re PR middle-end/66867 (Suboptimal code generation for atomic_compare_exchange)

	PR middle-end/66867
	* builtins.c (expand_ifn_atomic_compare_exchange_into_call,
	expand_ifn_atomic_compare_exchange): New functions.
	* internal-fn.c (expand_ATOMIC_COMPARE_EXCHANGE): New function.
	* tree.h (build_call_expr_internal_loc): Rename to ...
	(build_call_expr_internal_loc_array): ... this.  Fix up type of
	last argument.
	* internal-fn.def (ATOMIC_COMPARE_EXCHANGE): New internal fn.
	* predict.c (expr_expected_value_1): Handle IMAGPART_EXPR of
	ATOMIC_COMPARE_EXCHANGE result.
	* builtins.h (expand_ifn_atomic_compare_exchange): New prototype.
	* gimple-fold.h (optimize_atomic_compare_exchange_p,
	fold_builtin_atomic_compare_exchange): New prototypes.
	* gimple-fold.c (optimize_atomic_compare_exchange_p,
	fold_builtin_atomic_compare_exchange): New functions..
	* tree-ssa.c (execute_update_addresses_taken): If
	optimize_atomic_compare_exchange_p, ignore &var in 2nd argument
	of call when finding addressable vars, and if such var becomes
	non-addressable, call fold_builtin_atomic_compare_exchange.

From-SVN: r237814

1 files changed, 25 insertions, 2 deletions

diff --git a/gcc/tree-ssa.c b/gcc/tree-ssa.c
index 247fa07..fd742f2 100644
--- a/gcc/tree-ssa.c
+++ b/gcc/tree-ssa.c
@@ -1414,8 +1414,21 @@ execute_update_addresses_taken (void)
 	  enum gimple_code code = gimple_code (stmt);
 	  tree decl;
 
-	  /* Note all addresses taken by the stmt.  */
-	  gimple_ior_addresses_taken (addresses_taken, stmt);
+	  if (code == GIMPLE_CALL
+	      && optimize_atomic_compare_exchange_p (stmt))
+	    {
+	      /* For __atomic_compare_exchange_N if the second argument
+		 is &var, don't mark var addressable;
+		 if it becomes non-addressable, we'll rewrite it into
+		 ATOMIC_COMPARE_EXCHANGE call.  */
+	      tree arg = gimple_call_arg (stmt, 1);
+	      gimple_call_set_arg (stmt, 1, null_pointer_node);
+	      gimple_ior_addresses_taken (addresses_taken, stmt);
+	      gimple_call_set_arg (stmt, 1, arg);
+	    }
+	  else
+	    /* Note all addresses taken by the stmt.  */
+	    gimple_ior_addresses_taken (addresses_taken, stmt);
 
 	  /* If we have a call or an assignment, see if the lhs contains
 	     a local decl that requires not to be a gimple register.  */
@@ -1657,6 +1670,16 @@ execute_update_addresses_taken (void)
 	    else if (gimple_code (stmt) == GIMPLE_CALL)
 	      {
 		unsigned i;
+		if (optimize_atomic_compare_exchange_p (stmt))
+		  {
+		    tree expected = gimple_call_arg (stmt, 1);
+		    if (bitmap_bit_p (suitable_for_renaming,
+				      DECL_UID (TREE_OPERAND (expected, 0))))
+		      {
+			fold_builtin_atomic_compare_exchange (&gsi);
+			continue;
+		      }
+		  }
 		for (i = 0; i < gimple_call_num_args (stmt); ++i)
 		  {
 		    tree *argp = gimple_call_arg_ptr (stmt, i);