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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-16 19:23:18 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-16 19:23:18 +0000
commit43a123c1ae6613b3efeed291fa552ecd909d3acf (patch)
treefd92518b7024bc74031f78a1cf9e454b65e73665 /src/runtime/memmove_386.s
parentInitial commit. (diff)
downloadgolang-1.20-upstream.tar.xz
golang-1.20-upstream.zip
Adding upstream version 1.20.14.upstream/1.20.14upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/runtime/memmove_386.s')
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diff --git a/src/runtime/memmove_386.s b/src/runtime/memmove_386.s
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+++ b/src/runtime/memmove_386.s
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+// Inferno's libkern/memmove-386.s
+// https://bitbucket.org/inferno-os/inferno-os/src/master/libkern/memmove-386.s
+//
+// Copyright © 1994-1999 Lucent Technologies Inc. All rights reserved.
+// Revisions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com). All rights reserved.
+// Portions Copyright 2009 The Go Authors. All rights reserved.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+//go:build !plan9
+
+#include "go_asm.h"
+#include "textflag.h"
+
+// See memmove Go doc for important implementation constraints.
+
+// func memmove(to, from unsafe.Pointer, n uintptr)
+TEXT runtime·memmove(SB), NOSPLIT, $0-12
+ MOVL to+0(FP), DI
+ MOVL from+4(FP), SI
+ MOVL n+8(FP), BX
+
+ // REP instructions have a high startup cost, so we handle small sizes
+ // with some straightline code. The REP MOVSL instruction is really fast
+ // for large sizes. The cutover is approximately 1K. We implement up to
+ // 128 because that is the maximum SSE register load (loading all data
+ // into registers lets us ignore copy direction).
+tail:
+ // BSR+branch table make almost all memmove/memclr benchmarks worse. Not worth doing.
+ TESTL BX, BX
+ JEQ move_0
+ CMPL BX, $2
+ JBE move_1or2
+ CMPL BX, $4
+ JB move_3
+ JE move_4
+ CMPL BX, $8
+ JBE move_5through8
+ CMPL BX, $16
+ JBE move_9through16
+#ifdef GO386_softfloat
+ JMP nosse2
+#endif
+ CMPL BX, $32
+ JBE move_17through32
+ CMPL BX, $64
+ JBE move_33through64
+ CMPL BX, $128
+ JBE move_65through128
+
+nosse2:
+/*
+ * check and set for backwards
+ */
+ CMPL SI, DI
+ JLS back
+
+/*
+ * forward copy loop
+ */
+forward:
+ // If REP MOVSB isn't fast, don't use it
+ CMPB internal∕cpu·X86+const_offsetX86HasERMS(SB), $1 // enhanced REP MOVSB/STOSB
+ JNE fwdBy4
+
+ // Check alignment
+ MOVL SI, AX
+ ORL DI, AX
+ TESTL $3, AX
+ JEQ fwdBy4
+
+ // Do 1 byte at a time
+ MOVL BX, CX
+ REP; MOVSB
+ RET
+
+fwdBy4:
+ // Do 4 bytes at a time
+ MOVL BX, CX
+ SHRL $2, CX
+ ANDL $3, BX
+ REP; MOVSL
+ JMP tail
+
+/*
+ * check overlap
+ */
+back:
+ MOVL SI, CX
+ ADDL BX, CX
+ CMPL CX, DI
+ JLS forward
+/*
+ * whole thing backwards has
+ * adjusted addresses
+ */
+
+ ADDL BX, DI
+ ADDL BX, SI
+ STD
+
+/*
+ * copy
+ */
+ MOVL BX, CX
+ SHRL $2, CX
+ ANDL $3, BX
+
+ SUBL $4, DI
+ SUBL $4, SI
+ REP; MOVSL
+
+ CLD
+ ADDL $4, DI
+ ADDL $4, SI
+ SUBL BX, DI
+ SUBL BX, SI
+ JMP tail
+
+move_1or2:
+ MOVB (SI), AX
+ MOVB -1(SI)(BX*1), CX
+ MOVB AX, (DI)
+ MOVB CX, -1(DI)(BX*1)
+ RET
+move_0:
+ RET
+move_3:
+ MOVW (SI), AX
+ MOVB 2(SI), CX
+ MOVW AX, (DI)
+ MOVB CX, 2(DI)
+ RET
+move_4:
+ // We need a separate case for 4 to make sure we write pointers atomically.
+ MOVL (SI), AX
+ MOVL AX, (DI)
+ RET
+move_5through8:
+ MOVL (SI), AX
+ MOVL -4(SI)(BX*1), CX
+ MOVL AX, (DI)
+ MOVL CX, -4(DI)(BX*1)
+ RET
+move_9through16:
+ MOVL (SI), AX
+ MOVL 4(SI), CX
+ MOVL -8(SI)(BX*1), DX
+ MOVL -4(SI)(BX*1), BP
+ MOVL AX, (DI)
+ MOVL CX, 4(DI)
+ MOVL DX, -8(DI)(BX*1)
+ MOVL BP, -4(DI)(BX*1)
+ RET
+move_17through32:
+ MOVOU (SI), X0
+ MOVOU -16(SI)(BX*1), X1
+ MOVOU X0, (DI)
+ MOVOU X1, -16(DI)(BX*1)
+ RET
+move_33through64:
+ MOVOU (SI), X0
+ MOVOU 16(SI), X1
+ MOVOU -32(SI)(BX*1), X2
+ MOVOU -16(SI)(BX*1), X3
+ MOVOU X0, (DI)
+ MOVOU X1, 16(DI)
+ MOVOU X2, -32(DI)(BX*1)
+ MOVOU X3, -16(DI)(BX*1)
+ RET
+move_65through128:
+ MOVOU (SI), X0
+ MOVOU 16(SI), X1
+ MOVOU 32(SI), X2
+ MOVOU 48(SI), X3
+ MOVOU -64(SI)(BX*1), X4
+ MOVOU -48(SI)(BX*1), X5
+ MOVOU -32(SI)(BX*1), X6
+ MOVOU -16(SI)(BX*1), X7
+ MOVOU X0, (DI)
+ MOVOU X1, 16(DI)
+ MOVOU X2, 32(DI)
+ MOVOU X3, 48(DI)
+ MOVOU X4, -64(DI)(BX*1)
+ MOVOU X5, -48(DI)(BX*1)
+ MOVOU X6, -32(DI)(BX*1)
+ MOVOU X7, -16(DI)(BX*1)
+ RET