memclr_riscv64.s

     1  // Copyright 2016 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  #include "textflag.h"
     6  
     7  // See memclrNoHeapPointers Go doc for important implementation constraints.
     8  
     9  // void runtime·memclrNoHeapPointers(void*, uintptr)
    10  TEXT runtime·memclrNoHeapPointers<ABIInternal>(SB),NOSPLIT,$0-16
    11  #ifndef GOEXPERIMENT_regabiargs
    12  	MOV	ptr+0(FP), A0
    13  	MOV	n+8(FP), A1
    14  #endif
    15  	ADD	A0, A1, T4
    16  
    17  	// If less than eight bytes, do one byte at a time.
    18  	SLTU	$8, A1, T3
    19  	BNE	T3, ZERO, outcheck
    20  
    21  	// Do one byte at a time until eight-aligned.
    22  	JMP	aligncheck
    23  align:
    24  	MOVB	ZERO, (A0)
    25  	ADD	$1, A0
    26  aligncheck:
    27  	AND	$7, A0, T3
    28  	BNE	T3, ZERO, align
    29  
    30  	// Do eight bytes at a time as long as there is room.
    31  	ADD	$-7, T4, T5
    32  	JMP	wordscheck
    33  words:
    34  	MOV	ZERO, (A0)
    35  	ADD	$8, A0
    36  wordscheck:
    37  	SLTU	T5, A0, T3
    38  	BNE	T3, ZERO, words
    39  
    40  	JMP	outcheck
    41  out:
    42  	MOVB	ZERO, (A0)
    43  	ADD	$1, A0
    44  outcheck:
    45  	BNE	A0, T4, out
    46  
    47  done:
    48  	RET
    49
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