[rfa] ENUM_BITFIELD, here it comes again

Michael Elizabeth Chastain
2003-08-20T02:50:23Z

Here we go again ... a new version of my ENUM_BITFIELD patch.

First the good part:

before: 99360768
after: 90001408

This is a medium sized program (a specific build of gdb) along with a
debugging version of glibc using "gdb -readnow HEAD-gdb-old". Then I
typed 'maint space 1'.

The major difference from the previous version is that I hoisted the
definition of 'enum minimal_symbol_type' from inside 'struct
minimal_symbol' to the top level. This avoids trouble with gcc
warnings (gcc 3.3.1) or errors (gcc 3.2-7-rh).

Testing: as before, I ran the test suite with gcc v2 and v3,
dwarf-2 and stabs+, binutils 2.14. Also, I tested the non-gcc case
by putting an "#if 0" into the defs.h test in order to get the
non-gcc path.

Size reduction (on my vanilla native i686-pc-linux-gnu):

struct general_symbol_info 24 20
struct minimal_symbol 44 40
struct symbol 60 48
struct partial_symbol 32 24

Jim B approved an earlier version of this patch, but then I noticed
that little enum glitch. Sigh.

Okay to commit?

Michael C

===

2003-08-19 Michael Chastain <mec@shout.net>

* defs.h (ENUM_BITFIELD): New macro.
* symtab.h (ENUM_BITFIELD): Use it.
(BYTE_BITFIELD): Remove old macro, which was already disabled.

Index: defs.h
===================================================================
RCS file: /cvs/src/src/gdb/defs.h,v
retrieving revision 1.127
diff -u -r1.127 defs.h
--- defs.h 9 Aug 2003 14:57:30 -0000 1.127
+++ defs.h 19 Aug 2003 18:34:31 -0000
@@ -285,6 +285,15 @@
#endif
#endif

+/* Be conservative and use enum bitfields only with GCC.
+ This is copied from gcc 3.3.1, system.h. */
+
+#if defined(__GNUC__) && (__GNUC__ >= 2)
+#define ENUM_BITFIELD(TYPE) enum TYPE
+#else
+#define ENUM_BITFIELD(TYPE) unsigned int
+#endif
+
/* Needed for various prototypes */

struct symtab;
Index: symtab.h
===================================================================
RCS file: /cvs/src/src/gdb/symtab.h,v
retrieving revision 1.77
diff -u -r1.77 symtab.h
--- symtab.h 22 Jul 2003 15:41:59 -0000 1.77
+++ symtab.h 19 Aug 2003 18:34:33 -0000
@@ -35,17 +35,6 @@
struct axs_value;
struct agent_expr;

-/* Don't do this; it means that if some .o's are compiled with GNU C
- and some are not (easy to do accidentally the way we configure
- things; also it is a pain to have to "make clean" every time you
- want to switch compilers), then GDB dies a horrible death. */
-/* GNU C supports enums that are bitfields. Some compilers don't. */
-#if 0 && defined(__GNUC__) && !defined(BYTE_BITFIELD)
-#define BYTE_BITFIELD :8;
-#else
-#define BYTE_BITFIELD /*nothing */
-#endif
-
/* Define a structure for the information that is common to all symbol types,
including minimal symbols, partial symbols, and full symbols. In a
multilanguage environment, some language specific information may need to
@@ -107,7 +96,7 @@
This is used to select one of the fields from the language specific
union above. */

- enum language language BYTE_BITFIELD;
+ ENUM_BITFIELD(language) language : 8;

/* Which section is this symbol in? This is an index into
section_offsets for this objfile. Negative means that the symbol
@@ -227,6 +216,37 @@
#define SYMBOL_MATCHES_NATURAL_NAME(symbol, name) \
(strcmp_iw (SYMBOL_NATURAL_NAME (symbol), (name)) == 0)

+/* Classification types for this symbol. These should be taken as "advisory
+ only", since if gdb can't easily figure out a classification it simply
+ selects mst_unknown. It may also have to guess when it can't figure out
+ which is a better match between two types (mst_data versus mst_bss) for
+ example. Since the minimal symbol info is sometimes derived from the
+ BFD library's view of a file, we need to live with what information bfd
+ supplies. */
+
+enum minimal_symbol_type
+{
+ mst_unknown = 0, /* Unknown type, the default */
+ mst_text, /* Generally executable instructions */
+ mst_data, /* Generally initialized data */
+ mst_bss, /* Generally uninitialized data */
+ mst_abs, /* Generally absolute (nonrelocatable) */
+ /* GDB uses mst_solib_trampoline for the start address of a shared
+ library trampoline entry. Breakpoints for shared library functions
+ are put there if the shared library is not yet loaded.
+ After the shared library is loaded, lookup_minimal_symbol will
+ prefer the minimal symbol from the shared library (usually
+ a mst_text symbol) over the mst_solib_trampoline symbol, and the
+ breakpoints will be moved to their true address in the shared
+ library via breakpoint_re_set. */
+ mst_solib_trampoline, /* Shared library trampoline code */
+ /* For the mst_file* types, the names are only guaranteed to be unique
+ within a given .o file. */
+ mst_file_text, /* Static version of mst_text */
+ mst_file_data, /* Static version of mst_data */
+ mst_file_bss /* Static version of mst_bss */
+};
+
/* Define a simple structure used to hold some very basic information about
all defined global symbols (text, data, bss, abs, etc). The only required
information is the general_symbol_info.
@@ -268,37 +288,7 @@
char *filename;
#endif

- /* Classification types for this symbol. These should be taken as "advisory
- only", since if gdb can't easily figure out a classification it simply
- selects mst_unknown. It may also have to guess when it can't figure out
- which is a better match between two types (mst_data versus mst_bss) for
- example. Since the minimal symbol info is sometimes derived from the
- BFD library's view of a file, we need to live with what information bfd
- supplies. */
-
- enum minimal_symbol_type
- {
- mst_unknown = 0, /* Unknown type, the default */
- mst_text, /* Generally executable instructions */
- mst_data, /* Generally initialized data */
- mst_bss, /* Generally uninitialized data */
- mst_abs, /* Generally absolute (nonrelocatable) */
- /* GDB uses mst_solib_trampoline for the start address of a shared
- library trampoline entry. Breakpoints for shared library functions
- are put there if the shared library is not yet loaded.
- After the shared library is loaded, lookup_minimal_symbol will
- prefer the minimal symbol from the shared library (usually
- a mst_text symbol) over the mst_solib_trampoline symbol, and the
- breakpoints will be moved to their true address in the shared
- library via breakpoint_re_set. */
- mst_solib_trampoline, /* Shared library trampoline code */
- /* For the mst_file* types, the names are only guaranteed to be unique
- within a given .o file. */
- mst_file_text, /* Static version of mst_text */
- mst_file_data, /* Static version of mst_data */
- mst_file_bss /* Static version of mst_bss */
- }
- type BYTE_BITFIELD;
+ ENUM_BITFIELD(minimal_symbol_type) type : 8;

/* Minimal symbols with the same hash key are kept on a linked
list. This is the link. */
@@ -321,7 +311,7 @@
/* Different name domains for symbols. Looking up a symbol specifies a
domain and ignores symbol definitions in other name domains. */

-typedef enum
+typedef enum domain_enum_tag
{
/* UNDEF_DOMAIN is used when a domain has not been discovered or
none of the following apply. This usually indicates an error either
@@ -578,11 +568,11 @@

/* Domain code. */

- domain_enum domain BYTE_BITFIELD;
+ ENUM_BITFIELD(domain_enum_tag) domain : 6;

/* Address class */

- enum address_class aclass BYTE_BITFIELD;
+ ENUM_BITFIELD(address_class) aclass : 6;

/* Line number of definition. FIXME: Should we really make the assumption
that nobody will try to debug files longer than 64K lines? What about
@@ -655,11 +645,11 @@

/* Name space code. */

- domain_enum domain BYTE_BITFIELD;
+ ENUM_BITFIELD(domain_enum_tag) domain : 6;

/* Address class (for info_symbols) */

- enum address_class aclass BYTE_BITFIELD;
+ ENUM_BITFIELD(address_class) aclass : 6;

};

--h7K2nks22828.1061347786/int-mx1.corp.redhat.com--