New C++ compiler with inline assembly support
Agner Fog <[email protected]>
| Newsgroups | org.kernel.vger.linux-assembly |
|---|---|
| Message-ID | <[email protected]> |
Intel have just released version 9.0 of their C++ compiler with better
support for inline assembly.
It can compile for the following platforms
- Linux x86 32 bit
- Linux x86 64 bit
- Linux ia64 (Itanium)
- Windows x86 32 bit
- Windows x86 64 bit
- Windows ia64 (Itanium)
I haven't tested it on FreeBSD yet, but I assume that it works on 32 and
64 bit FreeBSD as well.
In Linux, you now have the choice between MASM syntax and AT&T syntax
for inline assembly. MASM syntax is almost the same as NASM. If you
choose MASM syntax, you can use the same C++ file with inline assembly
in both Linux and Windows. It can even translate MASM syntax assembly to
AT&T syntax, and this more reliably than any other translation tools I
have seen yet.
To use MASM syntax under Linux, simply use the command line option
-use-msasm
Example:
int addnumbers (int a, int b) {
return a+b;}
Same with inline assembly in MASM syntax:
int addnumbers (int a, int b) {
__asm {
mov eax, a
add eax, b
}
}
This will work in both Linux and Windows, 32 and 64 bit. So you can use
the same C++/asm file on all platforms. It takes care of the differences
in calling conventions between the different platforms, and it
automatically pushes and pops any non-volatile registers that you use in
your code. This makes Linux assembly much easier! You can make the most
of your program in C++ and make the critical innermost loop with inline
assembly.
In 64-bit Linux, function parameters are transferred in registers rdi,
rsi, rdx, rcx, r8, r9, xmm0-xmm7. If you know this, you can optimize the
above example:
int addnumbers (int a, int b) {
__asm {
lea eax, [rdi+rsi]
}
}
But then your code is no longer platform independent, of course.
The C++ compiler for Linux is available for free for noncommercial
users. Download it from http://www.intel.com/software/products/noncom/
The C++ compiler for Windows is available with a time limited free
evaluation license from
https://registrationcenter.intel.com/EvalCenter/EvalForm.aspx?ProductID=411
Agner Fog
www.agner.org/assem