FIELD_DECLs.  */
   unsigned int off_align : 8;