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runtime: invalid instruction: XCHGQ with SP-relative address #19184

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davidlazar opened this issue Feb 19, 2017 · 2 comments

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commented Feb 19, 2017

$ go version
go version devel +1e69aefb7e Sat Feb 18 19:01:08 2017 +0000 linux/amd64

In the runtime directory:

$ go test -a -short -gcflags '-l=4'
# runtime                                   
./proc_runtime_test.go:34: invalid instruction: 00333 (/home/david/go/src/runtime/netpoll.go:247)	XCHGQ	AX, "".wg+24(SP)
./proc_runtime_test.go:34: invalid instruction: 00120 (/home/david/go/src/runtime/netpoll.go:272)	XCHGQ	AX, "".rg+24(SP)
# runtime
./write_err.go:14: invalid instruction: 00333 (/home/david/go/src/runtime/netpoll.go:247)	XCHGQ	AX, "".wg+24(SP)
./write_err.go:14: invalid instruction: 00120 (/home/david/go/src/runtime/netpoll.go:272)	XCHGQ	AX, "".rg+24(SP)
FAIL	runtime [build failed]

This is a result of inlining the atomicstorep function. Git bisect says that 1f77db9 is the first commit to exhibit this behavior. Prior to this commit, atomicstorep was mutually recursive,

atomicstorep -> writebarrierptr_prewrite -> writebarrierptr_prewrite1 -> writebarrierptr_prewrite1.func1 -> gcmarkwb_m -> shade -> greyobject -> (*gcWork).put -> (*gcControllerState).enlistWorker -> wakep -> startm -> newm -> allocm -> acquirep -> traceProcStart -> traceEvent -> traceStackID -> (*traceStackTable).put -> atomicstorep

which made it uninlineable. 1f77db9 broke the mutual recursion, allowing atomicstorep to get inlined.

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commented Feb 19, 2017

CL https://golang.org/cl/37253 mentions this issue.

@gopherbot gopherbot closed this in cfb0d34 Feb 19, 2017

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commented Feb 19, 2017

CL https://golang.org/cl/37255 mentions this issue.

gopherbot pushed a commit that referenced this issue Mar 1, 2017

cmd/compile: fix disassembly of invalid instructions
Make sure that if we encode an explicit base register, we print it.
That will ensure that if we make an Addr with an auto variable but
a base that isn't SP, then it will be obvious from the disassembly.

Update #19184

Change-Id: If5556a5183f344d719ec7197aa935a0166061e6f
Reviewed-on: https://go-review.googlesource.com/37255
Reviewed-by: Cherry Zhang <cherryyz@google.com>

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