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cmd/compile: link fails when function containing linknamed symbol is inlined (-l=4) #18167

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davidlazar opened this issue Dec 2, 2016 · 2 comments
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cmd/compile: link fails when function containing linknamed symbol is inlined (-l=4) #18167

davidlazar opened this issue Dec 2, 2016 · 2 comments
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FrozenDueToAge NeedsFix The path to resolution is known, but the work has not been done.
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Go1.9

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@davidlazar
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The net/http tests fail with -l=4:

$ go version
go version devel +5c9035a Fri Dec 2 19:19:03 2016 +0000 linux/amd64

$ cd $GOROOT/src/net/http
$ go test -a -gcflags '-l=4' -v .                         
# testmain
net/http.(*http2Transport).RoundTripOpt: relocation target net.byteIndex not defined
net/http.(*http2Transport).RoundTripOpt: relocation target net.byteIndex not defined
net/http.(*http2ClientConn).encodeHeaders: relocation target net.byteIndex not defined
net/http.(*http2ClientConn).encodeHeaders: relocation target net.byteIndex not defined
net/http.cleanHost: relocation target net.byteIndex not defined
net/http.cleanHost: relocation target net.byteIndex not defined
...
net/http.cleanHost: undefined: "net.byteIndex"
/home/david/go/pkg/tool/linux_amd64/link: too many errors
FAIL	net/http [build failed]

Let's look at the cleanHost function in net/http/request.go to understand what's happening. The cleanHost function calls net.JoinHostPort, which is inlined by the compiler. The body of net.JoinHostPort has a call to net.byteIndex which is linknamed in net/parse.go:

//go:linkname byteIndex strings.IndexByte
func byteIndex(s string, c byte) int

The export data used to inline net.JoinHostPort does not include linknames, so the compiler can't find net.byteIndex when it appears in the body of cleanHost after inlining.

One solution is to include linknames in export data.
@davidlazar davidlazar self-assigned this Dec 2, 2016
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CL https://golang.org/cl/33911 mentions this issue.

@quentinmit quentinmit added the NeedsFix The path to resolution is known, but the work has not been done. label Dec 6, 2016
@quentinmit quentinmit added this to the Go1.9 milestone Dec 6, 2016
@quentinmit
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This is too late for Go 1.8.

@golang golang locked and limited conversation to collaborators Feb 8, 2018
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FrozenDueToAge NeedsFix The path to resolution is known, but the work has not been done.
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