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Windows, CROSSTOOL: Add support for clang-cl.exe
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Related bazelbuild#4811

clang-cl is a driver program for clang that attempts to be compatible with MSVC?s cl.exe, which means we can just use MSVC's CROSSTOOL with clang-cl.exe. See more from https://clang.llvm.org/docs/MSVCCompatibility.html

Closes bazelbuild#6553.

Change-Id: I907fc71a51e11c0c204b00c845d14b40e7c9f55f
PiperOrigin-RevId: 219798300
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@meteorcloudy
meteorcloudy authored and Copybara-Service committed Nov 2, 2018
1 parent 4fbeabd commit f445af5
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Showing 2 changed files with 87 additions and 12 deletions.
2 changes: 2 additions & 0 deletions tools/cpp/cc_configure.bzl
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Original file line number Diff line number Diff line change
Expand Up @@ -72,6 +72,8 @@ cc_autoconf = repository_rule(
"BAZEL_USE_LLVM_NATIVE_COVERAGE",
"BAZEL_VC",
"BAZEL_VS",
"BAZEL_LLVM",
"USE_CLANG_CL",
"CC",
"CC_CONFIGURE_DEBUG",
"CC_TOOLCHAIN_NAME",
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97 changes: 85 additions & 12 deletions tools/cpp/windows_cc_configure.bzl
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Original file line number Diff line number Diff line change
Expand Up @@ -152,6 +152,9 @@ def find_vc_path(repository_ctx):
line = line.strip()
if line.startswith(version) and line.find("REG_SZ") != -1:
vc_dir = line[line.find("REG_SZ") + len("REG_SZ"):].strip() + suffix
if vc_dir:
_auto_configure_warning_maybe(repository_ctx, "Visual C++ build tools found at %s" % vc_dir)
return vc_dir

# 4. Check default directories for VC installation
_auto_configure_warning_maybe(repository_ctx, "Looking for default Visual C++ installation directory")
Expand All @@ -169,6 +172,7 @@ def find_vc_path(repository_ctx):
break

if not vc_dir:
_auto_configure_warning_maybe(repository_ctx, "Visual C++ build tools not found.")
return None
_auto_configure_warning_maybe(repository_ctx, "Visual C++ build tools found at %s" % vc_dir)
return vc_dir
Expand Down Expand Up @@ -241,7 +245,7 @@ def find_msvc_tool(repository_ctx, vc_path, tool):
if not repository_ctx.path(tool_path).exists:
return None

return tool_path
return tool_path.replace("\\", "/")

def _find_missing_vc_tools(repository_ctx, vc_path):
"""Check if any required tool is missing under given VC path."""
Expand All @@ -255,12 +259,66 @@ def _find_missing_vc_tools(repository_ctx, vc_path):

return missing_tools

def _is_support_debug_fastlink(repository_ctx, vc_path):
"""Run MSVC linker alone to see if it supports /DEBUG:FASTLINK."""
linker = find_msvc_tool(repository_ctx, vc_path, "link.exe")
def _is_support_debug_fastlink(repository_ctx, linker):
"""Run linker alone to see if it supports /DEBUG:FASTLINK."""
if _use_clang_cl(repository_ctx):
# LLVM's lld-link.exe doesn't support /DEBUG:FASTLINK.
return False
result = execute(repository_ctx, [linker], expect_failure = True)
return result.find("/DEBUG[:{FASTLINK|FULL|NONE}]") != -1

def find_llvm_path(repository_ctx):
"""Find LLVM install path."""

# 1. Check if BAZEL_LLVM is already set by user.
if "BAZEL_LLVM" in repository_ctx.os.environ:
return repository_ctx.os.environ["BAZEL_LLVM"]

_auto_configure_warning_maybe(repository_ctx, "'BAZEL_LLVM' is not set, " +
"start looking for LLVM installation on machine.")

# 2. Look for LLVM installation through registry.
_auto_configure_warning_maybe(repository_ctx, "Looking for LLVM installation through registry")
reg_binary = _get_system_root(repository_ctx) + "\\system32\\reg.exe"
llvm_dir = None
result = repository_ctx.execute([reg_binary, "query", "HKEY_LOCAL_MACHINE\\SOFTWARE\\WOW6432Node\\LLVM\\LLVM"])
_auto_configure_warning_maybe(repository_ctx, "registry query result for LLVM:\n\nSTDOUT(start)\n%s\nSTDOUT(end)\nSTDERR(start):\n%s\nSTDERR(end)\n" %
(result.stdout, result.stderr))
if not result.stderr:
for line in result.stdout.split("\n"):
line = line.strip()
if line.startswith("(Default)") and line.find("REG_SZ") != -1:
llvm_dir = line[line.find("REG_SZ") + len("REG_SZ"):].strip()
if llvm_dir:
_auto_configure_warning_maybe(repository_ctx, "LLVM installation found at %s" % llvm_dir)
return llvm_dir

# 3. Check default directories for LLVM installation
_auto_configure_warning_maybe(repository_ctx, "Looking for default LLVM installation directory")
program_files_dir = get_env_var(repository_ctx, "PROGRAMFILES", default = "C:\\Program Files", enable_warning = True)
path = program_files_dir + "\\LLVM"
if repository_ctx.path(path).exists:
llvm_dir = path

if not llvm_dir:
_auto_configure_warning_maybe(repository_ctx, "LLVM installation not found.")
return None
_auto_configure_warning_maybe(repository_ctx, "LLVM installation found at %s" % llvm_dir)
return llvm_dir

def find_llvm_tool(repository_ctx, llvm_path, tool):
"""Find the exact path of a specific build tool in LLVM. Doesn't %-escape the result."""
tool_path = llvm_path + "\\bin\\" + tool

if not repository_ctx.path(tool_path).exists:
return None

return tool_path.replace("\\", "/")

def _use_clang_cl(repository_ctx):
"""Returns True if USE_CLANG_CL is set to 1."""
return repository_ctx.os.environ.get("USE_CLANG_CL", default = "0") == "1"

def configure_windows_toolchain(repository_ctx):
"""Configure C++ toolchain on Windows."""
paths = resolve_labels(repository_ctx, [
Expand Down Expand Up @@ -338,17 +396,32 @@ def configure_windows_toolchain(repository_ctx):
escaped_tmp_dir = escape_string(
get_env_var(repository_ctx, "TMP", "C:\\Windows\\Temp").replace("\\", "\\\\"),
)
msvc_cl_path = find_msvc_tool(repository_ctx, vc_path, "cl.exe").replace("\\", "/")
msvc_ml_path = find_msvc_tool(repository_ctx, vc_path, "ml64.exe").replace("\\", "/")
msvc_link_path = find_msvc_tool(repository_ctx, vc_path, "link.exe").replace("\\", "/")
msvc_lib_path = find_msvc_tool(repository_ctx, vc_path, "lib.exe").replace("\\", "/")

llvm_path = ""
if _use_clang_cl(repository_ctx):
llvm_path = find_llvm_path(repository_ctx)
if not llvm_path:
auto_configure_fail("\nUSE_CLANG_CL is set to 1, but Bazel cannot find Clang installation on your system.\n" +
"Please install Clang via http://releases.llvm.org/download.html\n")
cl_path = find_llvm_tool(repository_ctx, llvm_path, "clang-cl.exe")
link_path = find_llvm_tool(repository_ctx, llvm_path, "lld-link.exe")
lib_path = find_llvm_tool(repository_ctx, llvm_path, "llvm-lib.exe")
else:
cl_path = find_msvc_tool(repository_ctx, vc_path, "cl.exe")
link_path = find_msvc_tool(repository_ctx, vc_path, "link.exe")
lib_path = find_msvc_tool(repository_ctx, vc_path, "lib.exe")

msvc_ml_path = find_msvc_tool(repository_ctx, vc_path, "ml64.exe")
escaped_cxx_include_directories = []

for path in escaped_include_paths.split(";"):
if path:
escaped_cxx_include_directories.append("cxx_builtin_include_directory: \"%s\"" % path)
if llvm_path:
clang_include_path = (llvm_path + "\\lib\\clang").replace("\\", "\\\\")
escaped_cxx_include_directories.append("cxx_builtin_include_directory: \"%s\"" % clang_include_path)

support_debug_fastlink = _is_support_debug_fastlink(repository_ctx, vc_path)
support_debug_fastlink = _is_support_debug_fastlink(repository_ctx, link_path)

repository_ctx.template(
"CROSSTOOL",
Expand All @@ -361,10 +434,10 @@ def configure_windows_toolchain(repository_ctx):
"%{msvc_env_path}": escaped_paths,
"%{msvc_env_include}": escaped_include_paths,
"%{msvc_env_lib}": escaped_lib_paths,
"%{msvc_cl_path}": msvc_cl_path,
"%{msvc_cl_path}": cl_path,
"%{msvc_ml_path}": msvc_ml_path,
"%{msvc_link_path}": msvc_link_path,
"%{msvc_lib_path}": msvc_lib_path,
"%{msvc_link_path}": link_path,
"%{msvc_lib_path}": lib_path,
"%{dbg_mode_debug}": "/DEBUG:FULL" if support_debug_fastlink else "/DEBUG",
"%{fastbuild_mode_debug}": "/DEBUG:FASTLINK" if support_debug_fastlink else "/DEBUG",
"%{content}": _get_escaped_windows_msys_crosstool_content(repository_ctx),
Expand Down

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