| commit | a5c58bc5f684887d671b0c388ff5e42be88584c4 | [log] [tgz] |
|---|---|---|
| author | Than McIntosh <thanm@google.com> | Thu May 03 08:32:06 2018 -0400 |
| committer | Than McIntosh <thanm@google.com> | Thu May 10 18:43:01 2018 +0000 |
| tree | 5c72af712d24c95836f8e958c759aa9cd1817bf1 | |
| parent | c6cb56a67fd000207a964c5dffc517ddeff63011 [diff] |
gollvm: add cmake controls for go compiler dependence In typical use cases, we want to cmake to force a rebuild of all objects built from Go source if the compiler binary changes For compiler developers, however, this dependence can be a hassle-- when iterating on compiler changes, it is annoying to have each tiny change force a library rebuild. To help with this, create a new (unsafe) DISABLE_LIBGO_GOC_DEP cmake control variable that can be enabled by compiler developers to break the dependence on the compiler for all llvm-goc compiled objects. If DISABLE_LIBGO_GOC_DEP, objects depend on a token file that gets created once the first copy of the compiler is built (the token file is not updated when the compiler is rebuilt). Change-Id: I5267c3106abd79db822e0ab2b1ac1387833969a5 Reviewed-on: https://go-review.googlesource.com/112355 Reviewed-by: Cherry Zhang <cherryyz@google.com>
Gollvm is an LLVM-based Go compiler. It incorporates “gofrontend” (a Go language front end written in C++ and shared with GCCGO), a bridge components (which translates from gofrontend IR to LLVM IR), and a driver that sends the resulting IR through the LLVM back end. Gollvm is still at an early stage of development.
Gollvm (name still not finalized) is set up to be a subprojects within the LLVM tools directory, similar to how things work for “clang” or “compiler-rt”: you check out a copy of the LLVM source tree and then within that tree you check out additional git repos.
You'll need to have an up-to-date copy of cmake on your system (3.6 vintage).
// Here 'workarea' will contain a copy of the LLVM source tree and one or more build areas % mkdir workarea % cd workarea // Sources % git clone http://llvm.org/git/llvm.git ... % cd llvm/tools % git clone https://go.googlesource.com/gollvm ... % cd gollvm % git clone https://go.googlesource.com/gofrontend ... % cd libgo % git clone https://github.com/libffi/libffi.git ... % git clone https://github.com/ianlancetaylor/libbacktrace.git ... % // Create a build directory and run cmake % mkdir build.opt % cd build.opt % cmake -DCMAKE_BUILD_TYPE=Debug -DLLVM_USE_LINKER=gold -G Ninja ../llvm // Build ninja <gollvm target(s)>
Within /llvm/tools/gollvm, the following directories are of interest:
.../llvm/tools/gollvm:
.../llvm/tools/gollvm/driver:
.../llvm/tools/gollvm/gofrontend:
.../llvm/tools/gollvm/bridge:
.../llvm/tools/gollvm/unittests:
The executable llvm-goc is the main compiler driver for gollvm; it functions as a compiler (consuming source for a Go package and producing an object file) and will eventually include any necessary invocations of the linker or assembler. This program not fully usable on its own at the moment; using it requries a companion gccgo installation.
// From within <workarea>/build.opt:
% ninja llvm-goc
% cat micro.go
package foo
func Bar() int {
return 1
}
% ./bin/llvm-goc -fgo-pkgpath=foo -O3 -o micro.s micro.go
%
At the moment the CMake build/install support for libgo is not entirely on line, which makes it difficult/unwieldy to use for running actual Go programs. As an interim workaround, I've written a shim/wrapper script that allows you to use llvm-goc in combination with an existing GCCGO installation, using gccgo for the runtime/libraries and the linking step, but llvm-goc for any compilation.
The wrapper script can be found in the tools/ subdir. To use it, build a copy of GCCGO and run “make install” to copy the bits into an install directory. From the GCCGO install directory, you can insert the wrapper by running it with the “--install” option:
% cd /my/gccgo/install % /my/gollvm/sandbox/tools/gollvm-wrap.py --install executing: mv bin/gccgo bin/gccgo.real executing: chmod 0755 bin/gccgo executing: cp /my/gollvm/sandbox/tools/gollvm-wrap.py bin executing: cp /my/gollvm/sandbox/tools/script_utils.py bin wrapper installed successfully %
At this point you can now run “go build”, “go run”, etc using GCCGO -- the compilation steps will be performed by llvm-goc, and the remainder (linking, incorporation of runtime) will be done by gccgo. Example:
% cd $GOPATH/src/himom % go run himom.go hi mom! % go run -compiler gccgo himom.go hi mom! % GOLLVM_WRAP_OPTIONS=-t go run -compiler gccgo himom.go # command-line-arguments + llvm-goc -I $WORK -c -g -m64 -fgo-relative-import-path=_/mygopath/src/himom -o $WORK/command-line-arguments/_obj/_go_.o.s ./himom.go -L /my/gccgo/install/lib64/go/8.0.0/x86_64-pc-linux-gnu hi mom %
Here are instructions on building and running the unit tests for the middle layer:
// From within <workarea>/build.opt: // Build unit test % ninja GoBackendCoreTests // Run unit test % ./tools/gollvm/unittests/BackendCore/GoBackendCoreTests [==========] Running 10 tests from 2 test cases. [----------] Global test environment set-up. [----------] 9 tests from BackendCoreTests [ RUN ] BackendCoreTests.MakeBackend [ OK ] BackendCoreTests.MakeBackend (1 ms) [ RUN ] BackendCoreTests.ScalarTypes [ OK ] BackendCoreTests.ScalarTypes (0 ms) [ RUN ] BackendCoreTests.StructTypes [ OK ] BackendCoreTests.StructTypes (1 ms) [ RUN ] BackendCoreTests.ComplexTypes [ OK ] BackendCoreTests.ComplexTypes (0 ms) [ RUN ] BackendCoreTests.FunctionTypes [ OK ] BackendCoreTests.FunctionTypes (0 ms) [ RUN ] BackendCoreTests.PlaceholderTypes [ OK ] BackendCoreTests.PlaceholderTypes (0 ms) [ RUN ] BackendCoreTests.ArrayTypes [ OK ] BackendCoreTests.ArrayTypes (0 ms) [ RUN ] BackendCoreTests.NamedTypes [ OK ] BackendCoreTests.NamedTypes (0 ms) [ RUN ] BackendCoreTests.TypeUtils ... [ PASSED ] 10 tests.
The unit tests currently work by instantiating an LLVM Backend instance and making backend method calls (to mimic what the frontend would do), then inspects the results to make sure they are as expected. Here is an example:
TEST(BackendCoreTests, ComplexTypes) {
LLVMContext C;
Type *ft = Type::getFloatTy(C);
Type *dt = Type::getDoubleTy(C);
std::unique_ptr<Backend> be(go_get_backend(C));
Btype *c32 = be->complex_type(64);
ASSERT_TRUE(c32 != NULL);
ASSERT_EQ(c32->type(), mkTwoFieldLLvmStruct(C, ft, ft));
Btype *c64 = be->complex_type(128);
ASSERT_TRUE(c64 != NULL);
ASSERT_EQ(c64->type(), mkTwoFieldLLvmStruct(C, dt, dt));
}
The test above makes sure that the LLVM type we get as a result of calling Backend::complex_type() is kosher and matches up to expectations.
To build the Go runtime and standard libraries, use the following:
// From within <workarea>/build.opt: // Build Go runtime and standard libraries % ninja libgo_all
This will compile static (.a) and dynamic (.so) versions of the library.