Hi Keith, thank you for your response. Sorry I didn't say that I saw this
issue on linux/arm64. For your example above, the result on linux/arm64 is
like this:
go tool compile -S tmp.go
0x001c 00028 (spill.go:4) MOVD "".p(FP), R0
0x0020 00032 (spill.go:4) MOVH (R0), R1
0x0024 00036 (spill.go:4) MOVH R1, "".x-8(SP)
0x0028 00040 (spill.go:5) MOVD "".q+8(FP), R2
0x002c 00044 (spill.go:5) MOVH (R2), R3
0x0030 00048 (spill.go:5) MOVH R3, "".y-16(SP)
0x0034 00052 (spill.go:6) PCDATA $1, ZR
0x0034 00052 (spill.go:6) CALL "".g(SB)
0x0038 00056 (spill.go:7) MOVH "".y-16(SP), R0
0x003c 00060 (spill.go:7) MOVD "".p(FP), R1
0x0040 00064 (spill.go:7) MOVH R0, (R1)
0x0044 00068 (spill.go:8) MOVH "".x-8(SP), R0
0x0048 00072 (spill.go:8) MOVD "".q+8(FP), R1
0x004c 00076 (spill.go:8) MOVH R0, (R1)
Obviously it is 8 bytes.
在2020年11月4日星期三 UTC+8 上午6:39:30<Keith Randall> 写道：
> It don't think it does. For instance, an int16 will be spilled to a 2-byte
> slot in the stack frame.
> Can you show us what you are seeing? This is what I tried:
>
> package main
>
> func f(p, q *int16) {
> x := *p
> y := *q
> g()
> *p = y
> *q = x
> }
> func g()
>
> go tool compile -S tmp.go
>
> 0x001d 00029 (tmp1.go:4) MOVQ "".p+24(SP), AX
> 0x0022 00034 (tmp1.go:4) MOVWLZX (AX), CX
> 0x0025 00037 (tmp1.go:4) MOVW CX, "".x+6(SP)
> 0x002a 00042 (tmp1.go:5) MOVQ "".q+32(SP), DX
> 0x002f 00047 (tmp1.go:5) MOVWLZX (DX), BX
> 0x0032 00050 (tmp1.go:5) MOVW BX, "".y+4(SP)
> 0x0037 00055 (tmp1.go:6) CALL "".g(SB)
> 0x003c 00060 (tmp1.go:7) MOVWLZX "".y+4(SP), AX
> 0x0041 00065 (tmp1.go:7) MOVQ "".p+24(SP), CX
> 0x0046 00070 (tmp1.go:7) MOVW AX, (CX)
> 0x0049 00073 (tmp1.go:8) MOVWLZX "".x+6(SP), AX
> 0x004e 00078 (tmp1.go:8) MOVQ "".q+32(SP), CX
> 0x0053 00083 (tmp1.go:8) MOVW AX, (CX)
>
>
> On Monday, November 2, 2020 at 3:29:49 AM UTC-8 [email protected] wrote:
>
>> Hi,
>>
>> Can someone tell me why does OpStoreReg of type int16, int32, etc. occupy
>> 8 bytes on the stack? And where is this handled ? Thanks.
>>
>
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