[PATCH v3 5/5] crypto: lib/sha256 - Unroll LOAD and BLEND loops

[Arvind Sankar]

Unrolling the LOAD and BLEND loops improves performance by ~8% on x86_64
(tested on Broadwell Xeon) while not increasing code size too much.

Signed-off-by: Arvind Sankar <nivedita@xxxxxxxxxxxx>
Reviewed-by: Eric Biggers <ebiggers@xxxxxxxxxx>
---
 lib/crypto/sha256.c | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/lib/crypto/sha256.c b/lib/crypto/sha256.c
index e2e29d9b0ccd..cdef37c05972 100644
--- a/lib/crypto/sha256.c
+++ b/lib/crypto/sha256.c
@@ -76,12 +76,28 @@ static void sha256_transform(u32 *state, const u8 *input, u32 *W)
 	int i;
 
 	/* load the input */
-	for (i = 0; i < 16; i++)
-		LOAD_OP(i, W, input);
+	for (i = 0; i < 16; i += 8) {
+		LOAD_OP(i + 0, W, input);
+		LOAD_OP(i + 1, W, input);
+		LOAD_OP(i + 2, W, input);
+		LOAD_OP(i + 3, W, input);
+		LOAD_OP(i + 4, W, input);
+		LOAD_OP(i + 5, W, input);
+		LOAD_OP(i + 6, W, input);
+		LOAD_OP(i + 7, W, input);
+	}
 
 	/* now blend */
-	for (i = 16; i < 64; i++)
-		BLEND_OP(i, W);
+	for (i = 16; i < 64; i += 8) {
+		BLEND_OP(i + 0, W);
+		BLEND_OP(i + 1, W);
+		BLEND_OP(i + 2, W);
+		BLEND_OP(i + 3, W);
+		BLEND_OP(i + 4, W);
+		BLEND_OP(i + 5, W);
+		BLEND_OP(i + 6, W);
+		BLEND_OP(i + 7, W);
+	}
 
 	/* load the state into our registers */
 	a = state[0];  b = state[1];  c = state[2];  d = state[3];
-- 
2.26.2