Mailing List Archive

* cipher/cipher-gcm-ppc.c (_gcry_ghash_ppc_vpmsum): Increament
'buf' pointer right after use; Use 'for' loop for inner 4-blocks
loop to allow compiler to better optimize loop.
--

Benchmark on POWER9:

Before:
| nanosecs/byte mebibytes/sec cycles/byte
GMAC_AES | 0.226 ns/B 4211 MiB/s 0.521 c/B

After:
| nanosecs/byte mebibytes/sec cycles/byte
GMAC_AES | 0.224 ns/B 4248 MiB/s 0.516 c/B

Signed-off-by: Jussi Kivilinna <jussi.kivilinna@iki.fi>
---
cipher/cipher-gcm-ppc.c | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/cipher/cipher-gcm-ppc.c b/cipher/cipher-gcm-ppc.c
index 4f75e95c..06bf5eb1 100644
--- a/cipher/cipher-gcm-ppc.c
+++ b/cipher/cipher-gcm-ppc.c
@@ -437,6 +437,7 @@ _gcry_ghash_ppc_vpmsum (byte *result, void *gcm_table,
in1 = vec_load_he (16, buf);
in2 = vec_load_he (32, buf);
in3 = vec_load_he (48, buf);
+ buf += 64;
in0 = vec_be_swap(in0, bswap_const);
in1 = vec_be_swap(in1, bswap_const);
in2 = vec_be_swap(in2, bswap_const);
@@ -464,17 +465,13 @@ _gcry_ghash_ppc_vpmsum (byte *result, void *gcm_table,
Xh3 = asm_xor (Xh3, Xh1);

/* Gerald Estrin's scheme for parallel multiplication of polynomials */
- while (1)
+ for (; blocks_remaining >= 4; blocks_remaining -= 4)
{
- buf += 64;
- blocks_remaining -= 4;
- if (!blocks_remaining)
- break;
-
in0 = vec_load_he (0, buf);
in1 = vec_load_he (16, buf);
in2 = vec_load_he (32, buf);
in3 = vec_load_he (48, buf);
+ buf += 64;
in1 = vec_be_swap(in1, bswap_const);
in2 = vec_be_swap(in2, bswap_const);
in3 = vec_be_swap(in3, bswap_const);
--
2.37.2


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