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author | Arlie Davis <arlied@google.com> | 2015-09-17 15:19:24 -0700 |
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committer | Andreas Boll <andreas.boll.dev@gmail.com> | 2016-01-21 15:03:53 +0100 |
commit | daa775b58e6dcc800dd611678b32cb1c5184f5b0 (patch) | |
tree | 7be0b3e9aa6a19610f5239db9ec82e609e431bab /src/mapi | |
parent | daa0fd7843dfc3f2f209a1b755df01f4dbc8122f (diff) | |
download | external_mesa3d-daa775b58e6dcc800dd611678b32cb1c5184f5b0.zip external_mesa3d-daa775b58e6dcc800dd611678b32cb1c5184f5b0.tar.gz external_mesa3d-daa775b58e6dcc800dd611678b32cb1c5184f5b0.tar.bz2 |
mesa: Reduce libGL.so binary size by about 15%
This patch significantly reduces the size of the libGL.so binary. It does
not change the (externally visible) behavior of libGL.so at all.
gl_gentable.py generates a function, _glapi_create_table_from_handle.
This function allocates a large dispatch table, consisting of 1300 or so
function pointers, and fills this dispatch table by doing symbol lookups
on a given shared library. Previously, gl_gentable.py would generate a
single, very large _glapi_create_table_from_handle function, with a short
cluster of lines for each entry point (function). The idiom it generates
was a NULL check, a call to snprintf, a call to dlsym / GetProcAddress,
and then a store into the dispatch table. Since this function processes
a large number of entry points, this code is duplicated many times over.
We can encode the same information much more compactly, by using a lookup
table. The previous total size of _glapi_create_table_from_handle on x64
was 125848 bytes. By using a lookup table, the size of
_glapi_create_table_from_handle (and the related lookup tables) is reduced
to 10840 bytes. In other words, this enormous function is reduced by 91%.
The size of the entire libGL.so binary (measured when stripped) itself drops
by 15%.
So the purpose of this change is to reduce the binary size, which frees up
disk space, memory, etc.
size lib/libGL.so.1.2.0 on my system shows (Andreas)
text data bss dec hex filename
565947 11256 2720 579923 8d953 lib/libGL.so.1.2.0 before
469211 21848 2720 493779 788d3 lib/libGL.so.1.2.0 after
v2: Incorporate Matt's feedback.
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Jeremy Huddleston Sequoia <jeremyhu@apple.com>
Tested-by: Jeremy Huddleston Sequoia <jeremyhu@apple.com>
Signed-off-by: Andreas Boll <andreas.boll.dev@gmail.com>
Diffstat (limited to 'src/mapi')
-rw-r--r-- | src/mapi/glapi/gen/gl_gentable.py | 57 |
1 files changed, 41 insertions, 16 deletions
diff --git a/src/mapi/glapi/gen/gl_gentable.py b/src/mapi/glapi/gen/gl_gentable.py index 1b3eb72..7cd475a 100644 --- a/src/mapi/glapi/gen/gl_gentable.py +++ b/src/mapi/glapi/gen/gl_gentable.py @@ -113,6 +113,9 @@ __glapi_gentable_set_remaining_noop(struct _glapi_table *disp) { dispatch[i] = p.v; } +""" + +footer = """ struct _glapi_table * _glapi_create_table_from_handle(void *handle, const char *symbol_prefix) { struct _glapi_table *disp = calloc(_glapi_get_dispatch_table_size(), sizeof(_glapi_proc)); @@ -123,27 +126,28 @@ _glapi_create_table_from_handle(void *handle, const char *symbol_prefix) { if(symbol_prefix == NULL) symbol_prefix = ""; -""" -footer = """ - __glapi_gentable_set_remaining_noop(disp); - - return disp; -} -""" + /* Note: This code relies on _glapi_table_func_names being sorted by the + * entry point index of each function. + */ + for (int func_index = 0; func_index < GLAPI_TABLE_COUNT; ++func_index) { + const char *name = _glapi_table_func_names[func_index]; + void ** procp = &((void **)disp)[func_index]; -body_template = """ - if(!disp->%(name)s) { - void ** procp = (void **) &disp->%(name)s; - snprintf(symboln, sizeof(symboln), "%%s%(entry_point)s", symbol_prefix); + snprintf(symboln, sizeof(symboln), \"%s%s\", symbol_prefix, name); #ifdef _WIN32 *procp = GetProcAddress(handle, symboln); #else *procp = dlsym(handle, symboln); #endif } + __glapi_gentable_set_remaining_noop(disp); + + return disp; +} """ + class PrintCode(gl_XML.gl_print_base): def __init__(self): @@ -180,12 +184,33 @@ class PrintCode(gl_XML.gl_print_base): def printBody(self, api): - for f in api.functionIterateByOffset(): - for entry_point in f.entry_points: - vars = { 'entry_point' : entry_point, - 'name' : f.name } - print body_template % vars + # Determine how many functions have a defined offset. + func_count = 0 + for f in api.functions_by_name.itervalues(): + if f.offset != -1: + func_count += 1 + + # Build the mapping from offset to function name. + funcnames = [None] * func_count + for f in api.functions_by_name.itervalues(): + if f.offset != -1: + if not (funcnames[f.offset] is None): + raise Exception("Function table has more than one function with same offset (offset %d, func %s)" % (f.offset, f.name)) + funcnames[f.offset] = f.name + + # Check that the table has no gaps. We expect a function at every offset, + # and the code which generates the table relies on this. + for i in xrange(0, func_count): + if funcnames[i] is None: + raise Exception("Function table has no function at offset %d" % (i)) + + print "#define GLAPI_TABLE_COUNT %d" % func_count + print "static const char * const _glapi_table_func_names[GLAPI_TABLE_COUNT] = {" + for i in xrange(0, func_count): + print " /* %5d */ \"%s\"," % (i, funcnames[i]) + print "};" + return |