runtime: AES maphash scramble 3 times on 386

Issue #43130 shows flaky hash not inbalanced on 386 platform,
which is using AES hashing instead of wyhash.
This CL increase the scramble times to 3 that amd64 using right now.

Fixes #43130

Change-Id: I9d012eda99ff71c13a89448f46fcb9c5e7cec921
Reviewed-on: https://go-review.googlesource.com/c/go/+/384075
Trust: mzh <mzh@golangcn.org>
Run-TryBot: mzh <mzh@golangcn.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

diff --git a/src/runtime/asm_386.s b/src/runtime/asm_386.s
index 594cd5ed0d9592fad2a2fa38f71accd0b2ef6471..e16880c950b8472ba0ca58fa1fae4776b9f2f07c 100644 (file)
--- a/src/runtime/asm_386.s
+++ b/src/runtime/asm_386.s
@@ -937,8 +937,9 @@ aes0to15:
        PAND    masks<>(SB)(BX*8), X1
 
 final1:
-       AESENC  X0, X1  // scramble input, xor in seed
-       AESENC  X1, X1  // scramble combo 2 times
+       PXOR    X0, X1  // xor data with seed
+       AESENC  X1, X1  // scramble combo 3 times
+       AESENC  X1, X1
        AESENC  X1, X1
        MOVL    X1, (DX)
        RET
@@ -971,9 +972,13 @@ aes17to32:
        MOVOU   (AX), X2
        MOVOU   -16(AX)(BX*1), X3
 
+       // xor with seed
+       PXOR    X0, X2
+       PXOR    X1, X3
+
        // scramble 3 times
-       AESENC  X0, X2
-       AESENC  X1, X3
+       AESENC  X2, X2
+       AESENC  X3, X3
        AESENC  X2, X2
        AESENC  X3, X3
        AESENC  X2, X2
@@ -1000,10 +1005,15 @@ aes33to64:
        MOVOU   -32(AX)(BX*1), X6
        MOVOU   -16(AX)(BX*1), X7
 
-       AESENC  X0, X4
-       AESENC  X1, X5
-       AESENC  X2, X6
-       AESENC  X3, X7
+       PXOR    X0, X4
+       PXOR    X1, X5
+       PXOR    X2, X6
+       PXOR    X3, X7
+
+       AESENC  X4, X4
+       AESENC  X5, X5
+       AESENC  X6, X6
+       AESENC  X7, X7
 
        AESENC  X4, X4
        AESENC  X5, X5
@@ -1069,7 +1079,12 @@ aesloop:
        DECL    BX
        JNE     aesloop
 
-       // 2 more scrambles to finish
+       // 3 more scrambles to finish
+       AESENC  X4, X4
+       AESENC  X5, X5
+       AESENC  X6, X6
+       AESENC  X7, X7
+
        AESENC  X4, X4
        AESENC  X5, X5
        AESENC  X6, X6