phalcon_call_user_function() optimization

[ghost]

phalcon_call_user_function():

• make use of zend_fcall_info_cache to avoid expensive zend_is_callable() checks
• use return_value_ptr instead of return_value to enable return value optimization

Added phalcon_call_func_aparams:

int phalcon_call_func_aparams(zval **return_value_ptr, const char *func_name, uint func_length, uint param_count, zval **params TSRMLS_DC)

Unlike phalcon_call_func_params it uses zval** (array) to pass the parameters and not variadic arguments (functions with variadic arguments cannot be inlined)

PHALCON_CALL_FUNCTION:

• use phalcon_call_func_params instead of phalcon_call_func_params
• drop return_value (this makes phalcon_call_func_pXXX_ex and phalcon_call_func_pXXX behave identically)
• drop nparams because the number of function arguments is calculated automatically
• do not pass extra NULL when the called function does not need any arguments
• use RETURN_ON_FAILURE macros

PHALCON_CALL_xxx macros:

• merged GNU and non-GNU versions of macros (for gcc-incompatible compilers __builtin_constant_p(s) is #define'd to 0)

Now that PHALCON_CALL_FUNCTION() macro can detect the number of function arguments automatically, we don't need phalcon_call_func_pXXX, phalcon_return_call_func_pXXX, phalcon_call_func_pXXX_noret, phalcon_call_func_pXXX_ex macros — they all have been replaced with PHALCON_CALL_FUNCTION

Other things:

• added phalcon_return_call_function() inline function which is used when the return value of the called function is passed directly into return_value and return_value_ptr. The function is useful when you need to do a cleanup on exception or call failure before returning;
• added PHALCON_CALL_FUNCTIONW() and PHALCON_RETURN_CALL_FUNCTIONW() which do the same as PHALCON_CALL_FUNCTION() and PHALCON_RETURN_CALL_FUNCTION() but do not restore the memory frame;
• added __attribute__((warn_unused_result)) to all phalcon_call_xxx functions, as failure to check the result of the call may lead to unexpected things

How it breaks the API:

Used to be:

PHALCON_INIT_VAR(result);
phalcon_call_func_p1(result, "function", parameter);

Now:

PHALCON_OBS_VAR(result);
PHALCON_CALL_FUNCTION(&result, "function", parameter)

Advantages:

• less memory allocations (return_value is now allocated by Zend; used to be: allocated by Phalcon, desstroyed by Zend, reallocated by Zend)
• less code
• faster function calls due to zend_fcall_info_cache