Re: [xml] Minor improvement possible
Hi Bruce,
indeed a minor improvement, but that sounds absolutely right, those
data tables are never updated,
Applied and pushed:
https://git.gnome.org/browse/libxml2/commit/?id=8f57103793e1e1b1be478f1feb607d19d725d048
thanks a lot,
Daniel
On Thu, Jan 05, 2017 at 03:00:20PM -0800, Bruce Dawson via xml wrote:
> The constant array xmlUnicodeBlocks is not marked as 'const' so it ends up
> in the read/write data segment instead of the read-only data segment, which
> can lead to it becoming per-process private data instead of image-backed
> shared data.
>
> A patch file (made in the context of Chrome, but it should be applicable to
> libxml2) is attached.
>
> --
> Bruce Dawson
> commit eafa8bbee03e8ebba366be1fb8d5b1596a989a0a
> Author: Bruce Dawson
> Date: Thu Jan 5 11:25:58 2017 -0800
>
> Add const in five places to move 1 KiB to .rdata
>
> xmlUnicodeBlocks is logically const but was not marked as such. This
> fixes that, thus moving it to the read-only data segment.
>
> BUG=677351
>
> diff --git a/third_party/libxml/src/genUnicode.py
> b/third_party/libxml/src/genUnicode.py
> index 56e4e9b..4487eeb 100755
> --- a/third_party/libxml/src/genUnicode.py
> +++ b/third_party/libxml/src/genUnicode.py
> @@ -267,14 +267,14 @@ typedef struct {
> } xmlUnicodeRange;
>
> typedef struct {
> -xmlUnicodeRange *table;
> +const xmlUnicodeRange *table;
> int numentries;
> } xmlUnicodeNameTable;
>
>
> static xmlIntFunc *xmlUnicodeLookup(xmlUnicodeNameTable *tptr, const char
> *tname);
>
> -static xmlUnicodeRange xmlUnicodeBlocks[] = {
> +static const xmlUnicodeRange xmlUnicodeBlocks[] = {
> """ % (webpage, date, sources));
>
> flag = 0
> diff --git a/third_party/libxml/src/xmlunicode.c
> b/third_party/libxml/src/xmlunicode.c
> index ce6e9a4..6d0a96a 100644
> --- a/third_party/libxml/src/xmlunicode.c
> +++ b/third_party/libxml/src/xmlunicode.c
> @@ -29,14 +29,14 @@ typedef struct {
> } xmlUnicodeRange;
>
> typedef struct {
> -xmlUnicodeRange *table;
> +const xmlUnicodeRange *table;
> int numentries;
> } xmlUnicodeNameTable;
>
>
> static xmlIntFunc *xmlUnicodeLookup(xmlUnicodeNameTable *tptr, const char
> *tname);
>
> -static xmlUnicodeRange xmlUnicodeBlocks[] = {
> +static const xmlUnicodeRange xmlUnicodeBlocks[] = {
>{"AegeanNumbers", xmlUCSIsAegeanNumbers},
>{"AlphabeticPresentationForms", xmlUCSIsAlphabeticPresentationForms},
>{"Arabic", xmlUCSIsArabic},
> @@ -945,7 +945,7 @@ static xmlUnicodeNameTable xmlUnicodeCatTbl =
> {xmlUnicodeCats, 36};
> static xmlIntFunc
> *xmlUnicodeLookup(xmlUnicodeNameTable *tptr, const char *tname) {
> int low, high, mid, cmp;
> -xmlUnicodeRange *sptr;
> +const xmlUnicodeRange *sptr;
>
> if ((tptr == NULL) || (tname == NULL)) return(NULL);
>
> ___
> xml mailing list, project page http://xmlsoft.org/
> xml@gnome.org
> https://mail.gnome.org/mailman/listinfo/xml
--
Daniel Veillard | Red Hat Developers Tools http://developer.redhat.com/
veill...@redhat.com | libxml Gnome XML XSLT toolkit http://xmlsoft.org/
http://veillard.com/ | virtualization library http://libvirt.org/
___
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xml@gnome.org
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Re: [xml] Minor improvement possible
I blogged about the importance of adding const in order to get best results here: https://randomascii.wordpress.com/2017/01/08/add-a-const-here-delete-a-const-there/ Some of the post talks about a VC++ compiler bug - ignore that. Note that having constant data in the read-only data segment is a best practice even for single-processing. It's not a huge advantage, but it is strictly better than having logically-const globals in the read/write data segment. On Thu, Jan 5, 2017 at 3:00 PM, Bruce Dawson wrote: > The constant array xmlUnicodeBlocks is not marked as 'const' so it ends up > in the read/write data segment instead of the read-only data segment, which > can lead to it becoming per-process private data instead of image-backed > shared data. > > A patch file (made in the context of Chrome, but it should be applicable > to libxml2) is attached. > > -- > Bruce Dawson > -- Bruce Dawson ___ xml mailing list, project page http://xmlsoft.org/ xml@gnome.org https://mail.gnome.org/mailman/listinfo/xml
[xml] Minor improvement possible
The constant array xmlUnicodeBlocks is not marked as 'const' so it ends up
in the read/write data segment instead of the read-only data segment, which
can lead to it becoming per-process private data instead of image-backed
shared data.
A patch file (made in the context of Chrome, but it should be applicable to
libxml2) is attached.
--
Bruce Dawson
commit eafa8bbee03e8ebba366be1fb8d5b1596a989a0a
Author: Bruce Dawson
Date: Thu Jan 5 11:25:58 2017 -0800
Add const in five places to move 1 KiB to .rdata
xmlUnicodeBlocks is logically const but was not marked as such. This
fixes that, thus moving it to the read-only data segment.
BUG=677351
diff --git a/third_party/libxml/src/genUnicode.py
b/third_party/libxml/src/genUnicode.py
index 56e4e9b..4487eeb 100755
--- a/third_party/libxml/src/genUnicode.py
+++ b/third_party/libxml/src/genUnicode.py
@@ -267,14 +267,14 @@ typedef struct {
} xmlUnicodeRange;
typedef struct {
-xmlUnicodeRange *table;
+const xmlUnicodeRange *table;
intnumentries;
} xmlUnicodeNameTable;
static xmlIntFunc *xmlUnicodeLookup(xmlUnicodeNameTable *tptr, const char
*tname);
-static xmlUnicodeRange xmlUnicodeBlocks[] = {
+static const xmlUnicodeRange xmlUnicodeBlocks[] = {
""" % (webpage, date, sources));
flag = 0
diff --git a/third_party/libxml/src/xmlunicode.c
b/third_party/libxml/src/xmlunicode.c
index ce6e9a4..6d0a96a 100644
--- a/third_party/libxml/src/xmlunicode.c
+++ b/third_party/libxml/src/xmlunicode.c
@@ -29,14 +29,14 @@ typedef struct {
} xmlUnicodeRange;
typedef struct {
-xmlUnicodeRange *table;
+const xmlUnicodeRange *table;
intnumentries;
} xmlUnicodeNameTable;
static xmlIntFunc *xmlUnicodeLookup(xmlUnicodeNameTable *tptr, const char
*tname);
-static xmlUnicodeRange xmlUnicodeBlocks[] = {
+static const xmlUnicodeRange xmlUnicodeBlocks[] = {
{"AegeanNumbers", xmlUCSIsAegeanNumbers},
{"AlphabeticPresentationForms", xmlUCSIsAlphabeticPresentationForms},
{"Arabic", xmlUCSIsArabic},
@@ -945,7 +945,7 @@ static xmlUnicodeNameTable xmlUnicodeCatTbl =
{xmlUnicodeCats, 36};
static xmlIntFunc
*xmlUnicodeLookup(xmlUnicodeNameTable *tptr, const char *tname) {
int low, high, mid, cmp;
-xmlUnicodeRange *sptr;
+const xmlUnicodeRange *sptr;
if ((tptr == NULL) || (tname == NULL)) return(NULL);
___
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