Low-level SIMD abstraction layer for DiskANN. Provides portable vector operations across multiple ISA backends:

The default cargo test runs tests for the host machine's native ISA. To validate AArch64 on x86, test AVX-512 on a non-AVX-512 machine, or ensure that baseline x86-64 code does not execute invalid instructions, an emulator is needed.

Intel SDE emulates x86 with high fidelity. We use it to run AVX-512 code paths on AVX2-only machines and to emulate older CPUs to ensure binaries compiled for the x86-64 baseline behave correctly.

The steps below assume a Linux environment with SDE installed. On Windows, use CARGO_TARGET_X86_64_PC_WINDOWS_MSVC_RUNNER instead to point at the SDE binary.

WIDE_TEST_MIN_ARCH=x86-64-v4 \
CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_RUNNER="${PATH_TO_SDE} -spr --" \
  cargo test --profile ci --package diskann-wide

• CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_RUNNER tells Cargo to run every test binary through SDE automatically.
• WIDE_TEST_MIN_ARCH=x86-64-v4 tells diskann-wide tests to require V4, so tests that would otherwise be skipped at runtime are executed.
• -spr selects Sapphire Rapids, which supports all V4 target features. Any CPU model from Ice Lake onward is supported.

To verify that code compiled for the x86-64 baseline doesn't accidentally hit unsupported instructions, run under a Nehalem model:

RUSTFLAGS="-Ctarget-cpu=x86-64" \
CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_RUNNER="${PATH_TO_SDE} -nhm --" \
  cargo test --profile ci --package diskann-wide

SDE will abort if any AVX instruction is executed, catching accidental use of SIMD in baseline-compiled code.

QEMU user-mode emulation runs AArch64 binaries on x86 Linux hosts. This flow is unavailable on Windows and macOS.

First, install the cross-compiler and QEMU:

sudo apt install -y gcc-aarch64-linux-gnu qemu-user
rustup target add aarch64-unknown-linux-gnu

Then run tests:

WIDE_TEST_MIN_ARCH=neon \
CARGO_TARGET_AARCH64_UNKNOWN_LINUX_GNU_LINKER=aarch64-linux-gnu-gcc \
CARGO_TARGET_AARCH64_UNKNOWN_LINUX_GNU_RUNNER="qemu-aarch64 -L /usr/aarch64-linux-gnu" \
  cargo test --profile ci --package diskann-wide --target aarch64-unknown-linux-gnu

• -L /usr/aarch64-linux-gnu sets the sysroot so QEMU can find the AArch64 dynamic linker and libc.
• .cargo/config.toml already sets -Ctarget-feature=+neon,+dotprod, but WIDE_TEST_MIN_ARCH=neon double-checks that these features are applied.