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Run the 386 lane without an emulator, because qemu-i386 loses float state #26

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Merged
tannevaled merged 1 commit into from
Sep 26, 2026
Merged

Run the 386 lane without an emulator, because qemu-i386 loses float state #26

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29 changes: 22 additions & 7 deletions .github/workflows/ci.yml
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Original file line number Diff line number Diff line change
Expand Up @@ -69,17 +69,32 @@ jobs:
fail-fast: false
matrix:
include:
- { goarch: riscv64, qemu: qemu-riscv64-static }
- { goarch: loong64, qemu: qemu-loongarch64-static }
- { goarch: ppc64le, qemu: qemu-ppc64le-static }
- { goarch: s390x, qemu: qemu-s390x-static }
- { goarch: "386", qemu: qemu-i386-static }
- { goarch: arm, qemu: qemu-arm-static }
- { goarch: riscv64, exec: "-exec=qemu-riscv64-static" }
- { goarch: loong64, exec: "-exec=qemu-loongarch64-static" }
- { goarch: ppc64le, exec: "-exec=qemu-ppc64le-static" }
- { goarch: s390x, exec: "-exec=qemu-s390x-static" }
# 386 runs with NO emulator: a 386 ELF executes directly on the
# x86-64 runner. That is not a convenience, it is a correctness
# requirement. Measured on one commit of go-gfx/gfx, eight identical
# lanes each:
#
# under qemu-i386 5 failures out of 8
# under qemu-i386, asyncpreemptoff=1 0 out of 8
# native on the same runner 0 out of 8
# under qemu-arm 0 out of 8
#
# Each failure landed on a DIFFERENT input although the seed is
# fixed, and the wrong value was a sign flip rather than a rounding
# difference. qemu-i386 loses the guest's floating-point state across
# the signal Go delivers for asynchronous preemption. Emulating 386
# here would buy nothing and cost a lane that goes red at random.
- { goarch: "386", exec: "" }
- { goarch: arm, exec: "-exec=qemu-arm-static" }
steps:
- uses: actions/checkout@v7
- uses: actions/setup-go@v7
with:
go-version: "1.27.1"
- run: sudo apt-get update && sudo apt-get install -y qemu-user-static
- name: Test under qemu (${{ matrix.goarch }})
run: GOARCH=${{ matrix.goarch }} go test -exec=${{ matrix.qemu }} ./...
run: GOARCH=${{ matrix.goarch }} go test ${{ matrix.exec }} ./...
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