Blame - compiler-rt/lib/builtins/arm/udivsi3.S - toolchain/llvm-project

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Joerg Sonnenberger	dde2700	2014-01-30 18:41:32 +0000	[diff] [blame]	1	/*===-- udivsi3.S - 32-bit unsigned integer divide ------------------------===//
Stephen Canon	5abb5c1	2011-03-18 16:35:02 +0000	[diff] [blame]	2	*
				3	* The LLVM Compiler Infrastructure
				4	*
				5	* This file is dual licensed under the MIT and the University of Illinois Open
				6	* Source Licenses. See LICENSE.TXT for details.
				7	*
				8	*===----------------------------------------------------------------------===//
				9	*
Joerg Sonnenberger	59611a8	2014-01-24 13:43:35 +0000	[diff] [blame]	10	* This file implements the __udivsi3 (32-bit unsigned integer divide)
				11	* function for the ARM 32-bit architecture.
Stephen Canon	5abb5c1	2011-03-18 16:35:02 +0000	[diff] [blame]	12	*
				13	===----------------------------------------------------------------------===/
				14
				15	#include "../assembly.h"
				16
Joerg Sonnenberger	59611a8	2014-01-24 13:43:35 +0000	[diff] [blame]	17	.syntax unified
Joerg Sonnenberger	59611a8	2014-01-24 13:43:35 +0000	[diff] [blame]	18	.text
Saleem Abdulrasool	8f2efc3	2014-06-16 16:36:25 +0000	[diff] [blame]	19
Joerg Sonnenberger	9720fcf	2014-07-20 20:53:37 +0000	[diff] [blame]	20	#if __ARM_ARCH_ISA_THUMB == 2
				21	.thumb
				22	#endif
				23
Joerg Sonnenberger	59611a8	2014-01-24 13:43:35 +0000	[diff] [blame]	24	.p2align 2
Anton Korobeynikov	75e3c19	2011-04-19 17:51:24 +0000	[diff] [blame]	25	DEFINE_AEABI_FUNCTION_ALIAS(__aeabi_uidiv, __udivsi3)
Saleem Abdulrasool	a0d6597	2014-08-09 20:17:43 +0000	[diff] [blame]	26
				27	@ unsigned int __udivsi3(unsigned int divident, unsigned int divisor)
				28	@ Calculate and return the quotient of the (unsigned) division.
				29
Saleem Abdulrasool	48d4e4d	2014-10-07 02:39:13 +0000	[diff] [blame]	30	#if __ARM_ARCH_ISA_THUMB == 2
Steven Wu	84610ba	2014-10-04 00:18:59 +0000	[diff] [blame]	31	DEFINE_COMPILERRT_THUMB_FUNCTION(__udivsi3)
Saleem Abdulrasool	48d4e4d	2014-10-07 02:39:13 +0000	[diff] [blame]	32	#else
				33	DEFINE_COMPILERRT_FUNCTION(__udivsi3)
				34	#endif
Stephen Hines	7633afc	2013-10-25 06:26:44 +0000	[diff] [blame]	35	#if __ARM_ARCH_EXT_IDIV__
Joerg Sonnenberger	59611a8	2014-01-24 13:43:35 +0000	[diff] [blame]	36	tst r1, r1
				37	beq LOCAL_LABEL(divby0)
Saleem Abdulrasool	6063983	2014-08-09 20:17:37 +0000	[diff] [blame]	38	udiv r0, r0, r1
Bob Wilson	a4cefbd	2012-09-29 23:37:01 +0000	[diff] [blame]	39	bx lr
Bob Wilson	a4cefbd	2012-09-29 23:37:01 +0000	[diff] [blame]	40	#else
Joerg Sonnenberger	59611a8	2014-01-24 13:43:35 +0000	[diff] [blame]	41	cmp r1, #1
				42	bcc LOCAL_LABEL(divby0)
Joerg Sonnenberger	9720fcf	2014-07-20 20:53:37 +0000	[diff] [blame]	43	IT(eq)
Joerg Sonnenberger	59611a8	2014-01-24 13:43:35 +0000	[diff] [blame]	44	JMPc(lr, eq)
				45	cmp r0, r1
Joerg Sonnenberger	9720fcf	2014-07-20 20:53:37 +0000	[diff] [blame]	46	ITT(cc)
Joerg Sonnenberger	59611a8	2014-01-24 13:43:35 +0000	[diff] [blame]	47	movcc r0, #0
				48	JMPc(lr, cc)
				49	/*
				50	* Implement division using binary long division algorithm.
				51	*
				52	* r0 is the numerator, r1 the denominator.
				53	*
				54	* The code before JMP computes the correct shift I, so that
				55	* r0 and (r1 << I) have the highest bit set in the same position.
				56	* At the time of JMP, ip := .Ldiv0block - 12 * I.
				57	* This depends on the fixed instruction size of block.
Joerg Sonnenberger	9720fcf	2014-07-20 20:53:37 +0000	[diff] [blame]	58	* For ARM mode, this is 12 Bytes, for THUMB mode 14 Bytes.
Joerg Sonnenberger	59611a8	2014-01-24 13:43:35 +0000	[diff] [blame]	59	*
				60	* block(shift) implements the test-and-update-quotient core.
				61	* It assumes (r0 << shift) can be computed without overflow and
				62	* that (r0 << shift) < 2 * r1. The quotient is stored in r3.
				63	*/
Stephen Canon	5abb5c1	2011-03-18 16:35:02 +0000	[diff] [blame]	64
Joerg Sonnenberger	59611a8	2014-01-24 13:43:35 +0000	[diff] [blame]	65	# ifdef __ARM_FEATURE_CLZ
				66	clz ip, r0
				67	clz r3, r1
				68	/* r0 >= r1 implies clz(r0) <= clz(r1), so ip <= r3. */
				69	sub r3, r3, ip
Joerg Sonnenberger	9720fcf	2014-07-20 20:53:37 +0000	[diff] [blame]	70	# if __ARM_ARCH_ISA_THUMB == 2
				71	adr ip, LOCAL_LABEL(div0block) + 1
				72	sub ip, ip, r3, lsl #1
				73	# else
Joerg Sonnenberger	8f6cf70	2014-07-20 20:00:26 +0000	[diff] [blame]	74	adr ip, LOCAL_LABEL(div0block)
Joerg Sonnenberger	9720fcf	2014-07-20 20:53:37 +0000	[diff] [blame]	75	# endif
Joerg Sonnenberger	59611a8	2014-01-24 13:43:35 +0000	[diff] [blame]	76	sub ip, ip, r3, lsl #2
				77	sub ip, ip, r3, lsl #3
				78	mov r3, #0
				79	bx ip
				80	# else
Joerg Sonnenberger	9720fcf	2014-07-20 20:53:37 +0000	[diff] [blame]	81	# if __ARM_ARCH_ISA_THUMB == 2
				82	# error THUMB mode requires CLZ or UDIV
				83	# endif
Joerg Sonnenberger	59611a8	2014-01-24 13:43:35 +0000	[diff] [blame]	84	mov r2, r0
Joerg Sonnenberger	8f6cf70	2014-07-20 20:00:26 +0000	[diff] [blame]	85	adr ip, LOCAL_LABEL(div0block)
Stephen Canon	5abb5c1	2011-03-18 16:35:02 +0000	[diff] [blame]	86
Joerg Sonnenberger	59611a8	2014-01-24 13:43:35 +0000	[diff] [blame]	87	lsr r3, r2, #16
				88	cmp r3, r1
				89	movhs r2, r3
				90	subhs ip, ip, #(16 * 12)
Stephen Canon	5abb5c1	2011-03-18 16:35:02 +0000	[diff] [blame]	91
Joerg Sonnenberger	59611a8	2014-01-24 13:43:35 +0000	[diff] [blame]	92	lsr r3, r2, #8
				93	cmp r3, r1
				94	movhs r2, r3
				95	subhs ip, ip, #(8 * 12)
				96
				97	lsr r3, r2, #4
				98	cmp r3, r1
				99	movhs r2, r3
				100	subhs ip, #(4 * 12)
				101
				102	lsr r3, r2, #2
				103	cmp r3, r1
				104	movhs r2, r3
				105	subhs ip, ip, #(2 * 12)
				106
				107	/* Last block, no need to update r2 or r3. */
				108	cmp r1, r2, lsr #1
				109	subls ip, ip, #(1 * 12)
				110
				111	mov r3, #0
				112
				113	JMP(ip)
				114	# endif
				115
				116	#define IMM #
				117
Saleem Abdulrasool	31306b1	2014-07-27 02:01:15 +0000	[diff] [blame]	118	#define block(shift) \
				119	cmp r0, r1, lsl IMM shift; \
				120	ITT(hs); \
Saleem Abdulrasool	3a2d6a3	2014-07-27 02:01:24 +0000	[diff] [blame]	121	WIDE(addhs) r3, r3, IMM (1 << shift); \
				122	WIDE(subhs) r0, r0, r1, lsl IMM shift
Joerg Sonnenberger	59611a8	2014-01-24 13:43:35 +0000	[diff] [blame]	123
				124	block(31)
				125	block(30)
				126	block(29)
				127	block(28)
				128	block(27)
				129	block(26)
				130	block(25)
				131	block(24)
				132	block(23)
				133	block(22)
				134	block(21)
				135	block(20)
				136	block(19)
				137	block(18)
				138	block(17)
				139	block(16)
				140	block(15)
				141	block(14)
				142	block(13)
				143	block(12)
				144	block(11)
				145	block(10)
				146	block(9)
				147	block(8)
				148	block(7)
				149	block(6)
				150	block(5)
				151	block(4)
				152	block(3)
				153	block(2)
				154	block(1)
Joerg Sonnenberger	8f6cf70	2014-07-20 20:00:26 +0000	[diff] [blame]	155	LOCAL_LABEL(div0block):
Joerg Sonnenberger	59611a8	2014-01-24 13:43:35 +0000	[diff] [blame]	156	block(0)
				157
				158	mov r0, r3
				159	JMP(lr)
				160	#endif /* __ARM_ARCH_EXT_IDIV__ */
				161
				162	LOCAL_LABEL(divby0):
				163	mov r0, #0
				164	#ifdef __ARM_EABI__
				165	b __aeabi_idiv0
				166	#else
				167	JMP(lr)
Bob Wilson	a4cefbd	2012-09-29 23:37:01 +0000	[diff] [blame]	168	#endif
Joerg Sonnenberger	59611a8	2014-01-24 13:43:35 +0000	[diff] [blame]	169
				170	END_COMPILERRT_FUNCTION(__udivsi3)