refactor(bazel): patch the kernel defines with a stock Bazel action

[Alexandr-Solovev]

Fourth PR of the dev/bazel simplification series. Stacked on #3830 — review that one first; the diff below is the last commit only.

What this removes

cpp/daal/include/services/internal/daal_kernel_defines.h enables every CPU dispatch variant oneDAL can build, and the ISAs that --cpu leaves out have to be stripped from it before it is compiled or released. That one regex substitution was implemented as a custom Bazel toolchain:

file	what it was for
toolchains/extra_toolchain.bzl	a provider + a toolchain rule
toolchains/extra_toolchain_lnx.bzl, _win.bzl	two repository rules
toolchains/extra_toolchain_extension.bzl	a module extension to instantiate them
toolchains/extra_toolchain_{lnx,win}.tpl.BUILD	two generated BUILD templates
toolchains/tools/patch_daal_kernel_defines.{sh,cmd,ps1}	three copies of the patcher
toolchain_type(name = "extra"), 3 lines in MODULE.bazel	the registration

Ten files, a custom toolchain type and a module extension, so that one action could run one sed.

ctx.actions.expand_template is the stock Bazel action for exactly this: it performs literal substitutions on a file at execution time, so nothing has to read the header during analysis and no helper tool is needed on either platform. The whole mechanism collapses to:

ctx.actions.expand_template(
    template = ctx.file.src,
    output = kernel_defines,
    substitutions = {
        "#define DAAL_KERNEL_{}".format(cpu.upper()): "\r" if is_windows else ""
        for cpu in disabled_cpus
    },
)

The Makefile's Windows behaviour — sed.eol is empty on Linux and a lone CR on Windows, so a disabled define leaves an empty line with the platform's own line ending — is expressed as the replacement string rather than as a separate script.

net -304 / +33 lines, and the dev/bazel/toolchains directory loses its second toolchain type.

Hermeticity fix

The old rule received the patcher through ExtraToolchainInfo as an attr.string absolute path and passed it to ctx.actions.run(executable = ...) without ever declaring it as an input. Editing patch_daal_kernel_defines.sh therefore did not invalidate the cached output. The new implementation has no tool at all, so the only inputs are the header and the --cpu setting, both of which Bazel already tracks.

Validation

• The generated header is byte-identical to the previous implementation's output for --cpu=all, --cpu=avx512, --cpu=avx2 and --cpu=sse2 (captured before the change, compared after).
• bazel build //cpp/daal:core_static //cpp/oneapi/dal/algo:kmeans_dpc is a full action-cache hit against the pre-change cache — no command line changed.
• bazel build --nobuild //:release //:release_all //examples/oneapi/cpp:all analyses clean.
• Repo-wide grep confirms no remaining reference to extra_toolchain, ExtraToolchainInfo, patch_daal_kernel_defines or //dev/bazel/toolchains:extra.

The Windows path has no CI coverage here; it is unchanged in intent and the replacement string reproduces what patch_daal_kernel_defines.ps1 wrote.

[Copilot]

Copilot review overview

🔵 Needs a closer look

The stacked cross-platform toolchain refactor includes Windows-specific behavior without CI coverage and warrants final human validation.

Review effort: Balanced
Findings: None

What changed in this PR

Replaces the custom kernel-definition patching toolchain with Bazel’s hermetic expand_template action, while incorporating the stacked shared toolchain configuration refactor.

Changes:

• Patches disabled ISA defines directly with a tracked Bazel action.
• Removes the extra toolchain, platform wrappers, templates, and scripts.
• Consolidates shared Linux/Windows C++ toolchain configuration.

File	Description
.bazelrc	Removes empty configuration and trailing whitespace.
MODULE.bazel	Removes extra toolchain registration.
dev/​bazel/​cc.bzl	Restricts release-copy helper to Windows.
dev/​bazel/​cc/​common.bzl	Removes an unused utility import.
dev/​bazel/​cc/​link.bzl	Removes an unused utility import.
dev/​bazel/​daal.bzl	Uses expand_template to patch ISA defines.
dev/​bazel/​release.bzl	Removes the unused extra toolchain dependency.
dev/​bazel/​toolchains/​BUILD	Removes the obsolete toolchain type.
dev/​bazel/​toolchains/​cc_toolchain_config_common.bzl	Adds shared toolchain features and attributes.
dev/​bazel/​toolchains/​cc_toolchain_config_lnx.bzl	Uses the shared Linux/Windows configuration.
dev/​bazel/​toolchains/​cc_toolchain_config_win.bzl	Uses the shared Linux/Windows configuration.
dev/​bazel/​toolchains/​extra_toolchian_lnx.tpl.BUILD	Deletes the Linux extra-toolchain template.
dev/​bazel/​toolchains/​extra_toolchain.bzl	Deletes the custom toolchain implementation.
dev/​bazel/​toolchains/​extra_toolchain_extension.bzl	Deletes the module extension.
dev/​bazel/​toolchains/​extra_toolchain_lnx.bzl	Deletes Linux repository setup.
dev/​bazel/​toolchains/​extra_toolchain_win.bzl	Deletes Windows repository setup.
dev/​bazel/​toolchains/​extra_toolchain_win.tpl.BUILD	Deletes the Windows extra-toolchain template.
dev/​bazel/​toolchains/​tools/​patch_daal_kernel_defines.cmd	Deletes the Windows launcher.
dev/​bazel/​toolchains/​tools/​patch_daal_kernel_defines.ps1	Deletes the Windows patcher.
dev/​bazel/​toolchains/​tools/​patch_daal_kernel_defines.sh	Deletes the Linux patcher.

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[napetrov]

Measured locally: Linux x86, Bazel 9.2.0, gcc 13.3, icpx 2025.2; clean env (env -i, no MKLROOT/TBBROOT); one worktree + output base per head, base = merge-base 3120d0ab.

• Patched daal_kernel_defines.h is byte-identical to base for --cpu = all, avx512, avx2, sse2, "avx2 avx512", auto. Walking #3830 -> this head in one output base re-runs only 2 internal actions; the other 3225 are cache hits.
• The LinuxBazelGNU_OpenBLAS_rv64 failure (Azure build 63735, install bazel step) is :error: Failed to fetch Bazelisk release information from GitHub API. - a rate limit, unrelated to this diff. #3835 hit the same thing.
• Nit: the description says Windows has no CI coverage, but WindowsBazel ran on this head and was green, so the \r path is exercised.

[napetrov]

This is a literal, unanchored replace, so it also hits longer macro names and any other mention of the macro. Demonstrated by adding two lines to the header and building with --cpu=sse2:

#define DAAL_KERNEL_AVX2_VNNI                 ->  _VNNI
/* mirrors #define DAAL_KERNEL_AVX512 */      ->  /* mirrors  */

Make's sed 's/^#define DAAL_KERNEL_X\b//' leaves both lines alone. The docstring's "mentions those macros nowhere else" holds today but nothing enforces it; it breaks silently the day someone adds an AVX2_VNNI / AVX512_* style variant.

Anchoring on the whole line keeps it equivalent, e.g. key "\n#define DAAL_KERNEL_{}\n".format(cpu.upper()) -> "\n\r\n" if is_windows else "\n\n" (the header is eol=lf per .gitattributes, and no define sits on line 1).

[Alexandr-Solovev]

Agreed, fixed in ab76a83: the key is now "\n#define DAAL_KERNEL_<ISA>\n" -> "\n\n" ("\n\r\n" on Windows), and the docstring is updated. I checked it with your two lines added and --cpu=sse2: AVX2 and AVX512 are blanked (adjacent defines still match one after another, since each replacement keeps its trailing newline), and #define DAAL_KERNEL_AVX2_VNNI and the /* mirrors ... */ comment pass through unchanged.

[Alexandr-Solovev]

Superseded by #3833, which now carries this PR's commits unchanged (plus the review fixes made here), rebased on current main, together with the rest of the dev/bazel series. Closing to avoid reviewing and merging the same changes twice.