PROCESSOR-SDK-J784S4: Size of C++ source files

Hi Thierry,

Just to confirm - this is how the code is roughly structured? And the change you are making would be removing the for loop in the init function to another file?

init() {
    SE/SA param intialization
    for() {
        MATHLIB_sin()
        MATHLIB_cos()
    }
}

kernel() {
    for() {
        Processing code use SE/SA
    }
}

Thierry BERNIER said:

I see in MATHlib inline functions that their code is put in a dedicated text section. (something like "text;optci")

Can you point to where you are seeing this?

Best,

Asha

Hi Asha,

yes, the is my scheme. More detailed the code is like that in a "file.cpp" (C++) :

namespace {  // C++ ODR 

static struct Tab {
  float k[xxx];
  xxx sesa_tmpl[xxx];
  init();
} tab;

static init_constants() {
  { fill tab.k[] using a small kernel made of copy/mix of MATHlib inlines }
}

Tab::init() {
  init_constants(); // Call a function of the same file to fill tab.k
  { here-code to prepare SE/SA templates, filling tab_sesa_tmpl[] }
}

static kernel() {
  { use tab.k[] and tab.sesa_tmpl[] }
}

} // namespace

void API () {   // Public/exported C-function
  init();
  for (...) kernel();
}

In the "fast version", the init_constants() is left outside in another file, passing it tab.k[] as ptr argument, to fill it.

Extract of MATH_sin from MATHlib_09_02_00_04 :

(...)

static inline float sinsp_i(float a);

#ifndef __cplusplus /* FOR PROTECTION PURPOSE - C++ NOT SUPPORTED. */
#pragma CODE_SECTION(sinsp_i, ".text:optci");
#endif

(...)

NB: I am using  CGT version 3.1.0. I will try with 4.1.0.

Hi Thierry,

Yes if you are using the 9.2 SDK, use the 4.1.0.LTS compiler as this is what is packaged with the SDK (and what we will use for validation). 

Also, as a sidenote, do note that the sinsp_i function is a scalar function derived from the C66x implementation of sin, and not the "vectorized" version that is optimized for the C7x processor. 

I'm pulling in our compiler team to understand the main issue. Are you measuring the difference in terms of cycle counts? 

Best,

Asha

For this source file ...

Thierry BERNIER said:

In the same C++ source file (around 800 lines), I have :

• a C7X kernel code inside a C++ kernel() function,
• and an init() function to prepare a context for that kernel.

... please follow the directions in the article How to Submit a Compiler Test Case.  But please do it two times.  Once in original form.  And again with these changes ...

Thierry BERNIER said:

If I put the part of the init() function dealing with the array of constants calculation, inside another source file (separate compilation), without changing the kernel() function, then the execution time of kernel() is better, down to 58 units.

Thanks and regards,

-George

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