f7806f9d8
Denys Vlasenko
2017-01-19
Subject
tls: fix ROL/ROR x86 optimization
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networking/tls_symmetric.h+14 -5
| @@ -7,9 +7,6 @@ | |
| /* The part below is a section of matrixssl-3-7-2b-open/crypto/cryptolib.h | |
| * Changes are flagged with //bbox | |
| - | * TODO: |
| - | * Take a look at "roll %%cl" part... rotates by constant use fewer registers, |
| - | * and on many Intel CPUs rotates by %cl are slower: they take 2 cycles, not 1. |
| */ | |
| /******************************************************************************/ | |
| @@ -28,16 +25,28 @@ | |
| #elif defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__)) && \ | |
| !defined(INTEL_CC) && !defined(PS_NO_ASM) | |
| - | static inline unsigned ROL(unsigned word, int i) |
| + | static ALWAYS_INLINE unsigned ROL(unsigned word, int i) |
| { | |
| + | if (__builtin_constant_p(i)) //box |
| + | // Rotates by constant use fewer registers, |
| + | // and on many Intel CPUs rotates by %cl take 2 cycles, not 1. |
| + | asm ("roll %2,%0" //box |
| + | :"=r" (word) |
| + | :"0" (word),"i" (i)); |
| + | else //box |
| asm ("roll %%cl,%0" | |
| :"=r" (word) | |
| :"0" (word),"c" (i)); | |
| return word; | |
| } | |
| - | static inline unsigned ROR(unsigned word, int i) |
| + | static ALWAYS_INLINE unsigned ROR(unsigned word, int i) |
| { | |
| + | if (__builtin_constant_p(i)) //box |
| + | asm ("rorl %2,%0" //box |
| + | :"=r" (word) |
| + | :"0" (word),"i" (i)); |
| + | else //box |
| asm ("rorl %%cl,%0" | |
| :"=r" (word) | |
| :"0" (word),"c" (i)); | |