Sync with GRAIL's toolchain configuration

Author: Siddhartha Bagaria

README.md

@@ -31,29 +31,30 @@ Notes:
 
 - The LLVM toolchain archive is downloaded and extracted in the named
   repository.  People elsewhere have used wrapper scripts to avoid symlinking
-and get better control of the environment in which the toolchain binaries are
-run.
+  and get better control of the environment in which the toolchain binaries are
+  run.
 
 - Sandboxing the toolchain introduces a significant overhead (100ms per
-  action). To overcome this, one can use `--experimental_sandbox_fs=/dev/shm`.
-However, not all environments might have enough shared memory available to load
-all the files in memory. In order to avoid sandboxing the toolchain entirely,
-we can use absolute paths. When running bazel actions, these paths will be
-available from inside the sandbox as part of the / read-only mount.
+  action). To overcome this, one can use
+  `--experimental_sandbox_base=/dev/shm`.  However, not all environments might
+  have enough shared memory available to load all the files in memory. That is
+  why we have templated the paths to the toolchain as absolute paths. When
+  running bazel actions, these paths will be available from inside the sandbox
+  as part of the / read-only mount.
 
-- While the C++ toolchain itself works well with relative paths (except the
-  performance hit because of sandboxing), the go toolchain needs the linker and
-the linked libraries as absolute. This is a limitation of the cpp configuration
-fragment provided by skylark and used by the go toolchain.
+- The toolchain is known to also work with `rules_go`, both with absolute and
+  relative paths.
 
 - There is no R toolchain yet, so the Makevars file has been repurposed to
-  provide the right configuration, but only when the configure script for
-packages do not override the variables set in the Makevars.
+  provide the right configuration, but only when using `cc_deps` attribute of
+  `r_pkg`. All packages not using `cc_deps` are free to configure themselves.
+  The Makevars file provided will always use absolute paths. This implies that
+  the build actions are not reproducible across multiple workspaces, although
+  the build outputs can be.
 
 - The toolchain is almost hermetic but borrows system headers and libraries
-  from the user's system. If needed, one can package a sysroot for their build
-environment and set `builtin_sysroot` in CROSSTOOL. If using relative paths, be
-sure to add your sysroot files to the `all_files` attribute of the toolchain.
+  from the user's system. If needed, we can package a sysroot for our build
+  environment and set `builtin_sysroot` in CROSSTOOL.
 
 Other examples of toolchain configuration:
 

toolchain/BUILD.tpl

@@ -23,7 +23,7 @@ filegroup(
 
 filegroup(
     name = "cc_wrapper",
-    srcs = ["cc_wrapper.sh"],
+    srcs = ["bin/cc_wrapper.sh"],
 )
 
 cc_toolchain_suite(
@@ -39,6 +39,9 @@ load("@com_grail_bazel_toolchain//toolchain:configure.bzl", "conditional_cc_tool
 conditional_cc_toolchain("cc-clang-linux", "k8", False, %{absolute_paths})
 conditional_cc_toolchain("cc-clang-darwin", "darwin", True, %{absolute_paths})
 
+## LLVM toolchain files
+# Needed when not using absolute paths.
+
 filegroup(
     name = "clang",
     srcs = [
@@ -52,25 +55,32 @@ filegroup(
     name = "ld",
     srcs = [
         "bin/ld.lld",
-        "bin/ld64.lld"
+        "bin/ld",
+        "bin/ld.gold",  # Dummy file on non-linux.
     ],
 )
 
 filegroup(
     name = "include",
     srcs = glob([
         "include/c++/**",
-        "lib/clang/*/include/**",
+        "lib/clang/%{llvm_version}/include/**",
     ]),
 )
 
 filegroup(
     name = "lib",
-    srcs = [
-        "lib/libc++.a",
-        "lib/libc++abi.a",
-        "lib/libunwind.a",
-    ],
+    srcs = glob(
+        [
+            "lib/lib*.a",
+            "lib/clang/%{llvm_version}/lib/**/*.a",
+        ],
+        exclude = [
+            "lib/libLLVM*.a",
+            "lib/libclang*.a",
+            "lib/liblld*.a",
+        ],
+    ),
 )
 
 filegroup(
@@ -128,18 +138,7 @@ filegroup(
 
 filegroup(
     name = "binutils_components",
-    srcs = [
-        ":ar",
-        ":as",
-        ":dwp",
-        ":ld",
-        ":nm",
-        ":objcopy",
-        ":objdump",
-        ":profdata",
-        ":ranlib",
-        ":readelf",
-    ],
+    srcs = glob(["bin/*"]),
 )
 
 filegroup(

toolchain/CROSSTOOL.tpl

@@ -33,12 +33,12 @@ toolchain {
   compiler: "clang"
   host_system_name: "local"
   needsPic: true
-  supports_gold_linker: false
   supports_incremental_linker: false
   supports_fission: false
   supports_interface_shared_objects: false
   supports_normalizing_ar: false
   supports_start_end_lib: true
+  supports_gold_linker: true
   target_libc: "local"
   target_cpu: "k8"
   target_system_name: "local"
@@ -54,6 +54,7 @@ toolchain {
   unfiltered_cxx_flag: "-D__DATE__=\"redacted\""
   unfiltered_cxx_flag: "-D__TIMESTAMP__=\"redacted\""
   unfiltered_cxx_flag: "-D__TIME__=\"redacted\""
+  unfiltered_cxx_flag: "-fdebug-prefix-map=%{toolchain_path_prefix}=%{debug_toolchain_path_prefix}"
 
   # Security
   compiler_flag: "-U_FORTIFY_SOURCE"
@@ -65,20 +66,20 @@ toolchain {
   compiler_flag: "-Wall"
 
   # C++
-  cxx_flag: "-std=c++11"
+  cxx_flag: "-std=c++17"
   cxx_flag: "-stdlib=libc++"
   # The linker has no way of knowing if there are C++ objects; so we always link C++ libraries.
-  linker_flag: "%{toolchain_path_prefix}lib/libc++.a"
-  linker_flag: "%{toolchain_path_prefix}lib/libc++abi.a"
-  linker_flag: "%{toolchain_path_prefix}lib/libunwind.a"
+  linker_flag: "-l:libc++.a"
+  linker_flag: "-l:libc++abi.a"
+  linker_flag: "-l:libunwind.a"
   cxx_flag: "-DLIBCXX_USE_COMPILER_RT=YES"
   linker_flag: "-rtlib=compiler-rt"
-  linker_flag: "-lpthread"
-  linker_flag: "-ldl" # For libunwind
+  linker_flag: "-lpthread"  # For libunwind
+  linker_flag: "-ldl"  # For libunwind
 
   # Linker
   linker_flag: "-lm"
-  linker_flag: "-fuse-ld=lld"
+  linker_flag: "-fuse-ld=gold"
   linker_flag: "-Wl,--build-id=md5"
   linker_flag: "-Wl,--hash-style=gnu"
 
@@ -89,14 +90,11 @@ toolchain {
   cxx_builtin_include_directory: "/include"
   cxx_builtin_include_directory: "/usr/include"
   cxx_builtin_include_directory: "/usr/local/include"
-  compiler_flag: "-isystem%{toolchain_path_prefix}include/c++/v1"
-  compiler_flag: "-isystem%{toolchain_path_prefix}lib/clang/%{llvm_version}/include"
 
   objcopy_embed_flag: "-I"
   objcopy_embed_flag: "binary"
 
-  compiler_flag: "-B%{toolchain_path_prefix}bin"
-  tool_path {name: "ld" path: "%{tools_path_prefix}bin/ld.lld" }
+  tool_path {name: "ld" path: "%{tools_path_prefix}bin/ld.gold" }  # TODO: Switch to lld after https://reviews.llvm.org/D41978
   tool_path {name: "cpp" path: "%{tools_path_prefix}bin/clang-cpp" }
   tool_path {name: "dwp" path: "%{tools_path_prefix}bin/llvm-dwp" }
   tool_path {name: "gcov" path: "%{tools_path_prefix}bin/llvm-profdata" }
@@ -124,60 +122,6 @@ toolchain {
   }
 
   linking_mode_flags { mode: DYNAMIC }
-
-  feature {
-    name: "coverage"
-  }
-  feature {
-    name: "llvm_coverage_map_format"
-    flag_set {
-      action: "preprocess-assemble"
-      action: "c-compile"
-      action: "c++-compile"
-      action: "c++-module-compile"
-      flag_group {
-        flag: "-fprofile-instr-generate"
-        flag: "-fcoverage-mapping"
-        flag: "-g"
-      }
-    }
-    flag_set {
-      action: "c++-link-dynamic-library"
-      action: "c++-link-nodeps-dynamic-library"
-      action: "c++-link-executable"
-      flag_group {
-        flag: "-fprofile-instr-generate"
-      }
-    }
-    requires {
-      feature: "coverage"
-    }
-  }
-  feature {
-    name: "gcc_coverage_map_format"
-    flag_set {
-      action: "preprocess-assemble"
-      action: "c-compile"
-      action: "c++-compile"
-      action: "c++-module-compile"
-      flag_group {
-        flag: "-fprofile-arcs"
-        flag: "-ftest-coverage"
-        flag: "-g"
-      }
-    }
-    flag_set {
-      action: "c++-link-dynamic-library"
-      action: "c++-link-nodeps-dynamic-library"
-      action: "c++-link-executable"
-      flag_group {
-        flag: "-lgcov"
-      }
-    }
-    requires {
-      feature: "coverage"
-    }
-  }
 }
 
 toolchain {
@@ -189,7 +133,7 @@ toolchain {
   compiler: "clang"
   abi_version: "darwin_x86_64"
   abi_libc_version: "darwin_x86_64"
-  needsPic: true
+  needsPic: false
 
   builtin_sysroot: ""
 
@@ -202,6 +146,7 @@ toolchain {
   unfiltered_cxx_flag: "-D__DATE__=\"redacted\""
   unfiltered_cxx_flag: "-D__TIMESTAMP__=\"redacted\""
   unfiltered_cxx_flag: "-D__TIME__=\"redacted\""
+  unfiltered_cxx_flag: "-fdebug-prefix-map=%{toolchain_path_prefix}=%{debug_toolchain_path_prefix}"
 
   # Security
   compiler_flag: "-D_FORTIFY_SOURCE=1"
@@ -215,16 +160,11 @@ toolchain {
   compiler_flag: "-Wall"
 
   # C++
-  cxx_flag: "-std=c++11"
+  cxx_flag: "-std=c++17"
   cxx_flag: "-stdlib=libc++"
   # The linker has no way of knowing if there are C++ objects; so we always link C++ libraries.
-  linker_flag: "%{toolchain_path_prefix}lib/libc++.a"
-  linker_flag: "%{toolchain_path_prefix}lib/libc++abi.a"
-  linker_flag: "%{toolchain_path_prefix}lib/libunwind.a"
-  cxx_flag: "-DLIBCXX_USE_COMPILER_RT=YES"
-  linker_flag: "-rtlib=compiler-rt"
-  linker_flag: "-lpthread"
-  linker_flag: "-ldl" # For libunwind
+  linker_flag: "-lc++"
+  linker_flag: "-lc++abi"
 
   # Linker
   linker_flag: "-lm"
@@ -235,27 +175,22 @@ toolchain {
   cxx_builtin_include_directory: "%{toolchain_path_prefix}include/c++/v1"
   cxx_builtin_include_directory: "%{toolchain_path_prefix}lib/clang/%{llvm_version}/include"
   cxx_builtin_include_directory: "/usr/include"
-  cxx_builtin_include_directory: "/usr/include/linux"
   cxx_builtin_include_directory: "/System/Library/Frameworks"
   cxx_builtin_include_directory: "/Library/Frameworks"
-  #cxx_builtin_include_directory: "/Applications/Xcode.app/Contents/Developer"
-  compiler_flag: "-isystem%{toolchain_path_prefix}include/c++/v1"
-  compiler_flag: "-isystem%{toolchain_path_prefix}lib/clang/%{llvm_version}/include"
 
   objcopy_embed_flag: "-I"
   objcopy_embed_flag: "binary"
 
-  compiler_flag: "-B%{toolchain_path_prefix}bin"
-  tool_path {name: "ld" path: "/usr/bin/ld" }  # lld is not ready for macOS.
+  tool_path {name: "ld" path: "%{tools_path_prefix}bin/ld" }  # lld is not ready for macOS.
   tool_path {name: "cpp" path: "%{tools_path_prefix}bin/clang-cpp" }
   tool_path {name: "dwp" path: "%{tools_path_prefix}bin/llvm-dwp" }
   tool_path {name: "gcov" path: "%{tools_path_prefix}bin/llvm-profdata" }
   tool_path {name: "nm" path: "%{tools_path_prefix}bin/llvm-nm" }
   tool_path {name: "objcopy" path: "%{tools_path_prefix}bin/llvm-objcopy" }
   tool_path {name: "objdump" path: "%{tools_path_prefix}bin/llvm-objdump" }
   tool_path {name: "strip" path: "/usr/bin/strip" }
-  tool_path {name: "gcc" path: "%{tools_path_prefix}cc_wrapper.sh" }
-  tool_path {name: "ar" path: "/usr/bin/libtool" }  # default archiver flags configuration is different for macOS.
+  tool_path {name: "gcc" path: "%{tools_path_prefix}bin/cc_wrapper.sh" }
+  tool_path {name: "ar" path: "/usr/bin/libtool" }  # system provided libtool is preferred.
 
   compilation_mode_flags {
     mode: FASTBUILD
@@ -304,64 +239,4 @@ toolchain {
       }
     }
   }
-
-  feature {
-    name: "coverage"
-  }
-  feature {
-    name: "llvm_coverage_map_format"
-    flag_set {
-      action: "preprocess-assemble"
-      action: "c-compile"
-      action: "c++-compile"
-      action: "c++-module-compile"
-      action: "objc-compile"
-      action: "objc++-compile"
-      flag_group {
-        flag: "-fprofile-instr-generate"
-        flag: "-fcoverage-mapping"
-        flag: "-g"
-      }
-    }
-    flag_set {
-      action: "c++-link-dynamic-library"
-      action: "c++-link-nodeps-dynamic-library"
-      action: "c++-link-executable"
-      action: "objc-executable"
-      action: "objc++-executable"
-      flag_group {
-        flag: "-fprofile-instr-generate"
-      }
-    }
-    requires {
-      feature: "coverage"
-    }
-  }
-  feature {
-    name: "gcc_coverage_map_format"
-    flag_set {
-      action: "preprocess-assemble"
-      action: "c-compile"
-      action: "c++-compile"
-      action: "c++-module-compile"
-      action: "objc-compile"
-      action: "objc++-compile"
-      flag_group {
-        flag: "-fprofile-arcs"
-        flag: "-ftest-coverage"
-        flag: "-g"
-      }
-    }
-    flag_set {
-      action: "c++-link-dynamic-library"
-      action: "c++-link-nodeps-dynamic-library"
-      action: "c++-link-executable"
-      flag_group {
-        flag: "-lgcov"
-      }
-    }
-    requires {
-      feature: "coverage"
-    }
-  }
 }