ppc: Reduce number of registers used for ecc_secp256r1_redc.

1 files changed, 26 insertions, 42 deletions

diff --git a/powerpc64/ecc-secp256r1-redc.asm b/powerpc64/ecc-secp256r1-redc.asm
index 8012a61e..e61a20cb 100644
--- a/powerpc64/ecc-secp256r1-redc.asm
+++ b/powerpc64/ecc-secp256r1-redc.asm
@@ -34,42 +34,36 @@ ifelse(`
 
 C Register usage:
 
-define(`SP', `r1')
-
 define(`RP', `r4')
 define(`XP', `r5')
 
 define(`F0', `r3')
 define(`F1', `r6')
 define(`F2', `r7')
-define(`F3', `r8')
+define(`T', `r8')
 
 define(`U0', `r9')
 define(`U1', `r10')
 define(`U2', `r11')
 define(`U3', `r12')
-define(`U4', `r14')
-define(`U5', `r15')
-define(`U6', `r16')
-define(`U7', `r17')
 
 	.file "ecc-secp256r1-redc.asm"
 
-C FOLD(x), sets (F3,F2,F1,F0)  <-- [(x << 192) - (x << 160) + (x << 128) + (x <<32)]
+C FOLD(x), sets (x,F2,F1,F0)  <-- [(x << 192) - (x << 160) + (x << 128) + (x <<32)]
 define(`FOLD', `
 	sldi	F0, $1, 32
 	srdi	F1, $1, 32
 	subfc	F2, F0, $1
-	subfe	F3, F1, $1
+	subfe	$1, F1, $1
 ')
 
-C FOLDC(x), sets (F3,F2,F1,F0)  <-- [((x+c) << 192) - (x << 160) + (x << 128) + (x <<32)]
+C FOLDC(x), sets (x,F2,F1,F0)  <-- [((x+c) << 192) - (x << 160) + (x << 128) + (x <<32)]
 define(`FOLDC', `
 	sldi	F0, $1, 32
 	srdi	F1, $1, 32
-	addze	F3, $1
+	addze	T, $1
 	subfc	F2, F0, $1
-	subfe	F3, F1, F3
+	subfe	$1, F1, T
 ')
 
 	C void ecc_secp256r1_redc (const struct ecc_modulo *p, mp_limb_t *rp, mp_limb_t *xp)
@@ -77,43 +71,38 @@ define(`FOLDC', `
 define(`FUNC_ALIGN', `5')
 PROLOGUE(_nettle_ecc_secp256r1_redc)
 
-	std	U4,-32(SP)
-	std	U5,-24(SP)
-	std	U6,-16(SP)
-	std	U7,-8(SP)
-
 	ld	U0, 0(XP)
 	ld	U1, 8(XP)
 	ld	U2, 16(XP)
 	ld	U3, 24(XP)
-	ld	U4, 32(XP)
-	ld	U5, 40(XP)
-	ld	U6, 48(XP)
-	ld	U7, 56(XP)
 
 	FOLD(U0)
+	ld	T, 32(XP)
 	addc	U1, F0, U1
 	adde	U2, F1, U2
 	adde	U3, F2, U3
-	adde	U4, F3, U4
+	adde	U0, U0, T
 
 	FOLDC(U1)
+	ld	T, 40(XP)
 	addc	U2, F0, U2
 	adde	U3, F1, U3
-	adde	U4, F2, U4
-	adde	U5, F3, U5
+	adde	U0, F2, U0
+	adde	U1, U1, T
 
 	FOLDC(U2)
+	ld	T, 48(XP)
 	addc	U3, F0, U3
-	adde	U4, F1, U4
-	adde	U5, F2, U5
-	adde	U6, F3, U6
+	adde	U0, F1, U0
+	adde	U1, F2, U1
+	adde	U2, U2, T
 
 	FOLDC(U3)
-	addc	U4, F0, U4
-	adde	U5, F1, U5
-	adde	U6, F2, U6
-	adde	U7, F3, U7
+	ld	T, 56(XP)
+	addc	U0, F0, U0
+	adde	U1, F1, U1
+	adde	U2, F2, U2
+	adde	U3, U3, T
 
 	C If carry, we need to add in
 	C 2^256 - p = <0xfffffffe, 0xff..ff, 0xffffffff00000000, 1>
@@ -121,24 +110,19 @@ PROLOGUE(_nettle_ecc_secp256r1_redc)
 	addze	F0, F0
 	neg	F2, F0
 	sldi	F1, F2, 32
-	srdi	F3, F2, 32
+	srdi	T, F2, 32
 	li	XP, -2
-	and	F3, F3, XP
+	and	T, T, XP
 
-	addc	U0, F0, U4
-	adde	U1, F1, U5
-	adde	U2, F2, U6
-	adde	U3, F3, U7
+	addc	U0, F0, U0
+	adde	U1, F1, U1
+	adde	U2, F2, U2
+	adde	U3, T, U3
 
 	std	U0, 0(RP)
 	std	U1, 8(RP)
 	std	U2, 16(RP)
 	std	U3, 24(RP)
 
-	ld	U4,-32(SP)
-	ld	U5,-24(SP)
-	ld	U6,-16(SP)
-	ld	U7,-8(SP)
-
 	blr
 EPILOGUE(_nettle_ecc_secp256r1_redc)