crypto/bn/asm/s390x.S: drop redundant instructions.

crypto/bn/asm/s390x.S

-.ident "s390x.S, version 1.0"
+.ident "s390x.S, version 1.1"
 // ====================================================================
 // Written by Andy Polyakov <appro@fy.chalmers.se> for the OpenSSL
 // project.
@@ -24,67 +24,67 @@ bn_mul_add_words:
 	bler	%r14		// if (len<=0) return 0;
 
 	stmg	%r6,%r10,48(%r15)
+	lghi	%r10,3
 	lghi	%r8,0		// carry = 0
-	srag	%r10,%r4,2	// cnt=len/4
-	jz	.Loop1_madd
+	nr	%r10,%r4	// len%4
+	sra	%r4,2		// cnt=len/4
+	jz	.Loop1_madd	// carry is incidentally cleared if branch taken
+	algr	zero,zero	// clear carry
 
 .Loop4_madd:
 	lg	%r7,0(%r2,%r3)	// ap[i]
 	mlgr	%r6,%r5		// *=w
-	algr	%r7,%r8		// +=carry
+	alcgr	%r7,%r8		// +=carry
 	alcgr	%r6,zero
 	alg	%r7,0(%r2,%r1)	// +=rp[i]
-	alcgr	%r6,zero
 	stg	%r7,0(%r2,%r1)	// rp[i]=
 
 	lg	%r9,8(%r2,%r3)
 	mlgr	%r8,%r5
-	algr	%r9,%r6
+	alcgr	%r9,%r6
 	alcgr	%r8,zero
 	alg	%r9,8(%r2,%r1)
-	alcgr	%r8,zero
 	stg	%r9,8(%r2,%r1)
 
 	lg	%r7,16(%r2,%r3)
 	mlgr	%r6,%r5
-	algr	%r7,%r8
+	alcgr	%r7,%r8
 	alcgr	%r6,zero
 	alg	%r7,16(%r2,%r1)
-	alcgr	%r6,zero
 	stg	%r7,16(%r2,%r1)
 
 	lg	%r9,24(%r2,%r3)
 	mlgr	%r8,%r5
-	algr	%r9,%r6
+	alcgr	%r9,%r6
 	alcgr	%r8,zero
 	alg	%r9,24(%r2,%r1)
-	alcgr	%r8,zero
 	stg	%r9,24(%r2,%r1)
 
 	la	%r2,32(%r2)	// i+=4
-	brct	%r10,.Loop4_madd
+	brct	%r4,.Loop4_madd
 
-	lghi	%r10,3
-	nr	%r4,%r10	// cnt=len%4
-	jz	.Lend_madd
+	la	%r10,1(%r10)		// see if len%4 is zero ...
+	brct	%r10,.Loop1_madd	// without touching condition code:-)
+
+.Lend_madd:
+	alcgr	%r8,zero	// collect carry bit
+	lgr	%r2,%r8
+	lmg	%r6,%r10,48(%r15)
+	br	%r14
 
 .Loop1_madd:
 	lg	%r7,0(%r2,%r3)	// ap[i]
 	mlgr	%r6,%r5		// *=w
-	algr	%r7,%r8		// +=carry
+	alcgr	%r7,%r8		// +=carry
 	alcgr	%r6,zero
 	alg	%r7,0(%r2,%r1)	// +=rp[i]
-	alcgr	%r6,zero
 	stg	%r7,0(%r2,%r1)	// rp[i]=
 
 	lgr	%r8,%r6
 	la	%r2,8(%r2)	// i++
-	brct	%r4,.Loop1_madd
+	brct	%r10,.Loop1_madd
 
-.Lend_madd:
-	lgr	%r2,%r8
-	lmg	%r6,%r10,48(%r15)
-	br	%r14
+	j	.Lend_madd
 .size	bn_mul_add_words,.-bn_mul_add_words
 
 // BN_ULONG bn_mul_words(BN_ULONG *r2,BN_ULONG *r3,int r4,BN_ULONG r5);
@@ -99,57 +99,57 @@ bn_mul_words:
 	bler	%r14		// if (len<=0) return 0;
 
 	stmg	%r6,%r10,48(%r15)
+	lghi	%r10,3
 	lghi	%r8,0		// carry = 0
-	srag	%r10,%r4,2	// cnt=len/4
-	jz	.Loop1_mul
+	nr	%r10,%r4	// len%4
+	sra	%r4,2		// cnt=len/4
+	jz	.Loop1_mul	// carry is incidentally cleared if branch taken
+	algr	zero,zero	// clear carry
 
 .Loop4_mul:
 	lg	%r7,0(%r2,%r3)	// ap[i]
 	mlgr	%r6,%r5		// *=w
-	algr	%r7,%r8		// +=carry
-	alcgr	%r6,zero
+	alcgr	%r7,%r8		// +=carry
 	stg	%r7,0(%r2,%r1)	// rp[i]=
 
 	lg	%r9,8(%r2,%r3)
 	mlgr	%r8,%r5
-	algr	%r9,%r6
-	alcgr	%r8,zero
+	alcgr	%r9,%r6
 	stg	%r9,8(%r2,%r1)
 
 	lg	%r7,16(%r2,%r3)
 	mlgr	%r6,%r5
-	algr	%r7,%r8
-	alcgr	%r6,zero
+	alcgr	%r7,%r8
 	stg	%r7,16(%r2,%r1)
 
 	lg	%r9,24(%r2,%r3)
 	mlgr	%r8,%r5
-	algr	%r9,%r6
-	alcgr	%r8,zero
+	alcgr	%r9,%r6
 	stg	%r9,24(%r2,%r1)
 
 	la	%r2,32(%r2)	// i+=4
-	brct	%r10,.Loop4_mul
+	brct	%r4,.Loop4_mul
 
-	lghi	%r10,3
-	nr	%r4,%r10	// cnt=len%4
-	jz	.Lend_mul
+	la	%r10,1(%r10)		// see if len%4 is zero ...
+	brct	%r10,.Loop1_madd	// without touching condition code:-)
+
+.Lend_mul:
+	alcgr	%r8,zero	// collect carry bit
+	lgr	%r2,%r8
+	lmg	%r6,%r10,48(%r15)
+	br	%r14
 
 .Loop1_mul:
 	lg	%r7,0(%r2,%r3)	// ap[i]
 	mlgr	%r6,%r5		// *=w
-	algr	%r7,%r8		// +=carry
-	alcgr	%r6,zero
+	alcgr	%r7,%r8		// +=carry
 	stg	%r7,0(%r2,%r1)	// rp[i]=
 
 	lgr	%r8,%r6
 	la	%r2,8(%r2)	// i++
-	brct	%r4,.Loop1_mul
+	brct	%r10,.Loop1_mul
 
-.Lend_mul:
-	lgr	%r2,%r8
-	lmg	%r6,%r10,48(%r15)
-	br	%r14
+	j	.Lend_mul
 .size	bn_mul_words,.-bn_mul_words
 
 // void bn_sqr_words(BN_ULONG *r2,BN_ULONG *r2,int r4)