Hi!
This is an attempt to avoid some further -Wreturn-type false positives,
by adding a langhook for block_may_fallthru and thus allowing it to handle
selected FE specific trees (like EXPR_STMT or THROW_EXPR) and handling also
TARGET_EXPR. Bootstrapped/regtested on x86_64-linux and i686-linux, ok for
trunk?
2012-11-20 Jakub Jelinek <ja...@redhat.com>
PR c++/54046
* Makefile.in (gimple-low.o): Depend on langhooks.h.
* gimple-low.c: Include langhooks.c.
(block_may_fallthru): Handle TARGET_EXPR and ERROR_MARK,
by default call lang_hooks.block_may_fallthru.
* langhooks.h (struct lang_hooks): Add block_may_fallthru
langhook.
* langhooks-def.h (LANG_HOOKS_BLOCK_MAY_FALLTHRU): Define.
(LANG_HOOKS_INITIALIZER): Use it.
* cp-objcp-common.h (LANG_HOOKS_BLOCK_MAY_FALLTHRU): Redefine.
* cp-objcp-common.c (cxx_block_may_fallthru): New function.
* cp-tree.h (cxx_block_may_fallthru): New prototype.
* g++.dg/warn/Wreturn-type-8.C: New test.
--- gcc/Makefile.in.jj 2012-11-20 11:36:51.000000000 +0100
+++ gcc/Makefile.in 2012-11-20 17:28:58.601741316 +0100
@@ -2519,7 +2519,7 @@ gimple-low.o : gimple-low.c $(CONFIG_H)
$(DIAGNOSTIC_CORE_H) $(GIMPLE_H) $(TREE_INLINE_H) langhooks.h \
$(LANGHOOKS_DEF_H) $(TREE_FLOW_H) $(TM_H) coretypes.h \
$(EXCEPT_H) $(FLAGS_H) $(RTL_H) $(FUNCTION_H) $(TREE_PASS_H) \
- $(HASHTAB_H) $(DIAGNOSTIC_CORE_H) tree-iterator.h
+ $(HASHTAB_H) $(DIAGNOSTIC_CORE_H) tree-iterator.h langhooks.h
omp-low.o : omp-low.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(TREE_H) \
$(RTL_H) $(GIMPLE_H) $(TREE_INLINE_H) langhooks.h $(DIAGNOSTIC_CORE_H) \
$(TREE_FLOW_H) $(FLAGS_H) $(EXPR_H) $(DIAGNOSTIC_CORE_H) \
--- gcc/gimple-low.c.jj 2012-11-19 14:41:18.000000000 +0100
+++ gcc/gimple-low.c 2012-11-20 17:28:33.518881995 +0100
@@ -32,6 +32,7 @@ along with GCC; see the file COPYING3.
#include "function.h"
#include "diagnostic-core.h"
#include "tree-pass.h"
+#include "langhooks.h"
/* The differences between High GIMPLE and Low GIMPLE are the
following:
@@ -739,8 +740,14 @@ block_may_fallthru (const_tree block)
case CLEANUP_POINT_EXPR:
return block_may_fallthru (TREE_OPERAND (stmt, 0));
- default:
+ case TARGET_EXPR:
+ return block_may_fallthru (TREE_OPERAND (stmt, 1));
+
+ case ERROR_MARK:
return true;
+
+ default:
+ return lang_hooks.block_may_fallthru (stmt);
}
}
--- gcc/langhooks.h.jj 2012-07-16 14:38:34.000000000 +0200
+++ gcc/langhooks.h 2012-11-20 17:25:07.019061084 +0100
@@ -1,6 +1,6 @@
/* The lang_hooks data structure.
Copyright 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010,
- 2011 Free Software Foundation, Inc.
+ 2011, 2012 Free Software Foundation, Inc.
This file is part of GCC.
@@ -456,6 +456,10 @@ struct lang_hooks
FUNCTION_DECL for `std::terminate'. */
tree (*eh_protect_cleanup_actions) (void);
+ /* Return true if a stmt can fallthru. Used by block_may_fallthru
+ to possibly handle language trees. */
+ bool (*block_may_fallthru) (const_tree);
+
/* True if this language uses __cxa_end_cleanup when the ARM EABI
is enabled. */
bool eh_use_cxa_end_cleanup;
--- gcc/langhooks-def.h.jj 2012-04-30 08:06:18.000000000 +0200
+++ gcc/langhooks-def.h 2012-11-20 17:26:15.616672118 +0100
@@ -115,6 +115,7 @@ extern void lhd_omp_firstprivatize_type_
#define LANG_HOOKS_EH_PERSONALITY lhd_gcc_personality
#define LANG_HOOKS_EH_RUNTIME_TYPE lhd_pass_through_t
#define LANG_HOOKS_EH_PROTECT_CLEANUP_ACTIONS NULL
+#define LANG_HOOKS_BLOCK_MAY_FALLTHRU hook_bool_const_tree_true
#define LANG_HOOKS_EH_USE_CXA_END_CLEANUP false
#define LANG_HOOKS_DEEP_UNSHARING false
@@ -300,6 +301,7 @@ extern void lhd_end_section (void);
LANG_HOOKS_EH_PERSONALITY, \
LANG_HOOKS_EH_RUNTIME_TYPE, \
LANG_HOOKS_EH_PROTECT_CLEANUP_ACTIONS, \
+ LANG_HOOKS_BLOCK_MAY_FALLTHRU, \
LANG_HOOKS_EH_USE_CXA_END_CLEANUP, \
LANG_HOOKS_DEEP_UNSHARING \
}
--- gcc/cp/cp-objcp-common.h.jj 2012-04-23 11:11:19.000000000 +0200
+++ gcc/cp/cp-objcp-common.h 2012-11-20 17:30:18.637283695 +0100
@@ -94,6 +94,8 @@ extern void cp_common_init_ts (void);
#define LANG_HOOKS_TYPE_HASH_EQ cxx_type_hash_eq
#undef LANG_HOOKS_MISSING_NORETURN_OK_P
#define LANG_HOOKS_MISSING_NORETURN_OK_P cp_missing_noreturn_ok_p
+#undef LANG_HOOKS_BLOCK_MAY_FALLTHRU
+#define LANG_HOOKS_BLOCK_MAY_FALLTHRU cxx_block_may_fallthru
/* Attribute hooks. */
#undef LANG_HOOKS_COMMON_ATTRIBUTE_TABLE
--- gcc/cp/cp-tree.h.jj 2012-11-19 14:41:16.000000000 +0100
+++ gcc/cp/cp-tree.h 2012-11-20 17:33:43.470104218 +0100
@@ -6019,6 +6019,7 @@ extern bool cp_var_mod_type_p (tree, t
extern void cxx_initialize_diagnostics (diagnostic_context *);
extern int cxx_types_compatible_p (tree, tree);
extern void init_shadowed_var_for_decl (void);
+extern bool cxx_block_may_fallthru (const_tree);
/* in cp-gimplify.c */
extern int cp_gimplify_expr (tree *, gimple_seq *,
--- gcc/cp/cp-objcp-common.c.jj 2012-05-17 08:40:35.000000000 +0200
+++ gcc/cp/cp-objcp-common.c 2012-11-20 17:40:40.147732468 +0100
@@ -227,6 +227,25 @@ init_shadowed_var_for_decl (void)
tree_decl_map_eq, 0);
}
+/* Return true if stmt can fall thru. Used by block_may_fallthru
+ default case. */
+
+bool
+cxx_block_may_fallthru (const_tree stmt)
+{
+ switch (TREE_CODE (stmt))
+ {
+ case EXPR_STMT:
+ return block_may_fallthru (EXPR_STMT_EXPR (stmt));
+
+ case THROW_EXPR:
+ return block_may_fallthru (TREE_OPERAND (stmt, 0));
+
+ default:
+ return true;
+ }
+}
+
void
cp_common_init_ts (void)
{
--- gcc/testsuite/g++.dg/warn/Wreturn-type-8.C.jj 2012-11-20
17:46:30.899731596 +0100
+++ gcc/testsuite/g++.dg/warn/Wreturn-type-8.C 2012-11-20 17:45:22.000000000
+0100
@@ -0,0 +1,90 @@
+// PR c++/54046
+// { dg-do compile }
+// { dg-options "-O0 -Wall" }
+
+void foo (void) __attribute__((noreturn));
+
+struct A
+{
+ ~A () {}
+};
+
+bool
+check1 (int x)
+{
+ A z;
+ switch (x)
+ {
+ case 0:
+ return false;
+ default:
+ throw "X";
+ break;
+ }
+}
+
+bool
+check2 (int x)
+{
+ A z;
+ switch (x)
+ {
+ case 0:
+ return false;
+ default:
+ foo ();
+ break;
+ }
+}
+
+bool
+check3 (int x)
+{
+ switch (x)
+ {
+ case 0:
+ return false;
+ default:
+ throw "X";
+ break;
+ }
+}
+
+bool
+check4 (int x)
+{
+ switch (x)
+ {
+ case 0:
+ return false;
+ default:
+ foo ();
+ break;
+ }
+}
+
+bool
+check5 (int x)
+{
+ A z;
+ switch (x)
+ {
+ case 0:
+ return false;
+ default:
+ throw "X";
+ }
+}
+
+bool
+check6 (int x)
+{
+ A z;
+ switch (x)
+ {
+ case 0:
+ return false;
+ default:
+ foo ();
+ }
+}
Jakub
