From: Xiaole He <hexiaole1994@126.com>
To: libabigail@sourceware.org
Cc: Xiaole He <hexiaole1994@126.com>, Xiaole He <hexiaole@kylinos.cn>
Subject: [PATCH] abg-reader: optimize if construction
Date: Sun, 16 Oct 2022 06:47:03 +0000 [thread overview]
Message-ID: <20221016064703.67180-1-hexiaole1994@126.com> (raw)
In 'build_enum_type_decl' function of 'src/abg-reader.cc', the
'for loop' walk through all the child nodes of the '<enum-decl>' for
seeking '<underlying-type>' and '<enumerator>':
/* original src/abg-reader.cc begin */
static enum_type_decl_sptr
build_enum_type_decl(read_context& ctxt,
const xmlNodePtr node,
bool add_to_current_scope)
{
...
for (xmlNodePtr n = xmlFirstElementChild(node);
n;
n = xmlNextElementSibling(n))
{
if (xmlStrEqual(n->name, BAD_CAST("underlying-type")))
{
...
}
if (xmlStrEqual(n->name, BAD_CAST("enumerator")))
{
...
}
}
...
}
/* original src/abg-reader.cc end */
Here uses 2 separate 'if' statements for seeking, that is, for any
child node of the '<enum-decl>', there involves 2 'if' comparations.
Because the child node of the '<enum-decl>' is either
'<underlying-type>' or '<enumerator>', there would be a slight
optimization when use 'if-else if' construction instead, like below:
/* optimized src/abg-reader.cc begin */
for (xmlNodePtr n = xmlFirstElementChild(node);
n;
n = xmlNextElementSibling(n))
{
if (xmlStrEqual(n->name, BAD_CAST("underlying-type")))
{
...
}
else if (xmlStrEqual(n->name, BAD_CAST("enumerator")))
{
...
}
}
/* optimized src/abg-reader.cc end */
Supposing there has the test case:
/* test case begin */
<abi-instr version='1.0'>
<enum-decl name='E' filepath='../../abitests/test-enum0-v0.cc' line='1' column='6' id='type-id-2'>
<underlying-type type-id='type-id-1'/>
<enumerator name='e0' value='0'/>
<enumerator name='e2' value='1'/>
</enum-decl>
</abi-instr>
/* test case end */
When parsing the '<underlying-type>' xml tag, for the original
'src/abg-reader.cc', there involves 2 'if' comparations. But involves
only 1 'if' comparation for the optimized 'src/abg-reader.cc'.
Signed-off-by: Xiaole He <hexiaole@kylinos.cn>
Tested-by: Xiaole He <hexiaole@kylinos.cn>
---
src/abg-reader.cc | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/src/abg-reader.cc b/src/abg-reader.cc
index b55808b9..4afa427a 100644
--- a/src/abg-reader.cc
+++ b/src/abg-reader.cc
@@ -4602,8 +4602,7 @@ build_enum_type_decl(read_context& ctxt,
base_type_id = CHAR_STR(a);
continue;
}
-
- if (xmlStrEqual(n->name, BAD_CAST("enumerator")))
+ else if (xmlStrEqual(n->name, BAD_CAST("enumerator")))
{
string name;
int64_t value = 0;
--
2.27.0
next reply other threads:[~2022-10-16 6:49 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-16 6:47 Xiaole He [this message]
2022-10-17 14:14 ` Dodji Seketeli
2022-10-18 3:25 ` Xiaole He
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