Attachment 45900 Details for Bug 20408 – fix

[patch] fix

20408.patch (text/plain), 3.88 KB, created by Jason Merrill on 2019-03-05 22:47:33 UTC

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Creator: Jason Merrill

Created: 2019-03-05 22:47:33 UTC

Size: 3.88 KB

patch

obsolete

>commit cc11073f74626fa0f33b8e1a67a72b3c37ef284d
>Author: Jason Merrill <jason@redhat.com>
>Date:   Sat Mar 2 01:07:41 2019 -0500
>
>            PR c++/86485 - -Wmaybe-unused with empty class ?:
>    
>            * cp-gimplify.c (simple_empty_class_p): Also true for MODIFY_EXPR.
>
>diff --git a/gcc/cp/cp-gimplify.c b/gcc/cp/cp-gimplify.c
>index 12c576ca3fd..2d892ca1264 100644
>--- a/gcc/cp/cp-gimplify.c
>+++ b/gcc/cp/cp-gimplify.c
>@@ -571,19 +571,20 @@ gimplify_must_not_throw_expr (tree *expr_p, gimple_seq *pre_p)
>    return slot optimization alone because it isn't a copy.  */
> 
> static bool
>-simple_empty_class_p (tree type, tree op)
>+simple_empty_class_p (tree type, tree op, tree_code code)
> {
>   return
>     ((TREE_CODE (op) == COMPOUND_EXPR
>-      && simple_empty_class_p (type, TREE_OPERAND (op, 1)))
>+      && simple_empty_class_p (type, TREE_OPERAND (op, 1), code))
>      || TREE_CODE (op) == EMPTY_CLASS_EXPR
>+     || code == MODIFY_EXPR
>      || is_gimple_lvalue (op)
>      || INDIRECT_REF_P (op)
>      || (TREE_CODE (op) == CONSTRUCTOR
>-	 && CONSTRUCTOR_NELTS (op) == 0
>-	 && !TREE_CLOBBER_P (op))
>+	 && CONSTRUCTOR_NELTS (op) == 0)
>      || (TREE_CODE (op) == CALL_EXPR
> 	 && !CALL_EXPR_RETURN_SLOT_OPT (op)))
>+    && !TREE_CLOBBER_P (op)
>     && is_really_empty_class (type, /*ignore_vptr*/true);
> }
> 
>@@ -692,7 +693,7 @@ cp_gimplify_expr (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p)
> 	  TREE_OPERAND (*expr_p, 1) = build1 (VIEW_CONVERT_EXPR,
> 					      TREE_TYPE (op0), op1);
> 
>-	else if (simple_empty_class_p (TREE_TYPE (op0), op1))
>+	else if (simple_empty_class_p (TREE_TYPE (op0), op1, code))
> 	  {
> 	    /* Remove any copies of empty classes.  Also drop volatile
> 	       variables on the RHS to avoid infinite recursion from
>
>commit c84e0e7af74e018aab19e4d0ea5e9f2653934442
>Author: Jason Merrill <jason@redhat.com>
>Date:   Mon Mar 4 17:33:59 2019 -0500
>
>            PR c++/20408 - unnecessary code for empty struct.
>    
>            * call.c (build_call_a): Use simple_empty_class_p.
>
>diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
>index d5b0560a897..57109f5df33 100644
>--- a/gcc/cp/cp-tree.h
>+++ b/gcc/cp/cp-tree.h
>@@ -7589,6 +7589,7 @@ extern tree cp_fully_fold_init			(tree);
> extern void clear_fold_cache			(void);
> extern tree lookup_hotness_attribute		(tree);
> extern tree process_stmt_hotness_attribute	(tree, location_t);
>+extern bool simple_empty_class_p		(tree, tree, tree_code);
> 
> /* in name-lookup.c */
> extern tree strip_using_decl                    (tree);
>diff --git a/gcc/cp/call.c b/gcc/cp/call.c
>index 16676664760..1bd199c53b7 100644
>--- a/gcc/cp/call.c
>+++ b/gcc/cp/call.c
>@@ -394,7 +394,7 @@ build_call_a (tree function, int n, tree *argarray)
>       {
> 	tree arg = CALL_EXPR_ARG (function, i);
> 	if (is_empty_class (TREE_TYPE (arg))
>-	    && ! TREE_ADDRESSABLE (TREE_TYPE (arg)))
>+	    && simple_empty_class_p (TREE_TYPE (arg), arg, INIT_EXPR))
> 	  {
> 	    tree t = build0 (EMPTY_CLASS_EXPR, TREE_TYPE (arg));
> 	    arg = build2 (COMPOUND_EXPR, TREE_TYPE (t), arg, t);
>diff --git a/gcc/cp/cp-gimplify.c b/gcc/cp/cp-gimplify.c
>index 2d892ca1264..8eecbf3fb19 100644
>--- a/gcc/cp/cp-gimplify.c
>+++ b/gcc/cp/cp-gimplify.c
>@@ -570,7 +570,7 @@ gimplify_must_not_throw_expr (tree *expr_p, gimple_seq *pre_p)
>    non-empty CONSTRUCTORs get reduced properly, and we leave the
>    return slot optimization alone because it isn't a copy.  */
> 
>-static bool
>+bool
> simple_empty_class_p (tree type, tree op, tree_code code)
> {
>   return
>diff --git a/gcc/testsuite/g++.dg/tree-ssa/empty-3.C b/gcc/testsuite/g++.dg/tree-ssa/empty-3.C
>new file mode 100644
>index 00000000000..f340bd4070b
>--- /dev/null
>+++ b/gcc/testsuite/g++.dg/tree-ssa/empty-3.C
>@@ -0,0 +1,16 @@
>+// PR c++/20408
>+// { dg-additional-options -fdump-tree-gimple }
>+// { dg-final { scan-tree-dump-times "struct Foo" 2 "gimple" } }
>+
>+struct Foo {};
>+void foo(const Foo&);
>+void bar(Foo);
>+
>+void fooc(void)
>+{
>+        foo(Foo());
>+}
>+void barc(void)
>+{
>+        bar(Foo());
>+}

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Attachments on bug 20408: 45900