llvm-project

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//===-- divmodsi4.S - 32-bit signed integer divide and modulus ------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the __divmodsi4 (32-bit signed integer divide and
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// modulus) function for the ARM architecture.  A naive digit-by-digit
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// computation is employed for simplicity.
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//
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//===----------------------------------------------------------------------===//
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#include "../assembly.h"
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#define ESTABLISH_FRAME    \
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    push   {r4-r7, lr}   ;\
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    add     r7,     sp, #12
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#define CLEAR_FRAME_AND_RETURN \
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    pop    {r4-r7, pc}
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	.syntax unified
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	.text
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  DEFINE_CODE_STATE
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@ int __divmodsi4(int divident, int divisor, int *remainder)
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@   Calculate the quotient and remainder of the (signed) division.  The return
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@   value is the quotient, the remainder is placed in the variable.
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	.p2align 3
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DEFINE_COMPILERRT_FUNCTION(__divmodsi4)
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#if __ARM_ARCH_EXT_IDIV__
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	tst     r1, r1
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	beq     LOCAL_LABEL(divzero)
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	mov 	r3, r0
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	sdiv	r0, r3, r1
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	mls 	r1, r0, r1, r3
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	str 	r1, [r2]
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	bx  	lr
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LOCAL_LABEL(divzero):
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	mov     r0, #0
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	bx      lr
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#else
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    ESTABLISH_FRAME
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//  Set aside the sign of the quotient and modulus, and the address for the
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//  modulus.
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    eor     r4,     r0, r1
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    mov     r5,     r0
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    mov     r6,     r2
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//  Take the absolute value of a and b via abs(x) = (x^(x >> 31)) - (x >> 31).
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    eor     ip,     r0, r0, asr #31
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    eor     lr,     r1, r1, asr #31
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    sub     r0,     ip, r0, asr #31
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    sub     r1,     lr, r1, asr #31
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//  Unsigned divmod:
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    bl      SYMBOL_NAME(__udivmodsi4)
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//  Apply the sign of quotient and modulus
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    ldr     r1,    [r6]
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    eor     r0,     r0, r4, asr #31
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    eor     r1,     r1, r5, asr #31
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    sub     r0,     r0, r4, asr #31
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    sub     r1,     r1, r5, asr #31
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    str     r1,    [r6]
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    CLEAR_FRAME_AND_RETURN
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#endif
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END_COMPILERRT_FUNCTION(__divmodsi4)
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NO_EXEC_STACK_DIRECTIVE
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