From 14fe7b530dc927a88169a841afc0cd806593dea8 Mon Sep 17 00:00:00 2001 From: Eli Zaretskii Date: Mon, 9 May 2011 05:59:23 -0400 Subject: Backport revisions 2011-04-24T05:30:24Z!eggert@cs.ucla.edu..2011-04-25T19:40:22Z!eggert@cs.ucla.edu (inclusive) from trunk (bug#8623) The next log entry shows the actual changes by Paul Eggert. Fix a problem with aliasing and vector headers. GCC 4.6.0 optimizes based on type-based alias analysis. For example, if b is of type struct buffer * and v of type struct Lisp_Vector *, then gcc -O2 was incorrectly assuming that &b->size != &v->size, and therefore "v->size = 1; b->size = 2; return v->size;" must therefore return 1. This assumption is incorrect for Emacs, since it type-puns struct Lisp_Vector * with many other types. To fix this problem, this patch adds a new type struct vector_header that documents the constraints on layout of vectors and pseudovectors, and helps optimizing compilers not get fooled by Emacs's type punning. It also adds the macros XSETTYPED_PVECTYPE XSETTYPED_PSEUDOVECTOR, TYPED_PSEUDOVECTORP, for similar reasons. src/lisp.h (XVECTOR_SIZE): New convenience macro. All previous uses of XVECTOR (foo)->size replaced to use this macro, to avoid the hassle of writing XVECTOR (foo)->header.size. src/lisp.h: Say "vectorlike header" rather than "vector header. (struct vectorlike_header): Rename from struct vector_header. (XVECTORLIKE_HEADER_SIZE): Renamed from XVECTOR_HEADER_SIZE. All uses changed. (XVECTOR_HEADER_SIZE): New macro, for use in XSETPSEUDOVECTOR. (XSETTYPED_PVECTYPE): New macro, specifying the name of the size member. (XSETPVECTYPE): Rewrite in terms of new macro. (XSETPVECTYPESIZE): New macro, specifying both type and size. This is a bit clearer, and further avoids the possibility of undesirable aliasing. (XSETTYPED_PSEUDOVECTOR): New macro, specifying the size. (XSETPSEUDOVECTOR): Rewrite in terms of XSETTYPED_PSEUDOVECTOR and XVECTOR_HEADER_SIZE. (XSETSUBR): Rewrite in terms of XSETTYPED_PSEUDOVECTOR and XSIZE, since Lisp_Subr is a special case (no "next" field). (ASIZE): Rewrite in terms of XVECTOR_SIZE. (struct vector_header): New type. (TYPED_PSEUDOVECTORP): New macro, also specifying the C type of the object, to help avoid aliasing. (PSEUDOVECTORP): Rewrite in terms of TYPED_PSEUDOVECTORP. (SUBRP): Likewise, since Lisp_Subr is a special case. src/lisp.h (struct Lisp_Vector, struct Lisp_Char_Table): (struct Lisp_Sub_Char_Table, struct Lisp_Bool_Vector): (struct Lisp_Hash_Table): Combine first two members into a single struct vector_header member. All uses of "size" and "next" members changed to be "header.size" and "header.next". src/buffer.h (struct buffer): Likewise. src/font.h (struct font_spec, struct font_entity, struct font): Likewise. src/frame.h (struct frame): Likewise. src/process.h (struct Lisp_Process): Likewise. src/termhooks.h (struct terminal): Likewise. src/window.c (struct save_window_data, struct saved_window): Likewise. src/window.h (struct window): Likewise. src/alloc.c (allocate_buffer, Fmake_bool_vector, allocate_pseudovector): Use XSETPVECTYPESIZE, not XSETPVECTYPE, to avoid aliasing problems. src/buffer.c (init_buffer_once): Likewise. src/lread.c (defsubr): Use XSETTYPED_PVECTYPE, since Lisp_Subr is a special case. src/process.c (Fformat_network_address): Use local var for size, for brevity. src/fns.c (vector): Remove; this old hack is no longer needed. src/bytecode.c (exec_byte_code): Don't use XVECTOR before CHECK_VECTOR. --- src/xmenu.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) (limited to 'src/xmenu.c') diff --git a/src/xmenu.c b/src/xmenu.c index c2e70e13bf9..2a05c52ee34 100644 --- a/src/xmenu.c +++ b/src/xmenu.c @@ -1012,6 +1012,7 @@ set_frame_menubar (f, first_time, deep_p) Lisp_Object *previous_items = (Lisp_Object *) alloca (previous_menu_items_used * sizeof (Lisp_Object)); + EMACS_UINT subitems; /* If we are making a new widget, its contents are empty, do always reinitialize them. */ @@ -1056,13 +1057,14 @@ set_frame_menubar (f, first_time, deep_p) menu_items = f->menu_bar_vector; menu_items_allocated = VECTORP (menu_items) ? ASIZE (menu_items) : 0; - submenu_start = (int *) alloca (XVECTOR (items)->size * sizeof (int *)); - submenu_end = (int *) alloca (XVECTOR (items)->size * sizeof (int *)); - submenu_n_panes = (int *) alloca (XVECTOR (items)->size * sizeof (int)); + subitems = XVECTOR_SIZE (items) / 4; + submenu_start = (int *) alloca (subitems * sizeof (int *)); + submenu_end = (int *) alloca (subitems * sizeof (int *)); + submenu_n_panes = (int *) alloca (subitems * sizeof (int)); submenu_top_level_items - = (int *) alloca (XVECTOR (items)->size * sizeof (int *)); + = (int *) alloca (subitems * sizeof (int *)); init_menu_items (); - for (i = 0; i < XVECTOR (items)->size; i += 4) + for (i = 0; i < subitems; i += 4) { Lisp_Object key, string, maps; @@ -1142,7 +1144,7 @@ set_frame_menubar (f, first_time, deep_p) /* Now GC cannot happen during the lifetime of the widget_value, so it's safe to store data from a Lisp_String. */ wv = first_wv->contents; - for (i = 0; i < XVECTOR (items)->size; i += 4) + for (i = 0; i < XVECTOR_SIZE (items); i += 4) { Lisp_Object string; string = XVECTOR (items)->contents[i + 1]; @@ -1168,7 +1170,7 @@ set_frame_menubar (f, first_time, deep_p) first_wv = wv; items = FRAME_MENU_BAR_ITEMS (f); - for (i = 0; i < XVECTOR (items)->size; i += 4) + for (i = 0; i < XVECTOR_SIZE (items); i += 4) { Lisp_Object string; -- cgit v1.2.1