Frp Fast Call V.01 Download

This function is a central one to my code and gets called thousands of times per step in my program and my program performs millions of steps. Thus I want to have the LEAST overhead possible, hence why I'm wasting time worrying about the overhead of inlining v. transforming the code into a macro.

Calling an inline function may or may not generate a function call, which typically incurs a very small amount of overhead. The exact situations under which an inline function actually gets inlined vary depending on the compiler; most make a good-faith effort to inline small functions (at least when optimization is enabled), but there is no requirement that they do so (C99, 6.7.4):

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Simple mathmatical operations that are chained together using functions are often inlined by the compiler, especially if the function is only called once in the translation step. So, I wouldn't be surprised that the compiler takes inlining decisions for you, regardless of weather the keyword is supplied or not.

The best way to answer your question is to benchmark both approaches to see which is actually faster in your application, using your test data. Predictions about performance are notoriously unreliable except at the coarsest levels.

Assuming you find that, the first thing to do is get rid of the calls to pow that you found on the stack.(In general, what it does is take the log of the first argument, multiply it by the second argument, and exp of that, or something that does the same thing. The log and exp could well be done by some kind of series involving a lot of arithmetic. It looks for special cases, of course, but it's still going to take longer than you would.)That alone should give you around an order of magnitude speedup.

As I understand it from some guys who write compilers, once you call a function from inside it is not very likely your code will be inlined anyway. But, that is why you should not use a macro. Macros remove information and leave the compiler with far fewer options to optimize. With multi-pass compilers and whole program optimizations they will know that inlining your code will cause a failed branch prediction or a cache miss or other black magic forces modern CPUs use to go fast. I think everyone is right to point out that the code above is not optimal anyway, so that is where the focus should be.

There are subtle differences in how various compilers implement these conventions, so it is often difficult to interface code which is compiled by different compilers. On the other hand, conventions which are used as an API standard (such as stdcall) are very uniformly implemented.

Prior to microcomputers, the machine manufacturer generally provided an operating system and compilers for several programming languages. The calling convention(s) for each platform were those defined by the manufacturer's programming tools.

Early microcomputers before the Commodore Pet and Apple II generally came without an OS or compilers. The IBM PC came with Microsoft's fore-runner to Windows, the Disk Operating System (DOS), but it did not come with a compiler. The only hardware standard for IBM PC-compatible machines was defined by the Intel processors (8086, 80386) and the literal hardware IBM shipped. Hardware extensions and all software standards (save for a BIOS calling convention) were thrown open to market competition.

A multitude of independent software firms offered operating systems, compilers for many programming languages, and applications. Many different calling schemes were implemented by the firms, often mutually exclusive, based on different requirements, historical practices, and programmer creativity.

The cdecl (which stands for C declaration) is a calling convention for the C programming language and is used by many C compilers for the x86 architecture.[1] In cdecl, subroutine arguments are passed on the stack. If the return values are Integer values or memory addresses they are put into the EAX register by the callee, whereas floating point values are put in the ST0 x87 register. Registers EAX, ECX, and EDX are caller-saved, and the rest are callee-saved. The x87 floating point registers ST0 to ST7 must be empty (popped or freed) when calling a new function, and ST1 to ST7 must be empty on exiting a function. ST0 must also be empty when not used for returning a value.

The cdecl calling convention is usually the default calling convention for x86 C compilers, although many compilers provide options to automatically change the calling conventions used. To manually define a function to be cdecl, some support the following syntax:

There are some variations in the interpretation of cdecl. As a result, x86 programs compiled for different operating system platforms and/or by different compilers can be incompatible, even if they both use the "cdecl" convention and do not call out to the underlying environment.

In regard to how to return values, some compilers return simple data structures with a length of 2 registers or less in the register pair EAX:EDX, and larger structures and class objects requiring special treatment by the exception handler (e.g., a defined constructor, destructor, or assignment) are returned in memory. To pass "in memory", the caller allocates memory and passes a pointer to it as a hidden first parameter; the callee populates the memory and returns the pointer, popping the hidden pointer when returning.[2]

In Linux, GCC sets the de facto standard for calling conventions. Since GCC version 4.5, the stack must be aligned to a 16-byte boundary when calling a function (previous versions only required a 4-byte alignment).[1][3]

In these conventions, the callee cleans up the arguments from the stack. Functions which use these conventions are easy to recognize in ASM code because they will unwind the stack after returning. The x86 .mw-parser-output .monospaced{font-family:monospace,monospace}ret instruction allows an optional 16-bit parameter that specifies the number of stack bytes to release after returning to the caller. Such code looks like this:

Conventions entitled fastcall or register have not been standardized, and have been implemented differently, depending on the compiler vendor.[1] Typically register based calling conventions pass one or more arguments in registers which reduces the number of memory accesses required for the call and thus make them usually faster.

Based on the Borland Pascal programming language's calling convention, the parameters are pushed on the stack in left-to-right order (opposite of cdecl), and the callee is responsiblefor removing them from the stack.

This calling convention was common in the following 16-bit APIs: OS/2 1.x, Microsoft Windows 3.x, and Borland Delphi version 1.x. Modern versions of the Windows API use stdcall, which still has the callee restoring the stack as in the Pascal convention, but the parameters are now pushed right to left.

The stdcall[5] calling convention is a variation on the Pascal calling convention in which the callee is responsible for cleaning up the stack, but the parameters are pushed onto the stack in right-to-left order, as in the _cdecl calling convention. Registers EAX, ECX, and EDX are designated for use within the function. Return values are stored in the EAX register.

Microsoft __fastcall convention (aka __msfastcall) passes the first two arguments (evaluated left to right) that fit, into ECX and EDX.[6] Remaining arguments are pushed onto the stack from right to left. When the compiler compiles for IA64 or AMD64, it ignores the __fastcall keyword (or any other calling convention keyword aside from __vectorcall) and uses the default 64-bit calling convention instead.

Other compilers like GCC,[7] Clang,[8] and ICC[citation needed] provide similar "fastcall" calling conventions, although they are not necessarily compatible with each other or with Microsoft fastcall.[9]

The first two arguments are passed in the left to right order, and the third argument is pushed on the stack. There is no stack cleanup, as stack cleanup is performed by the callee. The disassembly of the callee function is:

In Visual Studio 2013, Microsoft introduced the __vectorcall calling convention in response to efficiency concerns from game, graphic, video/audio, and codec developers. The scheme allows for larger vector types (float, double, __m128, __m256) to be passed in registers as opposed to on the stack.[10]

For IA-32 and x64 code, __vectorcall is similar to __fastcall and the original x64 calling conventions respectively, but extends them to support passing vector arguments using SIMD registers. In IA-32, the integer values are passed as usual, and the first six SIMD (XMM/YMM0-5) registers hold up to six floating-point, vector, or HVA values sequentially from left to right, regardless of actual positions caused by, e.g. an int argument appearing between them. In x64, however, the rule from the original x64 convention still apply, so that XMM/YMM0-5 only hold floating-point, vector, or HVA arguments when they happen to be the first through the sixth.[11]

__vectorcall adds support for passing homogeneous vector aggregate (HVA) values, which are composite types (structs) consisting solely of up to four identical vector types, using the same six registers. Once the registers have been allocated for vector type arguments, the unused registers are allocated to HVA arguments from left to right. The positioning rules still apply. Resulting vector type and HVA values are returned using the first four XMM/YMM registers.[11]

Evaluating arguments from left to right, it passes three arguments via EAX, EDX, ECX. Remaining arguments are pushed onto the stack, also left to right.[15] It is the default calling convention of the 32-bit compiler of Delphi, where it is known as register. This calling convention is also used by Embarcadero's C++Builder, where it is called __fastcall.[16] In this compiler, Microsoft's fastcall can be used as __msfastcall.[17] e24fc04721