encoding/binary: PutUint* in benchmark optimized out

[shawndx]

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

$ go version
go version devel +a15b5d3092 Wed Dec 11 22:01:13 2019 +0000 linux/amd64

Does this issue reproduce with the latest release?

Yes.

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

go env Output

$ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/xiaji01/.cache/go-build"
GOENV="/home/xiaji01/.config/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/xiaji01/.go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/home/xiaji01/src/bench/go.x86"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/home/xiaji01/src/bench/go.x86/pkg/tool/linux_amd64"
GCCGO="gccgo"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/home/xiaji01/src/bench/go.x86/src/go.mod"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build896412687=/tmp/go-build -gno-record-gcc-switches"

What did you do?

go test -run=none -bench=PutUint encoding/binary
goos: linux
goarch: amd64
pkg: encoding/binary
BenchmarkPutUint16-40 1000000000 0.558 ns/op 3585.32 MB/s
BenchmarkPutUint32-40 1000000000 0.727 ns/op 5503.20 MB/s
BenchmarkPutUint64-40 1000000000 0.865 ns/op 9251.43 MB/s
BenchmarkLittleEndianPutUint16-40 1000000000 0.580 ns/op 3446.18 MB/s
BenchmarkLittleEndianPutUint32-40 1000000000 0.612 ns/op 6537.16 MB/s
BenchmarkLittleEndianPutUint64-40 1000000000 0.611 ns/op 13090.27 MB/s
PASS
ok encoding/binary 4.468s

What did you expect to see?

encoding/binary.bigEndian.PutUint[16,32,64] and encoding/binary.littleEndian.PutUint[16,32,64] get executed and profiled.

What did you see instead?

They are optimized out by compile optimization.

[randall77]

There isn't anything getting optimized out. That's the set of benchmarks that have been implemented.
The benchmarks are not generated automatically. Look in encoding/binary/binary_test.go.
Feel free to mail a CL that adds big endian versions.

[randall77]

Never mind, those benchmarks are there. They are the ones without LittleEndian in the names.
What did you want to see exactly, again?

[shawndx]

Thanks @randall77, my bad, double checked SSA output and the code is not optimized out.