forked from OSchip/llvm-project
71 lines
2.1 KiB
ArmAsm
71 lines
2.1 KiB
ArmAsm
//===-- 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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