From: Niels Möller <nisse@lysator.liu.se>
Date: Mon, 13 Jul 2020 20:49:32 +0000 (+0200)
Subject: Keep counter words in registers
X-Git-Tag: nettle_3.7rc1~84
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c23a5f17ab3ec653267cd9131949ee7b5b5c5c27;p=thirdparty%2Fnettle.git

Keep counter words in registers
---

diff --git a/arm/neon/chacha-3core.asm b/arm/neon/chacha-3core.asm
index f1fa5cb8..9d06d5b1 100644
--- a/arm/neon/chacha-3core.asm
+++ b/arm/neon/chacha-3core.asm
@@ -79,8 +79,10 @@ PROLOGUE(_nettle_chacha_3core)
 	vmov	Z1, X1
 	vmov	Y2, X2
 	vmov	Z2, X2
-	vpush	{Z3}
-	vpush	{Y3}
+
+	C Save initial values for the words including the counters.
+	vmov	T2, Y3
+	vmov	T3, Z3
 
 .Loop:
 	C Interleave three blocks. Note that with this scheduling,
@@ -207,26 +209,28 @@ PROLOGUE(_nettle_chacha_3core)
 
 	bhi	.Loop
 
+	C Add updated counters
+	vadd.i32	Y3, Y3, T2
+	vadd.i32	Z3, Z3, T3
+
 	vldm	SRC, {T0,T1,T2,T3}
 	vadd.i32	X0, X0, T0
-	vadd.i32	Y0, Y0, T0
-	vadd.i32	Z0, Z0, T0
 	vadd.i32	X1, X1, T1
-	vadd.i32	Y1, Y1, T1
-	vadd.i32	Z1, Z1, T1
 	vadd.i32	X2, X2, T2
+	vadd.i32	X3, X3, T3
+	vstmia	DST!, {X0,X1,X2,X3}
+
+	vadd.i32	Y0, Y0, T0
+	vadd.i32	Y1, Y1, T1
 	vadd.i32	Y2, Y2, T2
-	vadd.i32	Z2, Z2, T2
+	vstmia	DST!, {Y0,Y1,Y2,Y3}
 
-	vpop	{T0, T1}	C updated counters
-	vadd.i32	X3, X3, T3
-	vadd.i32	Y3, Y3, T0
-	vadd.i32	Z3, Z3, T1
+	vadd.i32	Z0, Z0, T0
+	vadd.i32	Z1, Z1, T1
+	vadd.i32	Z2, Z2, T2
 
 	vpop	{q4,q5,q6,q7}
 
-	vstmia	DST!, {X0,X1,X2,X3}
-	vstmia	DST!, {Y0,Y1,Y2,Y3}
 	vstm	DST, {Z0,Z1,Z2,Z3}
 	bx	lr
 EPILOGUE(_nettle_chacha_3core)