forked from OSchip/llvm-project
37 lines
1.0 KiB
ArmAsm
37 lines
1.0 KiB
ArmAsm
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//===-------- modsi3.S - Implement modsi3 ---------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#include "../assembly.h"
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//
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// extern int32_t __modsi3(int32_t a, int32_t b);
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//
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// Returns the remainder when dividing two 32-bit signed integers.
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// Conceptually, the function is: { return a - (a / b) * b; }
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// But if you write that in C, llvm compiles it to a call to __modsi3...
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//
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.align 2
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DEFINE_COMPILERRT_FUNCTION(__modsi3)
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push {r4, r5, r7, lr}
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add r7, sp, #8 // set stack frame
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mov r5, r0 // save a
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mov r4, r1 // save b
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bl ___divsi3 // compute a/b
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#if __ARM_ARCH_7A__
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mls r0, r4, r0, r5 // mulitple result * b and subtract from a
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#else
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// before armv7, does not have "mls" instruction
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mul r3, r0, r4 // multiple result * b
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sub r0, r5, r3 // a - result
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#endif
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pop {r4, r5, r7, pc}
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