[bazel] Improve building on/for Windows#171761
Open
+130 −74
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters. Learn more about bidirectional Unicode characters
dzbarsky requested review from aaronmondal, keith and rupprecht as code owners
llvmbot added llvm:support bazel 
Member
llvmbot commented Dec 11, 2025
@llvm/pr-subscribers-llvm-support Author: David Zbarsky (dzbarsky) ChangesFew things going on here:
With this set of changes (as well as another one that rewrites Full diff: https://github.com/llvm/llvm-project/pull/171761.diff 7 Files Affected:
diff --git a/llvm/lib/Support/BLAKE3/blake3_avx2_x86-64_unix.S b/llvm/lib/Support/BLAKE3/blake3_avx2_x86-64_unix.S index e98893c7ef8b8..d6fa51638da39 100644 --- a/llvm/lib/Support/BLAKE3/blake3_avx2_x86-64_unix.S+++ b/llvm/lib/Support/BLAKE3/blake3_avx2_x86-64_unix.S@@ -16,15 +16,17 @@ #define _CET_ENDBR #endif -#ifdef __APPLE__-#define HIDDEN .private_extern+#if defined(__APPLE__)+#define HIDDEN(symbol) .private_extern symbol+#elif defined(__ELF__)+#define HIDDEN(symbol) .hidden symbol #else -#define HIDDEN .hidden+#define HIDDEN(symbol) #endif .intel_syntax noprefix -HIDDEN _blake3_hash_many_avx2-HIDDEN blake3_hash_many_avx2+HIDDEN(_blake3_hash_many_avx2)+HIDDEN(blake3_hash_many_avx2) .global _blake3_hash_many_avx2 .global blake3_hash_many_avx2 #ifdef __APPLE__ diff --git a/llvm/lib/Support/BLAKE3/blake3_avx512_x86-64_unix.S b/llvm/lib/Support/BLAKE3/blake3_avx512_x86-64_unix.S index b4b14946de10e..cf2c88329af5c 100644 --- a/llvm/lib/Support/BLAKE3/blake3_avx512_x86-64_unix.S+++ b/llvm/lib/Support/BLAKE3/blake3_avx512_x86-64_unix.S@@ -16,21 +16,23 @@ #define _CET_ENDBR #endif -#ifdef __APPLE__-#define HIDDEN .private_extern+#if defined(__APPLE__)+#define HIDDEN(symbol) .private_extern symbol+#elif defined(__ELF__)+#define HIDDEN(symbol) .hidden symbol #else -#define HIDDEN .hidden+#define HIDDEN(symbol) #endif .intel_syntax noprefix -HIDDEN _blake3_hash_many_avx512-HIDDEN blake3_hash_many_avx512-HIDDEN blake3_compress_in_place_avx512-HIDDEN _blake3_compress_in_place_avx512-HIDDEN blake3_compress_xof_avx512-HIDDEN _blake3_compress_xof_avx512-HIDDEN blake3_xof_many_avx512-HIDDEN _blake3_xof_many_avx512+HIDDEN(_blake3_hash_many_avx512)+HIDDEN(blake3_hash_many_avx512)+HIDDEN(blake3_compress_in_place_avx512)+HIDDEN(_blake3_compress_in_place_avx512)+HIDDEN(blake3_compress_xof_avx512)+HIDDEN(_blake3_compress_xof_avx512)+HIDDEN(blake3_xof_many_avx512)+HIDDEN(_blake3_xof_many_avx512) .global _blake3_hash_many_avx512 .global blake3_hash_many_avx512 .global blake3_compress_in_place_avx512 diff --git a/llvm/lib/Support/BLAKE3/blake3_sse2_x86-64_unix.S b/llvm/lib/Support/BLAKE3/blake3_sse2_x86-64_unix.S index d69a1706fefe7..5563fc3b5ba09 100644 --- a/llvm/lib/Support/BLAKE3/blake3_sse2_x86-64_unix.S+++ b/llvm/lib/Support/BLAKE3/blake3_sse2_x86-64_unix.S@@ -16,19 +16,21 @@ #define _CET_ENDBR #endif -#ifdef __APPLE__-#define HIDDEN .private_extern+#if defined(__APPLE__)+#define HIDDEN(symbol) .private_extern symbol+#elif defined(__ELF__)+#define HIDDEN(symbol) .hidden symbol #else -#define HIDDEN .hidden+#define HIDDEN(symbol) #endif .intel_syntax noprefix -HIDDEN blake3_hash_many_sse2-HIDDEN _blake3_hash_many_sse2-HIDDEN blake3_compress_in_place_sse2-HIDDEN _blake3_compress_in_place_sse2-HIDDEN blake3_compress_xof_sse2-HIDDEN _blake3_compress_xof_sse2+HIDDEN(blake3_hash_many_sse2)+HIDDEN(_blake3_hash_many_sse2)+HIDDEN(blake3_compress_in_place_sse2)+HIDDEN(_blake3_compress_in_place_sse2)+HIDDEN(blake3_compress_xof_sse2)+HIDDEN(_blake3_compress_xof_sse2) .global blake3_hash_many_sse2 .global _blake3_hash_many_sse2 .global blake3_compress_in_place_sse2 diff --git a/llvm/lib/Support/BLAKE3/blake3_sse41_x86-64_unix.S b/llvm/lib/Support/BLAKE3/blake3_sse41_x86-64_unix.S index c5b103af61c4f..5866bfb7ae461 100644 --- a/llvm/lib/Support/BLAKE3/blake3_sse41_x86-64_unix.S+++ b/llvm/lib/Support/BLAKE3/blake3_sse41_x86-64_unix.S@@ -16,19 +16,21 @@ #define _CET_ENDBR #endif -#ifdef __APPLE__-#define HIDDEN .private_extern+#if defined(__APPLE__)+#define HIDDEN(symbol) .private_extern symbol+#elif defined(__ELF__)+#define HIDDEN(symbol) .hidden symbol #else -#define HIDDEN .hidden+#define HIDDEN(symbol) #endif .intel_syntax noprefix -HIDDEN blake3_hash_many_sse41-HIDDEN _blake3_hash_many_sse41-HIDDEN blake3_compress_in_place_sse41-HIDDEN _blake3_compress_in_place_sse41-HIDDEN blake3_compress_xof_sse41-HIDDEN _blake3_compress_xof_sse41+HIDDEN(blake3_hash_many_sse41)+HIDDEN(_blake3_hash_many_sse41)+HIDDEN(blake3_compress_in_place_sse41)+HIDDEN(_blake3_compress_in_place_sse41)+HIDDEN(blake3_compress_xof_sse41)+HIDDEN(_blake3_compress_xof_sse41) .global blake3_hash_many_sse41 .global _blake3_hash_many_sse41 .global blake3_compress_in_place_sse41 diff --git a/utils/bazel/llvm-project-overlay/clang/BUILD.bazel b/utils/bazel/llvm-project-overlay/clang/BUILD.bazel index d3bade579f003..0d1c4a800c9df 100644 --- a/utils/bazel/llvm-project-overlay/clang/BUILD.bazel+++ b/utils/bazel/llvm-project-overlay/clang/BUILD.bazel@@ -4,6 +4,8 @@ load("@rules_cc//cc:defs.bzl", "cc_binary", "cc_library") load("@rules_python//python:defs.bzl", "py_binary") +load("@bazel_lib//lib:run_binary.bzl", "run_binary")+load("@bazel_skylib//rules:write_file.bzl", "write_file") load( "//:vars.bzl", "LLVM_VERSION_MAJOR", @@ -577,23 +579,18 @@ exports_files( glob(["include/**/*.td"]), ) -genrule(+write_file( name = "basic_version_gen", - outs = ["include/clang/Basic/Version.inc"],- cmd = (- "echo '#define CLANG_VERSION{vers}' >> $@\n" +- "echo '#define CLANG_VERSION_MAJOR{major}' >> $@\n" +- "echo '#define CLANG_VERSION_MAJOR_STRING \"{major}\"' >> $@\n" +- "echo '#define CLANG_VERSION_MINOR{minor}' >> $@\n" +- "echo '#define CLANG_VERSION_PATCHLEVEL{patch}' >> $@\n" +- "echo '#define MAX_CLANG_ABI_COMPAT_VERSION{major}' >> $@\n" +- "echo '#define CLANG_VERSION_STRING \"{vers}\"' >> $@\n"- ).format(- major = LLVM_VERSION_MAJOR,- minor = LLVM_VERSION_MINOR,- patch = LLVM_VERSION_PATCH,- vers = PACKAGE_VERSION,- ),+ out = "include/clang/Basic/Version.inc",+ content = [+ "#define CLANG_VERSION{}".format(PACKAGE_VERSION),+ "#define CLANG_VERSION_MAJOR{}".format(LLVM_VERSION_MAJOR),+ "#define CLANG_VERSION_MAJOR_STRING \"{}\"".format(LLVM_VERSION_MAJOR),+ "#define CLANG_VERSION_MINOR{}".format(LLVM_VERSION_MINOR),+ "#define CLANG_VERSION_PATCHLEVEL{}".format(LLVM_VERSION_PATCH),+ "#define MAX_CLANG_ABI_COMPAT_VERSION{}".format(LLVM_VERSION_MAJOR),+ "#define CLANG_VERSION_STRING \"{}\"".format(PACKAGE_VERSION),+ ], ) cc_library( @@ -611,13 +608,15 @@ cc_library( # TODO: This should get replaced with something that actually generates the # correct version number. -genrule(+write_file( name = "vcs_version_gen", # This should be under lib/Basic, but because of how the include paths # are passed through bazel, it's easier to drop generated files next to # the other includes. - outs = ["include/VCSVersion.inc"],- cmd = "echo '#undef CLANG_REVISION' > $@",+ out = "include/VCSVersion.inc",+ content = [+ "#undef CLANG_REVISION",+ ], ) py_binary( @@ -979,16 +978,21 @@ cc_library( ], ) -genrule(+run_binary( name = "analysis_htmllogger_gen", + tool = ":bundle_resources", srcs = [ "lib/Analysis/FlowSensitive/HTMLLogger.html", "lib/Analysis/FlowSensitive/HTMLLogger.css", "lib/Analysis/FlowSensitive/HTMLLogger.js", ], outs = ["lib/Analysis/FlowSensitive/HTMLLogger.inc"], - cmd = "$(location :bundle_resources) $@ $(SRCS)",- tools = [":bundle_resources"],+ args = [+ "$@",+ "$(execpath lib/Analysis/FlowSensitive/HTMLLogger.html)",+ "$(execpath lib/Analysis/FlowSensitive/HTMLLogger.css)",+ "$(execpath lib/Analysis/FlowSensitive/HTMLLogger.js)",+ ], ) cc_library( @@ -1549,7 +1553,9 @@ cc_library( "lib/Driver", ], linkopts = select({- "@platforms//os:windows": ["version.lib"],+ "//llvm:is_windows_clang_mingw": ["-lversion"],+ "//llvm:is_windows_clang_cl": ["version.lib"],+ "//llvm:is_windows_msvc": ["version.lib"], "//conditions:default": [], }), textual_hdrs = glob([ diff --git a/utils/bazel/llvm-project-overlay/lld/BUILD.bazel b/utils/bazel/llvm-project-overlay/lld/BUILD.bazel index 1118f5e81f7ed..6f830ba72a0a2 100644 --- a/utils/bazel/llvm-project-overlay/lld/BUILD.bazel+++ b/utils/bazel/llvm-project-overlay/lld/BUILD.bazel@@ -10,6 +10,7 @@ load( load("//llvm:binary_alias.bzl", "binary_alias") load("//llvm:driver.bzl", "llvm_driver_cc_binary") load("//mlir:tblgen.bzl", "gentbl_cc_library") +load("@bazel_skylib//rules:write_file.bzl", "write_file") package( default_visibility = ["//visibility:public"], @@ -19,17 +20,21 @@ package( licenses(["notice"]) # TODO: Actually compute version info -genrule(+write_file( name = "config_version_gen", - outs = ["include/lld/Common/Version.inc"],- cmd = "echo '#define LLD_VERSION_STRING \"{}\"' > $@".format(LLVM_VERSION),+ out = "include/lld/Common/Version.inc",+ content = [+ "#define LLD_VERSION_STRING \"{}\"".format(LLVM_VERSION),+ ], ) -genrule(+write_file( name = "vcs_version_gen", - outs = ["Common/VCSVersion.inc"],- cmd = "echo '#undef LLD_REVISION' >> $@\n" +- "echo '#undef LLD_REPOSITORY' >> $@\n",+ out = "Common/VCSVersion.inc",+ content = [+ "#undef LLD_REVISION",+ "#undef LLD_REPOSITORY",+ ], ) # See https://github.com/bazelbuild/bazel/issues/13803 diff --git a/utils/bazel/llvm-project-overlay/llvm/BUILD.bazel b/utils/bazel/llvm-project-overlay/llvm/BUILD.bazel index 127bd7968ef0a..98d0cfe55f44e 100644 --- a/utils/bazel/llvm-project-overlay/llvm/BUILD.bazel+++ b/utils/bazel/llvm-project-overlay/llvm/BUILD.bazel@@ -4,6 +4,7 @@ load("@bazel_skylib//rules:common_settings.bzl", "string_flag") load("@bazel_skylib//rules:expand_template.bzl", "expand_template") +load("@bazel_skylib//rules:write_file.bzl", "write_file") load("@rules_cc//cc:defs.bzl", "cc_binary", "cc_library") load("@rules_python//python:defs.bzl", "py_binary") load("@rules_shell//shell:sh_binary.bzl", "sh_binary") @@ -208,18 +209,40 @@ cc_library( deps = [":config"], ) -genrule(+write_file( name = "generate_vcs_revision", - outs = ["include/llvm/Support/VCSRevision.h"],- cmd = "echo '#undef LLVM_REVISION' >> $@\n" +- "echo '#undef LLVM_REPOSITORY' >> $@\n",+ out = "include/llvm/Support/VCSRevision.h",+ content = [+ "#undef LLVM_REVISION",+ "#undef LLVM_REPOSITORY",+ ], ) -genrule(+write_file( name = "generate_static_extension_registry", - outs = ["include/llvm/Support/Extension.def"],- cmd = "echo -e '// extension handlers' >> $@\n" +- "echo -e '#undef HANDLE_EXTENSION' >> $@\n",+ out = "include/llvm/Support/Extension.def",+ content = [+ "// extension handlers",+ "#undef HANDLE_EXTENSION",+ ],+)++config_setting(+ name = "is_windows_clang_mingw",+ constraint_values = ["@platforms//os:windows"],+ flag_values ={"@rules_cc//cc/compiler:compiler": "clang"},+)++config_setting(+ name = "is_windows_clang_cl",+ constraint_values = ["@platforms//os:windows"],+ flag_values ={"@rules_cc//cc/compiler:compiler": "clang-cl"},+)++config_setting(+ name = "is_windows_msvc",+ constraint_values = ["@platforms//os:windows"],+ flag_values ={"@rules_cc//cc/compiler:compiler": "msvc-cl"}, ) cc_library( @@ -297,7 +320,15 @@ cc_library( }), includes = ["include"], linkopts = select({- "@platforms//os:windows": [+ ":is_windows_clang_mingw": [+ "-lws2_32",+ "-lntdll",+ ],+ ":is_windows_clang_cl": [+ "ws2_32.lib",+ "ntdll.lib",+ ],+ ":is_windows_msvc": [ "ws2_32.lib", "ntdll.lib", ], |
dzbarskyforce-pushed the zbarsky/genrules branch from da162b4 to e0d0ebcCompare
keith approved these changes Dec 11, 2025
Member
keith left a comment
keith left a comment There was a problem hiding this comment.
bazel changes look good, we should give it a bit to see if anyone with more context can review the blake3 changes with
| # See https://llvm.org/LICENSE.txt for license information. | ||
| # SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception | ||
| load("@bazel_lib//lib:run_binary.bzl", "run_binary") |
Collaborator
There was a problem hiding this comment.
CI is failing here. You'll need to add this to MODULE.bazel, or use the version from skylib instead if that's sufficient
ContributorAuthor
There was a problem hiding this comment.
Yep, thanks, addressing!
ContributorAuthor
There was a problem hiding this comment.
the skylib version doesn't support $@ but i'll just expand the output file and use it, not worth a new dep
dzbarskyforce-pushed the zbarsky/genrules branch from e0d0ebc to 9c11c90Comparedzbarskyforce-pushed the zbarsky/genrules branch from 9c11c90 to 917ab4aCompare
dzbarsky commented Dec 13, 2025
| linkopts=select({ | ||
| "@platforms//os:windows": [ | ||
| ":is_windows_clang_mingw": [ | ||
| "-lole32", |
ContributorAuthor
There was a problem hiding this comment.
note ole32 and uuid were missing here but are passed in https://github.com/llvm/llvm-project/blob/fa1dceb67f6fef652c2bf91c070ede64eadc49c6/llvm/lib/Support/CMakeLists.txt#L44C48-L44C53
the other libs are either added by default already or actually unused.
Sign up for freeto join this conversation on GitHub. Already have an account? Sign in to comment
4 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Few things going on here:
genruleis really evil because it bakes the path to the host bash into the command, which fails spectacularly when running on a non-windows remote executor. Swap towrite_file/run_binaryrules to mitigate itWith this set of changes (as well as another one that rewrites
bundle_resources.pyinto C) I am able to hermetically cross-build clang/lld/etc from a windows host to a (mingw) windows target on a linux executor, and use the resulting compilers to compile C binaries/tests (see https://github.com/dzbarsky/toolchains_llvm_bootstrapped/actions/runs/20121686105/job/57743214313?pr=1 and dzbarsky/toolchains_llvm_bootstrapped#1)