gcc-4.4-source 4.4.7-1ubuntu2 / usr / src / gcc-4.4 / debian / patches / arm-thumb2-speedup-division.diff

# DP: ARM: speed up division on Thumb-2 (backport from the trunk)

2009-08-06  Paul Brook  <paul@codesourcery.com>

	gcc/
	* config/arm/lib1funcs.asm (ARM_DIV_BODY): Add Thumb-2 implementation.
	(udivsi3, aeabi_uidivmod, divsi3, aeabi_idivmod): Only use Thumb-1
	implementation on ARMv6-M.

---
 src/gcc/config/arm/lib1funcs.asm |   63 +++++++++++++++++++++++++++++++++------
 1 file changed, 54 insertions(+), 9 deletions(-)

--- a/src/gcc/config/arm/lib1funcs.asm
+++ b/src/gcc/config/arm/lib1funcs.asm
@@ -436,10 +436,31 @@ pc		.req	r15
 /* ------------------------------------------------------------------------ */	
 .macro ARM_DIV_BODY dividend, divisor, result, curbit
 
 #if __ARM_ARCH__ >= 5 && ! defined (__OPTIMIZE_SIZE__)
 
+#if defined (__thumb2__)
+	clz	\curbit, \dividend
+	clz	\result, \divisor
+	sub	\curbit, \result, \curbit
+	rsb	\curbit, \curbit, #31
+	adr	\result, 1f
+	add	\curbit, \result, \curbit, lsl #4
+	mov	\result, #0
+	mov	pc, \curbit
+.p2align 3
+1:
+	.set	shift, 32
+	.rept	32
+	.set	shift, shift - 1
+	cmp.w	\dividend, \divisor, lsl #shift
+	nop.n
+	adc.w	\result, \result, \result
+	it	cs
+	subcs.w	\dividend, \dividend, \divisor, lsl #shift
+	.endr
+#else
 	clz	\curbit, \dividend
 	clz	\result, \divisor
 	sub	\curbit, \result, \curbit
 	rsbs	\curbit, \curbit, #31
 	addne	\curbit, \curbit, \curbit, lsl #1
@@ -451,10 +472,11 @@ pc		.req	r15
 	.set	shift, shift - 1
 	cmp	\dividend, \divisor, lsl #shift
 	adc	\result, \result, \result
 	subcs	\dividend, \dividend, \divisor, lsl #shift
 	.endr
+#endif
 
 #else /* __ARM_ARCH__ < 5 || defined (__OPTIMIZE_SIZE__) */
 #if __ARM_ARCH__ >= 5
 
 	clz	\curbit, \divisor
@@ -498,22 +520,27 @@ pc		.req	r15
 
 #endif /* __ARM_ARCH__ < 5 */
 
 	@ Division loop
 1:	cmp	\dividend, \divisor
+	do_it	hs, t
 	subhs	\dividend, \dividend, \divisor
 	orrhs	\result,   \result,   \curbit
 	cmp	\dividend, \divisor,  lsr #1
+	do_it	hs, t
 	subhs	\dividend, \dividend, \divisor, lsr #1
 	orrhs	\result,   \result,   \curbit,  lsr #1
 	cmp	\dividend, \divisor,  lsr #2
+	do_it	hs, t
 	subhs	\dividend, \dividend, \divisor, lsr #2
 	orrhs	\result,   \result,   \curbit,  lsr #2
 	cmp	\dividend, \divisor,  lsr #3
+	do_it	hs, t
 	subhs	\dividend, \dividend, \divisor, lsr #3
 	orrhs	\result,   \result,   \curbit,  lsr #3
 	cmp	\dividend, #0			@ Early termination?
+	do_it	hs, t
 	movnes	\curbit,   \curbit,  lsr #4	@ No, any more bits to do?
 	movne	\divisor,  \divisor, lsr #4
 	bne	1b
 
 #endif /* __ARM_ARCH__ < 5 || defined (__OPTIMIZE_SIZE__) */
@@ -798,15 +825,15 @@ LSYM(Lgot_result):
 /* ------------------------------------------------------------------------ */
 /*		Start of the Real Functions				    */
 /* ------------------------------------------------------------------------ */
 #ifdef L_udivsi3
 
+#if defined(__ARM_ARCH_6M__)
+
 	FUNC_START udivsi3
 	FUNC_ALIAS aeabi_uidiv udivsi3
 
-#ifdef __thumb__
-
 	cmp	divisor, #0
 	beq	LSYM(Ldiv0)
 	mov	curbit, #1
 	mov	result, #0
 	
@@ -818,13 +845,17 @@ LSYM(Lgot_result):
 	
 	mov	r0, result
 	pop	{ work }
 	RET
 
-#else /* ARM version.  */
+#else /* ARM version/Thumb-2.  */
+
+	ARM_FUNC_START udivsi3
+	ARM_FUNC_ALIAS aeabi_uidiv udivsi3
 
 	subs	r2, r1, #1
+	do_it	eq
 	RETc(eq)
 	bcc	LSYM(Ldiv0)
 	cmp	r0, r1
 	bls	11f
 	tst	r1, r2
@@ -833,11 +864,12 @@ LSYM(Lgot_result):
 	ARM_DIV_BODY r0, r1, r2, r3
 	
 	mov	r0, r2
 	RET	
 
-11:	moveq	r0, #1
+11:	do_it	eq, e
+	moveq	r0, #1
 	movne	r0, #0
 	RET
 
 12:	ARM_DIV2_ORDER r1, r2
 
@@ -846,19 +878,20 @@ LSYM(Lgot_result):
 
 #endif /* ARM version */
 
 	DIV_FUNC_END udivsi3
 
+#if defined(__ARM_ARCH_6M__)
 FUNC_START aeabi_uidivmod
-#ifdef __thumb__
 	push	{r0, r1, lr}
 	bl	SYM(__udivsi3)
 	POP	{r1, r2, r3}
 	mul	r2, r0
 	sub	r1, r1, r2
 	bx	r3
 #else
+ARM_FUNC_START aeabi_uidivmod
 	stmfd	sp!, { r0, r1, lr }
 	bl	SYM(__udivsi3)
 	ldmfd	sp!, { r1, r2, lr }
 	mul	r3, r2, r0
 	sub	r1, r1, r3
@@ -909,14 +942,15 @@ LSYM(Lover10):
 
 #endif /* L_umodsi3 */
 /* ------------------------------------------------------------------------ */
 #ifdef L_divsi3
 
+#if defined(__ARM_ARCH_6M__)
+
 	FUNC_START divsi3	
 	FUNC_ALIAS aeabi_idiv divsi3
 
-#ifdef __thumb__
 	cmp	divisor, #0
 	beq	LSYM(Ldiv0)
 	
 	push	{ work }
 	mov	work, dividend
@@ -944,60 +978,71 @@ LSYM(Lover11):
 	neg	r0, r0
 LSYM(Lover12):
 	pop	{ work }
 	RET
 
-#else /* ARM version.  */
+#else /* ARM/Thumb-2 version.  */
 	
+	ARM_FUNC_START divsi3
+	ARM_FUNC_ALIAS aeabi_idiv divsi3
+
 	cmp	r1, #0
 	eor	ip, r0, r1			@ save the sign of the result.
 	beq	LSYM(Ldiv0)
+	do_it	mi
 	rsbmi	r1, r1, #0			@ loops below use unsigned.
 	subs	r2, r1, #1			@ division by 1 or -1 ?
 	beq	10f
 	movs	r3, r0
+	do_it	mi
 	rsbmi	r3, r0, #0			@ positive dividend value
 	cmp	r3, r1
 	bls	11f
 	tst	r1, r2				@ divisor is power of 2 ?
 	beq	12f
 
 	ARM_DIV_BODY r3, r1, r0, r2
 	
 	cmp	ip, #0
+	do_it	mi
 	rsbmi	r0, r0, #0
 	RET	
 
 10:	teq	ip, r0				@ same sign ?
+	do_it	mi
 	rsbmi	r0, r0, #0
 	RET	
 
-11:	movlo	r0, #0
+11:	do_it	lo
+	movlo	r0, #0
+	do_it	eq,t
 	moveq	r0, ip, asr #31
 	orreq	r0, r0, #1
 	RET
 
 12:	ARM_DIV2_ORDER r1, r2
 
 	cmp	ip, #0
 	mov	r0, r3, lsr r2
+	do_it	mi
 	rsbmi	r0, r0, #0
 	RET
 
 #endif /* ARM version */
 	
 	DIV_FUNC_END divsi3
 
+#if defined(__ARM_ARCH_6M__)
 FUNC_START aeabi_idivmod
-#ifdef __thumb__
 	push	{r0, r1, lr}
 	bl	SYM(__divsi3)
 	POP	{r1, r2, r3}
 	mul	r2, r0
 	sub	r1, r1, r2
 	bx	r3
 #else
+ARM_FUNC_START aeabi_idivmod
 	stmfd	sp!, { r0, r1, lr }
 	bl	SYM(__divsi3)
 	ldmfd	sp!, { r1, r2, lr }
 	mul	r3, r2, r0
 	sub	r1, r1, r3