x86_64-gcc.c

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/*
 * x86_64 BIGNUM accelerator version 0.1, December 2002.
 *
 * Implemented by Andy Polyakov <[e-mail]> for the OpenSSL
 * project.
 *
 * Rights for redistribution and usage in source and binary forms are
 * granted according to the OpenSSL license. Warranty of any kind is
 * disclaimed.
 *
 * Q. Version 0.1? It doesn't sound like Andy, he used to assign real
 *    versions, like 1.0...
 * A. Well, that's because this code is basically a quick-n-dirty
 *    proof-of-concept hack. As you can see it's implemented with
 *    inline assembler, which means that you're bound to GCC and that
 *    there might be enough room for further improvement.
 *
 * Q. Why inline assembler?
 * A. x86_64 features own ABI which I'm not familiar with. This is
 *    why I decided to let the compiler take care of subroutine
 *    prologue/epilogue as well as register allocation. For reference.
 *    Win64 implements different ABI for AMD64, different from Linux.
 *
 * Q. How much faster does it get?
 * A. 'apps/openssl speed rsa dsa' output with no-asm:
 *
 *	                  sign    verify    sign/s verify/s
 *	rsa  512 bits   0.0006s   0.0001s   1683.8  18456.2
 *	rsa 1024 bits   0.0028s   0.0002s    356.0   6407.0
 *	rsa 2048 bits   0.0172s   0.0005s     58.0   1957.8
 *	rsa 4096 bits   0.1155s   0.0018s      8.7    555.6
 *	                  sign    verify    sign/s verify/s
 *	dsa  512 bits   0.0005s   0.0006s   2100.8   1768.3
 *	dsa 1024 bits   0.0014s   0.0018s    692.3    559.2
 *	dsa 2048 bits   0.0049s   0.0061s    204.7    165.0
 *
 *    'apps/openssl speed rsa dsa' output with this module:
 *
 *	                  sign    verify    sign/s verify/s
 *	rsa  512 bits   0.0004s   0.0000s   2767.1  33297.9
 *	rsa 1024 bits   0.0012s   0.0001s    867.4  14674.7
 *	rsa 2048 bits   0.0061s   0.0002s    164.0   5270.0
 *	rsa 4096 bits   0.0384s   0.0006s     26.1   1650.8
 *	                  sign    verify    sign/s verify/s
 *	dsa  512 bits   0.0002s   0.0003s   4442.2   3786.3
 *	dsa 1024 bits   0.0005s   0.0007s   1835.1   1497.4
 *	dsa 2048 bits   0.0016s   0.0020s    620.4    504.6
 *
 *    For the reference. IA-32 assembler implementation performs
 *    very much like 64-bit code compiled with no-asm on the same
 *    machine.
 */

#define BN_ULONG unsigned long

/*
 * "m"(a), "+m"(r)	is the way to favor DirectPath