Avoid duplicate definitions of JSCONST_n*Hash and QeTable variables.

Avoid duplicate definitions of JSCONST_n*Hash and QeTable variables.

QeTable is a 752 byte array that was defined in a header file. This
caused it to be instantiated by the VC++ compiler 12 times, wasting
8,272 bytes of space in the data segment. Because 'const' implies
'static' this did not cause any duplicate symbol errors.

JSCONST_n*HASH are a set of eight variables that are defined in a header
file. This causes them to be replicated 15 times. The variables
themselves are tiny but they are dynamically initialized and this
dynamic initialization code is replicated 15 times.

When tested on pdfium_test.exe the effect of this change is to:
Reduce the .text (code) segment by 3,616 bytes.
Reduce the .rdata section by 8,656 bytes.
Reduce the total binary file size by 13312 bytes.

These are the worst offenders for pdf.dll as shown in:
https://drive.google.com/open?id=1BvubxoA2SU_2e4T5cq7jHTjc1TlT0qOndpIfX3DMeA8&authuser=0

This will also drastically simplify the list of work to be done
for bug 441899 (getting rid of initializers).

BUG=441988
R=bo_xu@foxitsoftware.com

Committed: https://pdfium.googlesource.com/pdfium/+/7be67b2e4f496cb638b365264ce835e3b23a555e

[brucedawson, 2014-12-13 01:30:09]

brucedawson@chromium.org changed reviewers:
+ bo_xu@foxitsoftware.com

[brucedawson, 2014-12-13 01:33:58]

This is a small optimization which saves a bit of space and also makes bug
441899 more comprehensible.

[Bo Xu, 2014-12-13 01:47:37]

https://codereview.chromium.org/802013002/diff/1/core/src/fxcodec/jbig2/JBig2...
File core/src/fxcodec/jbig2/JBig2_GeneralDecoder.cpp (right):

https://codereview.chromium.org/802013002/diff/1/core/src/fxcodec/jbig2/JBig2...
core/src/fxcodec/jbig2/JBig2_GeneralDecoder.cpp:14: extern const JBig2ArithQe
QeTable[] = {
The "extern" keyword may not be necessary in the definition?

https://codereview.chromium.org/802013002/diff/1/fpdfsdk/src/javascript/globa...
File fpdfsdk/src/javascript/global.cpp (right):

https://codereview.chromium.org/802013002/diff/1/fpdfsdk/src/javascript/globa...
fpdfsdk/src/javascript/global.cpp:19: extern const unsigned int
JSCONST_nStringHash = JS_CalcHash(VALUE_NAME_STRING,wcslen(VALUE_NAME_STRING));
Similar here?

[brucedawson, 2014-12-13 01:56:25]

https://codereview.chromium.org/802013002/diff/1/core/src/fxcodec/jbig2/JBig2...
File core/src/fxcodec/jbig2/JBig2_GeneralDecoder.cpp (right):

https://codereview.chromium.org/802013002/diff/1/core/src/fxcodec/jbig2/JBig2...
core/src/fxcodec/jbig2/JBig2_GeneralDecoder.cpp:14: extern const JBig2ArithQe
QeTable[] = {
On 2014/12/13 01:47:37, Bo Xu wrote:
> The "extern" keyword may not be necessary in the definition?

True, it's only needed on the declaration, as long as the declaration is seen by
the compiler before the definition -- i.e.; as long as the header file is
included before the definition, which is a best-practice.

I think I like having it because it makes it explicit that the array needs to be
externally visible. Otherwise it is very subtle (because const implies static).

Your call.

https://codereview.chromium.org/802013002/diff/1/fpdfsdk/src/javascript/globa...
File fpdfsdk/src/javascript/global.cpp (right):

https://codereview.chromium.org/802013002/diff/1/fpdfsdk/src/javascript/globa...
fpdfsdk/src/javascript/global.cpp:19: extern const unsigned int
JSCONST_nStringHash = JS_CalcHash(VALUE_NAME_STRING,wcslen(VALUE_NAME_STRING));
I just noticed that these lines are well over 80 columns, but they were before
also. I assume that I should reformat them to the chromium coding standard as
part of the checkin.

[Bo Xu, 2014-12-13 03:39:55]

LGTM

https://codereview.chromium.org/802013002/diff/1/core/src/fxcodec/jbig2/JBig2...
File core/src/fxcodec/jbig2/JBig2_GeneralDecoder.cpp (right):

https://codereview.chromium.org/802013002/diff/1/core/src/fxcodec/jbig2/JBig2...
core/src/fxcodec/jbig2/JBig2_GeneralDecoder.cpp:14: extern const JBig2ArithQe
QeTable[] = {
On 2014/12/13 01:56:25, brucedawson wrote:
> On 2014/12/13 01:47:37, Bo Xu wrote:
> > The "extern" keyword may not be necessary in the definition?
> 
> True, it's only needed on the declaration, as long as the declaration is seen
by
> the compiler before the definition -- i.e.; as long as the header file is
> included before the definition, which is a best-practice.
> 
> I think I like having it because it makes it explicit that the array needs to
be
> externally visible. Otherwise it is very subtle (because const implies
static).
> 
> Your call.

Fair enough

https://codereview.chromium.org/802013002/diff/1/fpdfsdk/src/javascript/globa...
File fpdfsdk/src/javascript/global.cpp (right):

https://codereview.chromium.org/802013002/diff/1/fpdfsdk/src/javascript/globa...
fpdfsdk/src/javascript/global.cpp:19: extern const unsigned int
JSCONST_nStringHash = JS_CalcHash(VALUE_NAME_STRING,wcslen(VALUE_NAME_STRING));
On 2014/12/13 01:56:25, brucedawson wrote:
> I just noticed that these lines are well over 80 columns, but they were before
> also. I assume that I should reformat them to the chromium coding standard as
> part of the checkin.

There is a separate thread by thakis@ requesting reformatting the entire pdfium
code base after XFA is officially lands, so I don't think we have to worry about
this now.

[brucedawson, 2014-12-13 05:21:27]

The CQ bit was checked by brucedawson@chromium.org

[commit-bot: I haz the power, 2014-12-13 05:24:31]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-12-13 05:24:31]

Commit queue rejected this change because it did not recognize the base URL.
Please commit your change manually.

[brucedawson, 2014-12-13 05:30:43]

Committed patchset #1 (id:1) manually as
7be67b2e4f496cb638b365264ce835e3b23a555e (presubmit successful).