1. What version of Go are you using (go version)?

go version go1.6 linux/amd64

1. What operating system and processor architecture are you using (go env)?

GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/go"
GORACE=""
GOROOT="/usr/local/go"
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GO15VENDOREXPERIMENT="1"
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0"
CXX="g++"
CGO_ENABLED="1"

1. What did you do?

Given this example:
https://play.golang.org/p/LqaVgTCP57

Compiling it with default optimization options correctly inlines the call to the empty function f() but its argument, even if not "consumed" by anything in the inlined call to f() is still computed. I was expecting a deeper optimization level correctly seeing that these rvalues are not used at all when f() is empty.

Here are the output of gc using the -S flag with and without inlining to highlight the fact that the computation of the arguments are still here whether the inlining results in a noop or not.

$ go build -gcflags='-S' example.go
...
        0x0000 00000 (/home/julio/farjump/lab/example.go:11)    MOVQ    $42, AX
        0x0007 00007 (/home/julio/farjump/lab/example.go:12)    CMPQ    AX, $42
        0x000b 00011 (/home/julio/farjump/lab/example.go:12)    SETEQ   AL
...

$ go build -gcflags='-l -S' example.go
...
        0x0018 00024 (/home/julio/farjump/lab/example.go:11)    MOVQ    (SP), BX
        0x001c 00028 (/home/julio/farjump/lab/example.go:12)    CMPQ    BX, $42
        0x0020 00032 (/home/julio/farjump/lab/example.go:12)    SETEQ   (SP)
        0x0024 00036 (/home/julio/farjump/lab/example.go:12)    PCDATA  $0, $0
        0x0024 00036 (/home/julio/farjump/lab/example.go:12)    CALL    "".f(SB)
...

1. What did you expect to see?

The data-flow analyser should be able to delete useless arguments (and associated computations).

1. What did you see instead?

Useless instructions.