e95086b2f
Denys Vlasenko
2025-08-01
Subject
libbb/yescrypt: code shrink
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libbb/yescrypt/alg-sha256.c+9 -4
| @@ -47,9 +47,12 @@ PBKDF2_SHA256(const uint8_t *passwd, size_t passwdlen, | |
| /* Iterate through the blocks. */ | |
| for (i = 0; dkLen != 0; ) { | |
| - | uint64_t U[32 / 8]; |
| - | uint64_t T[32 / 8]; |
| - | uint64_t j; |
| + | long U[32 / sizeof(long)]; |
| + | long T[32 / sizeof(long)]; |
| + | // Do not make these ^^ uint64_t[]. Keep them long[]. |
| + | // Even though the XORing loop below is optimized out, |
| + | // gcc is not smart enough to realize that 64-bit alignment of the stack |
| + | // is no longer useful, and generates ~50 more bytes of code on i386... |
| uint32_t ivec; | |
| size_t clen; | |
| int k; | |
| @@ -64,13 +67,15 @@ PBKDF2_SHA256(const uint8_t *passwd, size_t passwdlen, | |
| //does libbb need a non-vararg version with just one (buf,len)? | |
| if (c > 1) { | |
| + | //in yescrypt, c is always 1, so this if() branch is optimized out |
| + | uint64_t j; |
| /* T_i = U_1 ... */ | |
| memcpy(U, T, 32); | |
| for (j = 2; j <= c; j++) { | |
| /* Compute U_j. */ | |
| hmac_peek_hash(&Phctx, (void*)U, U, 32, NULL); | |
| /* ... xor U_j ... */ | |
| - | for (k = 0; k < 32 / 8; k++) |
| + | for (k = 0; k < 32 / sizeof(long); k++) |
| T[k] ^= U[k]; | |
| //TODO: xorbuf32_aligned_long(T, U); | |
| } | |