testing: B.Loop fails to terminate early when it hits the 1 Billion iteration cap #75210
Description
Go version
go version go1.26-devel_8bcda6c79d Fri Aug 29 23:57:12 2025 -0700 linux/amd64
Output of go env in your module/workspace:
AR='ar'
CC='gcc'
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_ENABLED='1'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
CXX='g++'
GCCGO='/usr/bin/gccgo'
GO111MODULE=''
GOAMD64='v3'
GOARCH='amd64'
GOAUTH='netrc'
GOBIN=''
GOCACHE='/home/david/.cache/go-build'
GOCACHEPROG=''
GODEBUG=''
GOENV='/home/david/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFIPS140='off'
GOFLAGS=''
GOGCCFLAGS='-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build1806117217=/tmp/go-build -gno-record-gcc-switches'
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMOD='/home/david/src/go/src/golang.spin-2.net/gf2npoly/go.mod'
GOMODCACHE='/home/david/src/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/home/david/src/go:'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/home/david/sdk/gotip'
GOSUMDB='sum.golang.org'
GOTELEMETRY='local'
GOTELEMETRYDIR='/home/david/.config/go/telemetry'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/home/david/sdk/gotip/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.26-devel_8bcda6c79d Fri Aug 29 23:57:12 2025 -0700'
GOWORK=''
PKG_CONFIG='pkg-config'What did you do?
I converted the benchmarks in golang.spin-2.net/gf2npoly to use for B.Loop() instead of for range B.N
Running go test -bench Bench/public -count 3 -benchtime 5s .
What did you see happen?
% gotip test -bench Bench/public -count 3 -benchtime 5s . pts/1471701
goos: linux
goarch: amd64
pkg: golang.spin-2.net/gf2npoly
cpu: AMD Ryzen 9 5900X 12-Core Processor
BenchmarkGF2Mul64/public-24 1000000000 5.000 ns/op
BenchmarkGF2Mul64/public-24 1000000000 5.000 ns/op
BenchmarkGF2Mul64/public-24 1000000000 5.000 ns/op
BenchmarkGF2Mul64All1s/public-24 1000000000 5.000 ns/op
BenchmarkGF2Mul64All1s/public-24 1000000000 5.000 ns/op
BenchmarkGF2Mul64All1s/public-24 1000000000 5.000 ns/op
PASS
ok golang.spin-2.net/gf2npoly 30.009s
What did you expect to see?
% ~/src/build/compilers/go/bin/go test -bench Bench/public -count 3 -benchtime 2s . pts/1471707
goos: linux
goarch: amd64
pkg: golang.spin-2.net/gf2npoly
cpu: AMD Ryzen 9 5900X 12-Core Processor
BenchmarkGF2Mul64/public-24 747061556 3.199 ns/op
BenchmarkGF2Mul64/public-24 747226730 3.190 ns/op
BenchmarkGF2Mul64/public-24 746786904 3.189 ns/op
BenchmarkGF2Mul64All1s/public-24 698037858 3.396 ns/op
BenchmarkGF2Mul64All1s/public-24 706759926 3.406 ns/op
BenchmarkGF2Mul64All1s/public-24 708699562 3.404 ns/op
PASS
ok golang.spin-2.net/gf2npoly 14.354s