Initial commit: Go 1.23 release state

src/runtime/memclr_arm64.s

@@ -0,0 +1,182 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "textflag.h"
+
+// See memclrNoHeapPointers Go doc for important implementation constraints.
+
+// func memclrNoHeapPointers(ptr unsafe.Pointer, n uintptr)
+// Also called from assembly in sys_windows_arm64.s without g (but using Go stack convention).
+TEXT runtime·memclrNoHeapPointers<ABIInternal>(SB),NOSPLIT,$0-16
+	CMP	$16, R1
+	// If n is equal to 16 bytes, use zero_exact_16 to zero
+	BEQ	zero_exact_16
+
+	// If n is greater than 16 bytes, use zero_by_16 to zero
+	BHI	zero_by_16
+
+	// n is less than 16 bytes
+	ADD	R1, R0, R7
+	TBZ	$3, R1, less_than_8
+	MOVD	ZR, (R0)
+	MOVD	ZR, -8(R7)
+	RET
+
+less_than_8:
+	TBZ	$2, R1, less_than_4
+	MOVW	ZR, (R0)
+	MOVW	ZR, -4(R7)
+	RET
+
+less_than_4:
+	CBZ	R1, ending
+	MOVB	ZR, (R0)
+	TBZ	$1, R1, ending
+	MOVH	ZR, -2(R7)
+
+ending:
+	RET
+
+zero_exact_16:
+	// n is exactly 16 bytes
+	STP	(ZR, ZR), (R0)
+	RET
+
+zero_by_16:
+	// n greater than 16 bytes, check if the start address is aligned
+	NEG	R0, R4
+	ANDS	$15, R4, R4
+	// Try zeroing using zva if the start address is aligned with 16
+	BEQ	try_zva
+
+	// Non-aligned store
+	STP	(ZR, ZR), (R0)
+	// Make the destination aligned
+	SUB	R4, R1, R1
+	ADD	R4, R0, R0
+	B	try_zva
+
+tail_maybe_long:
+	CMP	$64, R1
+	BHS	no_zva
+
+tail63:
+	ANDS	$48, R1, R3
+	BEQ	last16
+	CMPW	$32, R3
+	BEQ	last48
+	BLT	last32
+	STP.P	(ZR, ZR), 16(R0)
+last48:
+	STP.P	(ZR, ZR), 16(R0)
+last32:
+	STP.P	(ZR, ZR), 16(R0)
+	// The last store length is at most 16, so it is safe to use
+	// stp to write last 16 bytes
+last16:
+	ANDS	$15, R1, R1
+	CBZ	R1, last_end
+	ADD	R1, R0, R0
+	STP	(ZR, ZR), -16(R0)
+last_end:
+	RET
+
+no_zva:
+	SUB	$16, R0, R0
+	SUB	$64, R1, R1
+
+loop_64:
+	STP	(ZR, ZR), 16(R0)
+	STP	(ZR, ZR), 32(R0)
+	STP	(ZR, ZR), 48(R0)
+	STP.W	(ZR, ZR), 64(R0)
+	SUBS	$64, R1, R1
+	BGE	loop_64
+	ANDS	$63, R1, ZR
+	ADD	$16, R0, R0
+	BNE	tail63
+	RET
+
+try_zva:
+	// Try using the ZVA feature to zero entire cache lines
+	// It is not meaningful to use ZVA if the block size is less than 64,
+	// so make sure that n is greater than or equal to 64
+	CMP	$63, R1
+	BLE	tail63
+
+	CMP	$128, R1
+	// Ensure n is at least 128 bytes, so that there is enough to copy after
+	// alignment.
+	BLT	no_zva
+	// Check if ZVA is allowed from user code, and if so get the block size
+	MOVW	block_size<>(SB), R5
+	TBNZ	$31, R5, no_zva
+	CBNZ	R5, zero_by_line
+	// DCZID_EL0 bit assignments
+	// [63:5] Reserved
+	// [4]    DZP, if bit set DC ZVA instruction is prohibited, else permitted
+	// [3:0]  log2 of the block size in words, eg. if it returns 0x4 then block size is 16 words
+	MRS	DCZID_EL0, R3
+	TBZ	$4, R3, init
+	// ZVA not available
+	MOVW	$~0, R5
+	MOVW	R5, block_size<>(SB)
+	B	no_zva
+
+init:
+	MOVW	$4, R9
+	ANDW	$15, R3, R5
+	LSLW	R5, R9, R5
+	MOVW	R5, block_size<>(SB)
+
+	ANDS	$63, R5, R9
+	// Block size is less than 64.
+	BNE	no_zva
+
+zero_by_line:
+	CMP	R5, R1
+	// Not enough memory to reach alignment
+	BLO	no_zva
+	SUB	$1, R5, R6
+	NEG	R0, R4
+	ANDS	R6, R4, R4
+	// Already aligned
+	BEQ	aligned
+
+	// check there is enough to copy after alignment
+	SUB	R4, R1, R3
+
+	// Check that the remaining length to ZVA after alignment
+	// is greater than 64.
+	CMP	$64, R3
+	CCMP	GE, R3, R5, $10  // condition code GE, NZCV=0b1010
+	BLT	no_zva
+
+	// We now have at least 64 bytes to zero, update n
+	MOVD	R3, R1
+
+loop_zva_prolog:
+	STP	(ZR, ZR), (R0)
+	STP	(ZR, ZR), 16(R0)
+	STP	(ZR, ZR), 32(R0)
+	SUBS	$64, R4, R4
+	STP	(ZR, ZR), 48(R0)
+	ADD	$64, R0, R0
+	BGE	loop_zva_prolog
+
+	ADD	R4, R0, R0
+
+aligned:
+	SUB	R5, R1, R1
+
+loop_zva:
+	WORD	$0xd50b7420 // DC ZVA, R0
+	ADD	R5, R0, R0
+	SUBS	R5, R1, R1
+	BHS	loop_zva
+	ANDS	R6, R1, R1
+	BNE	tail_maybe_long
+	RET
+
+GLOBL block_size<>(SB), NOPTR, $8