[Lcms-user] One More Possible Important Compiler Warning

[Noel C. <NCa...@Pr...>]

Hi Marti,

 

By the way, there is one more possibly important warning you should
think about addressing for release 2.9, this time issued from the VS
2017 Code Analyzer:

 

c:\dev\prodigital\trunk\libraries\littlecms\src\cmsgamma.c(1153):
warning C6262: Function uses '49196' bytes of stack:  exceeds
/analyze:stacksize '16384'.  Consider moving some data to heap.

 

This is because of the following code, in cmsgamma.c:

 

 

// Maxim number of nodes

#define MAX_NODES_IN_CURVE   4097

 

...

 

// Smooths a curve sampled at regular intervals.

cmsBool  CMSEXPORT cmsSmoothToneCurve(cmsToneCurve* Tab,
cmsFloat64Number lambda)

{

    cmsFloat32Number w[MAX_NODES_IN_CURVE], y[MAX_NODES_IN_CURVE],
z[MAX_NODES_IN_CURVE];

 

 

The w, y, and z arrays are a bit on the large size for stack variables.
I did some reading on Windows stack allocations and the stack may be
quite limited under some conditions.  It's possible the same applies to
other architectures too.

 

I recommend considering changing the code to malloc several temporary
buffers instead of allocating blocks of stack space.  Here's a suggested
implementation using _cmsCalloc / _cmsFree, and which is more structured
and now properly reports all errors.  It passes all tests and
performance is good, per the testbed, though I recommend a very careful
review.  Both the current Github code and proposed new code blocks are
in this file.  Compile the new code for comparative testing by defining
the symbol PRODIGITAL_OPTIMIZATIONS, which can also be used to find the
changes in the source.

 

http://Noel.ProDigitalSoftware.com/temp/cmsgamma_proposed_changes.zip

 

Please let me know if you have questions.

 

-Noel