* gengtype.c (write_field_root): Avoid out-of-scope access of newv.

	* tree-stdarg.c (execute_optimize_stdarg): Accept clobbers.

	* tree.h (TREE_CLOBBER_P): New macro.
	* gimple.h (gimple_clobber_p): New inline function.
	* gimplify.c (gimplify_bind_expr): Add clobbers for all variables
	that go out of scope and live in memory.
	* tree-ssa-operands.c (get_expr_operands): Transfer volatility also
	for constructors.
	* cfgexpand.c (decl_to_stack_part): New static variable.
	(add_stack_var): Allocate it, and remember mapping.
	(fini_vars_expansion): Deallocate it.
	(stack_var_conflict_p): Add early outs.
	(visit_op, visit_conflict, add_scope_conflicts_1,
	add_scope_conflicts): New static functions.
	(expand_used_vars_for_block): Don't call add_stack_var_conflict, tidy.
	(expand_used_vars): Add scope conflicts.
	(expand_gimple_stmt_1): Expand clobbers to nothing.
	(expand_debug_expr): Ditto.

	* tree-pretty-print.c (dump_generic_node): Dump clobbers nicely.
	* tree-ssa-live.c (remove_unused_locals): Remove clobbers that
	refer to otherwise unused locals.
	* tree-sra.c (build_accesses_from_assign): Ignore clobbers.
	* tree-ssa-dce.c (mark_stmt_if_obviously_necessary): Clobbers of
	SSA names aren't necessary.
	(propagate_necessity): Accept and ignore constructors on the rhs,
	tidy.
	* gimple.c (walk_gimple_op): Accept constructors like mem_rhs.
	* tree-ssa-structalias.c (find_func_aliases): Clobbers don't store
	any known value.
	* tree-ssa-sccvn.c (vn_reference_lookup_3): Ditto, in particular they
	don't zero-initialize something.
	* tree-ssa-phiopt.c (cond_if_else_store_replacement_1): Ignore
	clobber RHS, we don't want PHI nodes with those.

testsuite/
	* gcc.dg/tree-ssa/20031015-1.c: Adjust.
	* g++.dg/tree-ssa/ehcleanup-1.C: Ditto.
	* g++.dg/eh/builtin1.C: Rewrite to not use local variables.
	* g++.dg/eh/builtin2.C: Ditto.
	* g++.dg/eh/builtin3.C: Ditto.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@181172 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 42 insertions, 0 deletions

diff --git a/gcc/tree-ssa-live.c b/gcc/tree-ssa-live.c
index 65b3855775a..2a2c13393fe 100644
--- a/gcc/tree-ssa-live.c
+++ b/gcc/tree-ssa-live.c
@@ -688,6 +688,7 @@ remove_unused_locals (void)
   referenced_var_iterator rvi;
   bitmap global_unused_vars = NULL;
   unsigned srcidx, dstidx, num;
+  bool have_local_clobbers = false;
 
   /* Removing declarations from lexical blocks when not optimizing is
      not only a waste of time, it actually causes differences in stack
@@ -720,6 +721,12 @@ remove_unused_locals (void)
 	  if (is_gimple_debug (stmt))
 	    continue;
 
+	  if (gimple_clobber_p (stmt))
+	    {
+	      have_local_clobbers = true;
+	      continue;
+	    }
+
 	  if (b)
 	    TREE_USED (b) = true;
 
@@ -753,6 +760,41 @@ remove_unused_locals (void)
 	  TREE_USED (e->goto_block) = true;
     }
 
+  /* We do a two-pass approach about the out-of-scope clobbers.  We want
+     to remove them if they are the only references to a local variable,
+     but we want to retain them when there's any other.  So the first pass
+     ignores them, and the second pass (if there were any) tries to remove
+     them.  */
+  if (have_local_clobbers)
+    FOR_EACH_BB (bb)
+      {
+	gimple_stmt_iterator gsi;
+
+	for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi);)
+	  {
+	    gimple stmt = gsi_stmt (gsi);
+	    tree b = gimple_block (stmt);
+
+	    if (gimple_clobber_p (stmt))
+	      {
+		tree lhs = gimple_assign_lhs (stmt);
+		lhs = get_base_address (lhs);
+		if (TREE_CODE (lhs) == SSA_NAME)
+		  lhs = SSA_NAME_VAR (lhs);
+		if (DECL_P (lhs) && (!var_ann (lhs) || !is_used_p (lhs)))
+		  {
+		    unlink_stmt_vdef (stmt);
+		    gsi_remove (&gsi, true);
+		    release_defs (stmt);
+		    continue;
+		  }
+		if (b)
+		  TREE_USED (b) = true;
+	      }
+	    gsi_next (&gsi);
+	  }
+      }
+
   cfun->has_local_explicit_reg_vars = false;
 
   /* Remove unmarked local vars from local_decls.  */