Setup build for static/dynamic LLVM distributions (#6)

* Setup build for static/dynamic LLVM distributions
* Detect LLVM build type automatically

Add a switch for using static or dynamic LLVM libraries. Depending on how liblldb.so is linked, we also need to use different setups.

Author: werat

.bazelrc

@@ -1,3 +1,6 @@
+# Try loading per-user configuration.
+try-import %workspace%/user.bazelrc
+
 # On Windows clang.exe tries to find the MSVC toolchain by looking at environmental variables,
 # querying Visual Studio instances via COM (>=2017) and reading Registry keys (<=2015).
 # ProgramData data is typically required for COM api querying, unless a custom location for

.github/workflows/main.yml

@@ -14,19 +14,19 @@ jobs:
         tag: [10, 11]
     env:
       LLVM_INSTALL_PATH: /usr/lib/llvm-${{ matrix.tag }}
-  
+
     steps:
       - uses: actions/checkout@v2
-      
+
       - name: Setup LLVM-${{ matrix.tag }}
         run: |
           wget https://apt.llvm.org/llvm.sh
           chmod +x ./llvm.sh
           sudo ./llvm.sh ${{ matrix.tag }}
           sudo apt install -y llvm-${{ matrix.tag }}-dev libclang-${{ matrix.tag }}-dev liblldb-${{ matrix.tag }}-dev
-      
+
       - name: Build
         run: bazel build :all
-      
+
       - name: Test
         run: bazel test --test_output=errors :all

.gitignore

@@ -3,6 +3,7 @@
 
 # Bazel directories/symlinks
 bazel-*
+user.bazelrc
 
 # YouCompleteMe
 .ycm_extra_conf.py

BUILD

@@ -110,14 +110,8 @@ cc_library(
     data = [
         "//testdata:test_binary_gen",
         "//testdata:test_binary_srcs",
-    ] + select({
-        "@bazel_tools//src/conditions:windows": [
-            # There is no lldb-server on Windows.
-        ],
-        "//conditions:default": [
-            "@llvm_project_local//:lldb-server",
-        ],
-    }),
+        "@llvm_project_local//:lldb-server",
+    ],
     deps = [
         "@bazel_tools//tools/cpp/runfiles",
         "@llvm_project_local//:lldb-api",

README.md

@@ -91,6 +91,15 @@ bazel test :all
 bazel run :main -- "(1 + 2) * 42 / 4"
 ```
 
+Depending on your distribution of LLVM, you may need to provide
+`--@llvm_project_local//:llvm_build={static,dynamic}` flag. For example, if your
+`liblldb.so` is linked dynamically (this is the case when installing via `apt`),
+then you need to use `llvm_build=dynamic`. The build script [tries to choose the
+correct default value automatically](/build_defs/repo_rules.bzl#L21), but it can
+be wrong in some situations (please, report and contribute 🙂).
+
+> **Hint:** You can add this option to your `user.bazelrc`.
+
 ## Disclamer
 
 This is not an officially supported Google product.

WORKSPACE

@@ -2,11 +2,20 @@ workspace(name = "lldb_eval")
 
 load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
 
+http_archive(
+    name = "bazel_skylib",
+    sha256 = "1c531376ac7e5a180e0237938a2536de0c54d93f5c278634818e0efc952dd56c",
+    urls = [
+        "https://github.com/bazelbuild/bazel-skylib/releases/download/1.0.3/bazel-skylib-1.0.3.tar.gz",
+        "https://mirror.bazel.build/github.com/bazelbuild/bazel-skylib/releases/download/1.0.3/bazel-skylib-1.0.3.tar.gz",
+    ],
+)
+
 http_archive(
     name = "com_google_googletest",
-    sha256 = "ff7a82736e158c077e76188232eac77913a15dac0b22508c390ab3f88e6d6d86",
-    strip_prefix = "googletest-b6cd405286ed8635ece71c72f118e659f4ade3fb",
-    urls = ["https://github.com/google/googletest/archive/b6cd405286ed8635ece71c72f118e659f4ade3fb.zip"],  # 2019-01-07
+    sha256 = "94c634d499558a76fa649edb13721dce6e98fb1e7018dfaeba3cd7a083945e91",
+    strip_prefix = "googletest-release-1.10.0",
+    urls = ["https://github.com/google/googletest/archive/release-1.10.0.zip"],
 )
 
 load("//build_defs:repo_rules.bzl", "llvm_project_configure")

build_defs/llvm_project_local.BUILD

@@ -1,7 +1,44 @@
+load("@bazel_skylib//lib:selects.bzl", "selects")
+load("@bazel_skylib//rules:common_settings.bzl", "string_flag")
 load("@rules_cc//cc:defs.bzl", "cc_library")
 
 package(default_visibility = ["//visibility:public"])
 
+string_flag(
+    name = "llvm_build",
+    build_setting_default = "{LLVM_BUILD_DEFAULT}",
+    values = [
+        "static",
+        "dynamic",
+    ],
+)
+
+config_setting(
+    name = "llvm_build_static",
+    flag_values = {":llvm_build": "static"},
+)
+
+config_setting(
+    name = "llvm_build_dynamic",
+    flag_values = {":llvm_build": "dynamic"},
+)
+
+selects.config_setting_group(
+    name = "linux_dynamic",
+    match_all = [
+        "@bazel_tools//src/conditions:linux_x86_64",
+        ":llvm_build_dynamic",
+    ],
+)
+
+selects.config_setting_group(
+    name = "linux_static",
+    match_all = [
+        "@bazel_tools//src/conditions:linux_x86_64",
+        ":llvm_build_static",
+    ],
+)
+
 LLVM_LINKOPTS = select({
     "@bazel_tools//src/conditions:windows": [],
     "//conditions:default": [
@@ -68,6 +105,17 @@ filegroup(
     ]),
 )
 
+filegroup(
+    name = "libllvm-so",
+    srcs = select({
+        "@bazel_tools//src/conditions:windows": [
+        ],
+        "//conditions:default": glob([
+            "lib/libLLVM*.so*",
+        ]),
+    }),
+)
+
 filegroup(
     name = "clang-headers",
     srcs = glob([
@@ -80,21 +128,36 @@ filegroup(
     ]),
 )
 
+filegroup(
+    name = "libclang-cpp-so",
+    srcs = select({
+        "@bazel_tools//src/conditions:windows": [
+        ],
+        "//conditions:default": glob([
+            "lib/libclang-cpp*.so*",
+        ]),
+    }),
+)
+
 cc_library(
     name = "llvm-support",
     srcs = select({
         "@bazel_tools//src/conditions:windows": [
             "lib/LLVMSupport.lib",
             "lib/LLVMDemangle.lib",
         ],
-        "//conditions:default": [
+        ":linux_dynamic": [
+            ":libllvm-so",
+        ],
+        ":linux_static": [
             "lib/libLLVMSupport.a",
             "lib/libLLVMDemangle.a",
         ],
     }),
     hdrs = [":llvm-headers"],
     includes = ["include"],
     linkopts = LLVM_LINKOPTS,
+    linkstatic = 1,
 )
 
 cc_library(
@@ -107,8 +170,10 @@ cc_library(
             "lib/LLVMBitstreamReader.lib",
             "lib/LLVMBinaryFormat.lib",
         ],
-        "//conditions:default": [
-            # $(llvm-config --libs mc core support)
+        ":linux_dynamic": [
+            ":libllvm-so",
+        ],
+        ":linux_static": [
             "lib/libLLVMCore.a",
             "lib/libLLVMRemarks.a",
             "lib/libLLVMBitstreamReader.a",
@@ -117,6 +182,7 @@ cc_library(
     }),
     hdrs = [":llvm-headers"],
     includes = ["include"],
+    linkstatic = 1,
     deps = [":llvm-support"],
 )
 
@@ -128,33 +194,27 @@ cc_library(
             "lib/LLVMDebugInfoCodeView.lib",
             "lib/LLVMDebugInfoMSF.lib",
         ],
-        "//conditions:default": [
+        ":linux_dynamic": [
+            ":libllvm-so",
+        ],
+        ":linux_static": [
             "lib/libLLVMMC.a",
             "lib/libLLVMDebugInfoCodeView.a",
             "lib/libLLVMDebugInfoMSF.a",
         ],
     }),
     hdrs = [":llvm-headers"],
     includes = ["include"],
+    linkstatic = 1,
     deps = [":llvm-core"],
 )
 
 cc_library(
     name = "llvm-shared",
-    srcs = select({
-        "@bazel_tools//src/conditions:windows": [
-        ],
-        "//conditions:default": glob([
-            "lib/libLLVM*.so",
-        ]),
-    }),
+    srcs = [":libllvm-so"],
     hdrs = [":llvm-headers"],
     includes = ["include"],
-    deps = [
-        ":llvm-core",
-        ":llvm-mc",
-        ":llvm-support",
-    ],
+    linkstatic = 1,
 )
 
 cc_library(
@@ -163,12 +223,16 @@ cc_library(
         "@bazel_tools//src/conditions:windows": [
             "lib/clangBasic.lib",
         ],
-        "//conditions:default": [
+        ":linux_dynamic": [
+            ":libclang-cpp-so",
+        ],
+        ":linux_static": [
             "lib/libclangBasic.a",
         ],
     }),
     hdrs = [":clang-headers"],
     includes = ["include"],
+    linkstatic = 1,
     deps = [
         ":llvm-core",
         ":llvm-mc",
@@ -182,18 +246,30 @@ cc_library(
         "@bazel_tools//src/conditions:windows": [
             "lib/clangLex.lib",
         ],
-        "//conditions:default": [
+        ":linux_dynamic": glob([
+            "lib/libclang-cpp*.so*",
+        ]),
+        ":linux_static": [
             "lib/libclangLex.a",
         ],
     }),
     hdrs = [":clang-headers"],
     includes = ["include"],
+    linkstatic = 1,
     deps = [
         ":clang-basic",
         ":llvm-support",
     ],
 )
 
+cc_library(
+    name = "clangcpp-shared",
+    srcs = [":libclang-cpp-so"],
+    hdrs = [":clang-headers"],
+    includes = ["include"],
+    linkstatic = 1,
+)
+
 cc_library(
     name = "lldb-api",
     srcs = select({
@@ -211,8 +287,13 @@ cc_library(
         "include/lldb/**/*.inc",
     ]),
     includes = ["include"],
-    deps = [
-        ":llvm-shared",  # liblldb can be dynamically linked and depend on libLLVM.
-        ":llvm-support",
-    ],
+    deps = select({
+        ":llvm_build_dynamic": [
+            ":llvm-shared",
+            ":clangcpp-shared",
+        ],
+        ":llvm_build_static": [
+            # Don't have any dependencies if linked statically.
+        ],
+    }),
 )

build_defs/repo_rules.bzl

@@ -16,6 +16,25 @@
 This module configures a local repository for an llvm-project.
 """
 
+load("@bazel_skylib//lib:paths.bzl", "paths")
+
+def _get_llvm_build_type(ctx, llvm_path):
+    if ctx.os.name.startswith("windows"):
+        # There are no prebuilt binaries for Windows, so always assume static.
+        return "static"
+
+    ldd = ctx.which("ldd")
+    if ldd == None:
+        # No `ldd`, can't do without it.
+        return "static"
+
+    # Execute `ldd liblldb.so` to figure out whether it depends on libLLVM.so.
+    result = ctx.execute([ldd, paths.join(llvm_path, "lib", "liblldb.so")])
+    if result.stdout.find("libLLVM") != -1:
+        return "dynamic"
+
+    return "static"
+
 def _impl(repository_ctx):
     llvm_path = repository_ctx.os.environ.get("LLVM_INSTALL_PATH")
     if llvm_path == None:
@@ -24,15 +43,21 @@ def _impl(repository_ctx):
             "with LLVM {bin,lib,include} directories. E.g. \"/usr/lib/llvm\".",
         )
 
-    repository_ctx.symlink(llvm_path + "/bin", "bin")
-    repository_ctx.symlink(llvm_path + "/lib", "lib")
-    repository_ctx.symlink(llvm_path + "/include", "include")
+    # Try to guess a default value for :llvm_build flag. It should be "dynamic"
+    # if liblldb.so is built dynamically and "static" otherwise.
+    llvm_build = _get_llvm_build_type(repository_ctx, llvm_path)
+
+    repository_ctx.symlink(paths.join(llvm_path, "bin"), "bin")
+    repository_ctx.symlink(paths.join(llvm_path, "lib"), "lib")
+    repository_ctx.symlink(paths.join(llvm_path, "include"), "include")
     repository_ctx.template(
         "BUILD",
         Label("//build_defs:llvm_project_local.BUILD"),
+        substitutions = {"{LLVM_BUILD_DEFAULT}": llvm_build},
     )
 
 llvm_project_configure = repository_rule(
     implementation = _impl,
     environ = ["LLVM_INSTALL_PATH"],
+    local = True,
 )

tools/BUILD

@@ -46,17 +46,11 @@ cc_binary(
     data = [
         "//testdata:fuzzer_binary_gen",
         "//testdata:fuzzer_binary_srcs",
-    ] + select({
-        "@bazel_tools//src/conditions:windows": [
-            # There is no lldb-server on Windows.
-        ],
-        "//conditions:default": [
-            "@llvm_project_local//:lldb-server",
-        ],
-    }),
+        "@llvm_project_local//:lldb-server",
+    ],
     deps = [
+        ":fuzzer_lib",
         "//:lldb-eval",
-        "//tools:fuzzer_lib",
         "@bazel_tools//tools/cpp/runfiles",
         "@llvm_project_local//:lldb-api",
     ],