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87e48c5afd
Since barrier-less memclr is only safe in very narrow circumstances, this commit renames memclr to avoid accidentally calling memclr on typed memory. This can cause subtle, non-deterministic bugs, so it's worth some effort to prevent. In the near term, this will also prevent bugs creeping in from any concurrent CLs that add calls to memclr; if this happens, whichever patch hits master second will fail to compile. This also adds the other new memclr variants to the compiler's builtin.go to minimize the churn on that binary blob. We'll use these in future commits. Updates #17503. Change-Id: I00eead049f5bd35ca107ea525966831f3d1ed9ca Reviewed-on: https://go-review.googlesource.com/31369 Reviewed-by: Keith Randall <khr@golang.org> Reviewed-by: Rick Hudson <rlh@golang.org>
63 lines
1.6 KiB
ArmAsm
63 lines
1.6 KiB
ArmAsm
// Copyright 2014 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build ppc64 ppc64le
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#include "textflag.h"
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// void runtime·memclrNoHeapPointers(void*, uintptr)
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TEXT runtime·memclrNoHeapPointers(SB), NOSPLIT|NOFRAME, $0-16
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MOVD ptr+0(FP), R3
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MOVD n+8(FP), R4
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// Determine if there are doublewords to clear
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check:
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ANDCC $7, R4, R5 // R5: leftover bytes to clear
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SRAD $3, R4, R6 // R6: double words to clear
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CMP R6, $0, CR1 // CR1[EQ] set if no double words
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BC 12, 6, nozerolarge // only single bytes
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MOVD R6, CTR // R6 = number of double words
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SRADCC $2, R6, R7 // 32 byte chunks?
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BNE zero32setup
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// Clear double words
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zero8:
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MOVD R0, 0(R3) // double word
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ADD $8, R3
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BC 16, 0, zero8 // dec ctr, br zero8 if ctr not 0
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BR nozerolarge // handle remainder
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// Prepare to clear 32 bytes at a time.
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zero32setup:
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DCBTST (R3) // prepare data cache
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MOVD R7, CTR // number of 32 byte chunks
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zero32:
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MOVD R0, 0(R3) // clear 4 double words
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MOVD R0, 8(R3)
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MOVD R0, 16(R3)
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MOVD R0, 24(R3)
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ADD $32, R3
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BC 16, 0, zero32 // dec ctr, br zero32 if ctr not 0
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RLDCLCC $61, R4, $3, R6 // remaining doublewords
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BEQ nozerolarge
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MOVD R6, CTR // set up the CTR for doublewords
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BR zero8
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nozerolarge:
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CMP R5, $0 // any remaining bytes
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BC 4, 1, LR // ble lr
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zerotail:
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MOVD R5, CTR // set up to clear tail bytes
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zerotailloop:
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MOVB R0, 0(R3) // clear single bytes
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ADD $1, R3
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BC 16, 0, zerotailloop // dec ctr, br zerotailloop if ctr not 0
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RET
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