[Bazel] Introduce `//compiler-rt:profile`

[chapuni]

Summary

At the moment, provide only profile at first.

[MaskRay]

utils/bazel/llvm-project-overlay/compiler-rt/BUILD.bazel

17

Windows doesn't define COMPILER_RT_HAS_FCNTL_LCK or COMPILER_RT_HAS_UNAME

25

We need lib/profile/*.cpp for InstrProfilingRuntime.cpp

38

Are the two -Wno- needed?

[aeubanks]

utils/bazel/llvm-project-overlay/compiler-rt/BUILD.bazel

38

should just fix the sources instead if these are finding real issues

[aaronmondal]

FYI I have buildfiles for a bunch of the compiler-rt targets at https://github.com/eomii/rules_ll/blob/main/llvm-project-overlay/compiler-rt/lib/profile/BUILD.bazel

I'd a bit hesitant to build those with the potentially very old host toolchain since these targets are linked into non clang-toolchain executables. For something like profiling this might not be as impactful as building libcxx with an old toolchain but I'm a bit worried that this could lead to issues when using bootstrapped toolchains.

[paquette]

utils/bazel/llvm-project-overlay/compiler-rt/BUILD.bazel

28

why is this excluded?

https://github.com/llvm/llvm-project/blob/c8bcc48af628d9f1e6b0cfd3edda330f3c04ed9a/compiler-rt/lib/profile/InstrProfilingFile.c#L21

It looks like this is necessary for continuous mode on Windows?

38

+1

[chapuni]

Thanks for feedbacks.

In D156095#4529073, @aaronmondal wrote:

FYI I have buildfiles for a bunch of the compiler-rt targets at https://github.com/eomii/rules_ll/blob/main/llvm-project-overlay/compiler-rt/lib/profile/BUILD.bazel

I'd a bit hesitant to build those with the potentially very old host toolchain since these targets are linked into non clang-toolchain executables. For something like profiling this might not be as impactful as building libcxx with an old toolchain but I'm a bit worried that this could lead to issues when using bootstrapped toolchains.

I assume the host toolchain should be capable of building runtimes for bootstrapping.

[RFC] RUNTIMES may be built in-tree and be linked to tools
https://discourse.llvm.org/t/rfc-runtimes-may-be-built-in-tree-and-be-linked-to-tools/70357

rules_ll itself is interesting. I will read and play it later. Thanks.

utils/bazel/llvm-project-overlay/compiler-rt/BUILD.bazel

17

I haven't introduced conditions since I don't use other environments. Do you think I could use select() with minimal conditions here? Could we conditionalize defs individually?

25

I missed it. Thanks. I have confirmed it can be built (and identical to CMake's in my environment).

38

-Wno-strict-prototypes was redundant. It has been there since I checked -std=c11 for strdup.

-Wno-pedantic is required since my environment enforces -pedantic. I know compiler-rt doesn't like -pedantic. I will remove -pedantic in my environment.

[paquette]

utils/bazel/llvm-project-overlay/compiler-rt/BUILD.bazel

17

Looks like CMake checks if the target supports fcntl, atomics, ..., and then sets COMPILER_RT_HAS_<whatever> accordingly.

For example:

https://github.com/llvm/llvm-project/blob/c8bcc48af628d9f1e6b0cfd3edda330f3c04ed9a/compiler-rt/lib/profile/CMakeLists.txt#L99

[chapuni]

I don't have any environments for targeting Win32 at the moment.
Do we think I should make this Win32-compatible?

utils/bazel/llvm-project-overlay/compiler-rt/BUILD.bazel

28

It is excluded for non-Win32 targets also in CMake.

[chapuni]

utils/bazel/llvm-project-overlay/compiler-rt/BUILD.bazel

17

AFAIK LLVM's Bazel build is less configurable. So I think something may rely on assumptions.
See also config.bzl and llvm/Config/config.h

[chapuni]

• Add *.cpp to srcs
• Remove copts

[chapuni]

utils/bazel/llvm-project-overlay/compiler-rt/BUILD.bazel

38

copts may be pruned if -pedantic is not given.

[paquette]

In D156095#4530373, @chapuni wrote:

I don't have any environments for targeting Win32 at the moment.
Do we think I should make this Win32-compatible?

I think we should either

1. Support Windows.

OR

2. Emit a useful error ("Building libprofile on Windows using Bazel not yet supported") if we can't yet support Windows.

[chapuni]

• Will invoke error unless the platform is linux

[chapuni]

At the moment, this can be built for targeting linux, or will raise error before building begins.

The error cannot be seen unless //compiler-rt:profile is specified as a target explicitly.

[paquette]

I think this looks good. @MaskRay WDYT?

[chapuni]

utils/bazel/llvm-project-overlay/compiler-rt/BUILD.bazel

35–36

Seems wrong format. I'll fix it later.

[chapuni]

• Reformat.

utils/bazel/llvm-project-overlay/compiler-rt/BUILD.bazel

+# This file is licensed under the Apache License v2.0 with LLVM Exceptions.
+# See https://llvm.org/LICENSE.txt for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+package(
+    default_visibility = ["//visibility:public"],
+    features = ["layering_check"],
+)
+
+licenses(["notice"])
+
+cc_library(
+    name = "config",
+    defines = select({
+        "@platforms//os:linux": [
+            "COMPILER_RT_HAS_ATOMICS=1",
+            "COMPILER_RT_HAS_FCNTL_LCK=1",
+            "COMPILER_RT_HAS_UNAME=1",
+        ],
+        # Will raise error unless supported platforms.
+    }),
+)
+
+WIN32_ONLY_FILES = [
+    "lib/profile/WindowsMMap.c",
+]
+
+cc_library(
+    name = "profile",
+    srcs = glob(
+        [
+            "lib/profile/*.c",
+            "lib/profile/*.cpp",
+            "lib/profile/*.h",
+        ],
+        exclude = WIN32_ONLY_FILES,
+    ) + select({
+        "@platforms//os:windows": WIN32_ONLY_FILES,
+        "//conditions:default": []
+    }),
+    hdrs = glob([
+        "include/profile/*.inc",
+    ]),
+    includes = [
+        "include",
+    ],
+    deps = [
+        ":config",
+    ],
+    linkstatic = True,
+)