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| author | Austin Clements <austin@google.com> | 2017-11-15 14:54:24 -0800 |
|---|---|---|
| committer | Austin Clements <austin@google.com> | 2018-02-13 16:34:17 +0000 |
| commit | 1de1f316df84569c449d6d709b0d711921ea6116 (patch) | |
| tree | 8ac47388708fe13a4f86bc27e780185be5b9a7a3 /src/runtime/asm_arm.s | |
| parent | 24dd83d7eb0f08ea5cf541ead3f2b36448468bfa (diff) | |
| download | go-1de1f316df84569c449d6d709b0d711921ea6116.tar.gz go-1de1f316df84569c449d6d709b0d711921ea6116.zip | |
runtime: buffered write barrier for arm
Updates #22460.
Change-Id: I5581df7ad553237db7df3701b117ad99e0593b78
Reviewed-on: https://go-review.googlesource.com/92698
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Diffstat (limited to 'src/runtime/asm_arm.s')
| -rw-r--r-- | src/runtime/asm_arm.s | 58 |
1 files changed, 58 insertions, 0 deletions
diff --git a/src/runtime/asm_arm.s b/src/runtime/asm_arm.s index d10c370a7d..0b429705e8 100644 --- a/src/runtime/asm_arm.s +++ b/src/runtime/asm_arm.s @@ -1054,3 +1054,61 @@ TEXT ·checkASM(SB),NOSPLIT,$0-1 MOVW $1, R3 MOVB R3, ret+0(FP) RET + +// gcWriteBarrier performs a heap pointer write and informs the GC. +// +// gcWriteBarrier does NOT follow the Go ABI. It takes two arguments: +// - R2 is the destination of the write +// - R3 is the value being written at R2 +// It clobbers condition codes. +// It does not clobber any other general-purpose registers, +// but may clobber others (e.g., floating point registers). +// The act of CALLing gcWriteBarrier will clobber R14 (LR). +TEXT runtime·gcWriteBarrier(SB),NOSPLIT|NOFRAME,$0 + // Save the registers clobbered by the fast path. + MOVM.DB.W [R0,R1], (R13) + MOVW g_m(g), R0 + MOVW m_p(R0), R0 + MOVW (p_wbBuf+wbBuf_next)(R0), R1 + // Increment wbBuf.next position. + ADD $8, R1 + MOVW R1, (p_wbBuf+wbBuf_next)(R0) + MOVW (p_wbBuf+wbBuf_end)(R0), R0 + CMP R1, R0 + // Record the write. + MOVW R3, -8(R1) // Record value + MOVW (R2), R0 // TODO: This turns bad writes into bad reads. + MOVW R0, -4(R1) // Record *slot + // Is the buffer full? (flags set in CMP above) + B.EQ flush +ret: + MOVM.IA.W (R13), [R0,R1] + // Do the write. + MOVW R3, (R2) + // Normally RET on nacl clobbers R12, but because this + // function has no frame it doesn't have to usual epilogue. + RET + +flush: + // Save all general purpose registers since these could be + // clobbered by wbBufFlush and were not saved by the caller. + // + // R0 and R1 were saved at entry. + // R10 is g, so preserved. + // R11 is linker temp, so no need to save. + // R13 is stack pointer. + // R15 is PC. + // + // This also sets up R2 and R3 as the arguments to wbBufFlush. + MOVM.DB.W [R2-R9,R12], (R13) + // Save R14 (LR) because the fast path above doesn't save it, + // but needs it to RET. This is after the MOVM so it appears below + // the arguments in the stack frame. + MOVM.DB.W [R14], (R13) + + // This takes arguments R2 and R3. + CALL runtime·wbBufFlush(SB) + + MOVM.IA.W (R13), [R14] + MOVM.IA.W (R13), [R2-R9,R12] + JMP ret |