From aa91871539ca518e81af58485df895f8db30496a Mon Sep 17 00:00:00 2001 From: Augie Fackler Date: Fri, 19 Jan 2024 14:42:43 -0500 Subject: rustc_codegen_llvm: add support for writing summary bitcode Typical uses of ThinLTO don't have any use for this as a standalone file, but distributed ThinLTO uses this to make the linker phase more efficient. With clang you'd do something like `clang -flto=thin -fthin-link-bitcode=foo.indexing.o -c foo.c` and then get both foo.o (full of bitcode) and foo.indexing.o (just the summary or index part of the bitcode). That's then usable by a two-stage linking process that's more friendly to distributed build systems like bazel, which is why I'm working on this area. I talked some to @teresajohnson about naming in this area, as things seem to be a little confused between various blog posts and build systems. "bitcode index" and "bitcode summary" tend to be a little too ambiguous, and she tends to use "thin link bitcode" and "minimized bitcode" (which matches the descriptions in LLVM). Since the clang option is thin-link-bitcode, I went with that to try and not add a new spelling in the world. Per @dtolnay, you can work around the lack of this by using `lld --thinlto-index-only` to do the indexing on regular .o files of bitcode, but that is a bit wasteful on actions when we already have all the information in rustc and could just write out the matching minimized bitcode. I didn't test that at all in our infrastructure, because by the time I learned that I already had this patch largely written. --- compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) (limited to 'compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp') diff --git a/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp b/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp index 067374c0261..c210d2531e7 100644 --- a/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp +++ b/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp @@ -1488,6 +1488,7 @@ LLVMRustPrepareThinLTOImport(const LLVMRustThinLTOData *Data, LLVMModuleRef M, // a ThinLTO summary attached. struct LLVMRustThinLTOBuffer { std::string data; + std::string thin_link_data; }; extern "C" LLVMRustThinLTOBuffer* @@ -1495,6 +1496,7 @@ LLVMRustThinLTOBufferCreate(LLVMModuleRef M, bool is_thin) { auto Ret = std::make_unique(); { auto OS = raw_string_ostream(Ret->data); + auto ThinLinkOS = raw_string_ostream(Ret->thin_link_data); { if (is_thin) { PassBuilder PB; @@ -1508,7 +1510,7 @@ LLVMRustThinLTOBufferCreate(LLVMModuleRef M, bool is_thin) { PB.registerLoopAnalyses(LAM); PB.crossRegisterProxies(LAM, FAM, CGAM, MAM); ModulePassManager MPM; - MPM.addPass(ThinLTOBitcodeWriterPass(OS, nullptr)); + MPM.addPass(ThinLTOBitcodeWriterPass(OS, &ThinLinkOS)); MPM.run(*unwrap(M), MAM); } else { WriteBitcodeToFile(*unwrap(M), OS); @@ -1533,6 +1535,16 @@ LLVMRustThinLTOBufferLen(const LLVMRustThinLTOBuffer *Buffer) { return Buffer->data.length(); } +extern "C" const void* +LLVMRustThinLTOBufferThinLinkDataPtr(const LLVMRustThinLTOBuffer *Buffer) { + return Buffer->thin_link_data.data(); +} + +extern "C" size_t +LLVMRustThinLTOBufferThinLinkDataLen(const LLVMRustThinLTOBuffer *Buffer) { + return Buffer->thin_link_data.length(); +} + // This is what we used to parse upstream bitcode for actual ThinLTO // processing. We'll call this once per module optimized through ThinLTO, and // it'll be called concurrently on many threads. -- cgit 1.4.1-3-g733a5 From de8200c5a441079cfaadd383a8b6897155bfa2c6 Mon Sep 17 00:00:00 2001 From: Augie Fackler Date: Thu, 23 May 2024 14:58:30 -0400 Subject: thinlto: only build summary file if needed If we don't do this, some versions of LLVM (at least 17, experimentally) will double-emit some error messages, which is how I noticed this. Given that it seems to be costing some extra work, let's only request the summary bitcode production if we'll actually bother writing it down, otherwise skip it. --- compiler/rustc_codegen_llvm/src/back/lto.rs | 8 ++++---- compiler/rustc_codegen_llvm/src/back/write.rs | 6 +++--- compiler/rustc_codegen_llvm/src/lib.rs | 4 ++-- compiler/rustc_codegen_llvm/src/llvm/ffi.rs | 2 +- compiler/rustc_codegen_ssa/src/back/write.rs | 2 +- compiler/rustc_codegen_ssa/src/traits/write.rs | 2 +- compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp | 7 +++++-- 7 files changed, 17 insertions(+), 14 deletions(-) (limited to 'compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp') diff --git a/compiler/rustc_codegen_llvm/src/back/lto.rs b/compiler/rustc_codegen_llvm/src/back/lto.rs index 740939eb6bb..0dc91524f84 100644 --- a/compiler/rustc_codegen_llvm/src/back/lto.rs +++ b/compiler/rustc_codegen_llvm/src/back/lto.rs @@ -229,9 +229,9 @@ pub(crate) fn run_thin( thin_lto(cgcx, &dcx, modules, upstream_modules, cached_modules, &symbols_below_threshold) } -pub(crate) fn prepare_thin(module: ModuleCodegen) -> (String, ThinBuffer) { +pub(crate) fn prepare_thin(module: ModuleCodegen, emit_summary: bool) -> (String, ThinBuffer) { let name = module.name; - let buffer = ThinBuffer::new(module.module_llvm.llmod(), true); + let buffer = ThinBuffer::new(module.module_llvm.llmod(), true, emit_summary); (name, buffer) } @@ -671,9 +671,9 @@ unsafe impl Send for ThinBuffer {} unsafe impl Sync for ThinBuffer {} impl ThinBuffer { - pub fn new(m: &llvm::Module, is_thin: bool) -> ThinBuffer { + pub fn new(m: &llvm::Module, is_thin: bool, emit_summary: bool) -> ThinBuffer { unsafe { - let buffer = llvm::LLVMRustThinLTOBufferCreate(m, is_thin); + let buffer = llvm::LLVMRustThinLTOBufferCreate(m, is_thin, emit_summary); ThinBuffer(buffer) } } diff --git a/compiler/rustc_codegen_llvm/src/back/write.rs b/compiler/rustc_codegen_llvm/src/back/write.rs index 4a24bba2bb7..a0fb110d029 100644 --- a/compiler/rustc_codegen_llvm/src/back/write.rs +++ b/compiler/rustc_codegen_llvm/src/back/write.rs @@ -716,9 +716,8 @@ pub(crate) unsafe fn codegen( let _timer = cgcx .prof .generic_activity_with_arg("LLVM_module_codegen_make_bitcode", &*module.name); - let thin = ThinBuffer::new(llmod, config.emit_thin_lto); + let thin = ThinBuffer::new(llmod, config.emit_thin_lto, config.emit_thin_lto_index); let data = thin.data(); - let index_data = thin.thin_link_data(); if let Some(bitcode_filename) = bc_out.file_name() { cgcx.prof.artifact_size( @@ -728,7 +727,8 @@ pub(crate) unsafe fn codegen( ); } - if let Some(thin_link_bitcode_filename) = bc_index_out.file_name() { + if config.emit_thin_lto_index && let Some(thin_link_bitcode_filename) = bc_index_out.file_name() { + let index_data = thin.thin_link_data(); cgcx.prof.artifact_size( "llvm_bitcode_summary", thin_link_bitcode_filename.to_string_lossy(), diff --git a/compiler/rustc_codegen_llvm/src/lib.rs b/compiler/rustc_codegen_llvm/src/lib.rs index 1cecf682e5d..4a9502fa897 100644 --- a/compiler/rustc_codegen_llvm/src/lib.rs +++ b/compiler/rustc_codegen_llvm/src/lib.rs @@ -240,8 +240,8 @@ impl WriteBackendMethods for LlvmCodegenBackend { ) -> Result { back::write::codegen(cgcx, dcx, module, config) } - fn prepare_thin(module: ModuleCodegen) -> (String, Self::ThinBuffer) { - back::lto::prepare_thin(module) + fn prepare_thin(module: ModuleCodegen, emit_summary: bool) -> (String, Self::ThinBuffer) { + back::lto::prepare_thin(module, emit_summary) } fn serialize_module(module: ModuleCodegen) -> (String, Self::ModuleBuffer) { (module.name, back::lto::ModuleBuffer::new(module.module_llvm.llmod())) diff --git a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs index 648e7f12890..1e84c2be3c6 100644 --- a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs +++ b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs @@ -2350,7 +2350,7 @@ extern "C" { #[allow(improper_ctypes)] pub fn LLVMRustModuleInstructionStats(M: &Module, Str: &RustString); - pub fn LLVMRustThinLTOBufferCreate(M: &Module, is_thin: bool) -> &'static mut ThinLTOBuffer; + pub fn LLVMRustThinLTOBufferCreate(M: &Module, is_thin: bool, emit_summary: bool) -> &'static mut ThinLTOBuffer; pub fn LLVMRustThinLTOBufferFree(M: &'static mut ThinLTOBuffer); pub fn LLVMRustThinLTOBufferPtr(M: &ThinLTOBuffer) -> *const c_char; pub fn LLVMRustThinLTOBufferLen(M: &ThinLTOBuffer) -> size_t; diff --git a/compiler/rustc_codegen_ssa/src/back/write.rs b/compiler/rustc_codegen_ssa/src/back/write.rs index cee177d5eec..0432659d371 100644 --- a/compiler/rustc_codegen_ssa/src/back/write.rs +++ b/compiler/rustc_codegen_ssa/src/back/write.rs @@ -891,7 +891,7 @@ fn execute_optimize_work_item( match lto_type { ComputedLtoType::No => finish_intra_module_work(cgcx, module, module_config), ComputedLtoType::Thin => { - let (name, thin_buffer) = B::prepare_thin(module); + let (name, thin_buffer) = B::prepare_thin(module, false); if let Some(path) = bitcode { fs::write(&path, thin_buffer.data()).unwrap_or_else(|e| { panic!("Error writing pre-lto-bitcode file `{}`: {}", path.display(), e); diff --git a/compiler/rustc_codegen_ssa/src/traits/write.rs b/compiler/rustc_codegen_ssa/src/traits/write.rs index b4b23812d4d..21efca53a47 100644 --- a/compiler/rustc_codegen_ssa/src/traits/write.rs +++ b/compiler/rustc_codegen_ssa/src/traits/write.rs @@ -56,7 +56,7 @@ pub trait WriteBackendMethods: 'static + Sized + Clone { module: ModuleCodegen, config: &ModuleConfig, ) -> Result; - fn prepare_thin(module: ModuleCodegen) -> (String, Self::ThinBuffer); + fn prepare_thin(module: ModuleCodegen, want_summary: bool) -> (String, Self::ThinBuffer); fn serialize_module(module: ModuleCodegen) -> (String, Self::ModuleBuffer); } diff --git a/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp b/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp index c210d2531e7..3fcf3aca8af 100644 --- a/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp +++ b/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp @@ -1492,7 +1492,7 @@ struct LLVMRustThinLTOBuffer { }; extern "C" LLVMRustThinLTOBuffer* -LLVMRustThinLTOBufferCreate(LLVMModuleRef M, bool is_thin) { +LLVMRustThinLTOBufferCreate(LLVMModuleRef M, bool is_thin, bool emit_summary) { auto Ret = std::make_unique(); { auto OS = raw_string_ostream(Ret->data); @@ -1510,7 +1510,10 @@ LLVMRustThinLTOBufferCreate(LLVMModuleRef M, bool is_thin) { PB.registerLoopAnalyses(LAM); PB.crossRegisterProxies(LAM, FAM, CGAM, MAM); ModulePassManager MPM; - MPM.addPass(ThinLTOBitcodeWriterPass(OS, &ThinLinkOS)); + // We only pass ThinLinkOS to be filled in if we want the summary, + // because otherwise LLVM does extra work and may double-emit some + // errors or warnings. + MPM.addPass(ThinLTOBitcodeWriterPass(OS, emit_summary ? &ThinLinkOS : nullptr)); MPM.run(*unwrap(M), MAM); } else { WriteBitcodeToFile(*unwrap(M), OS); -- cgit 1.4.1-3-g733a5 From b37a448616a370ba02eeaa7d7c8289fa85d35fc9 Mon Sep 17 00:00:00 2001 From: Scott Mabin Date: Sat, 12 Sep 2020 23:20:14 +0100 Subject: Teach rustc about the Xtensa arch. --- compiler/rustc_llvm/build.rs | 1 + compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp | 7 +++++++ 2 files changed, 8 insertions(+) (limited to 'compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp') diff --git a/compiler/rustc_llvm/build.rs b/compiler/rustc_llvm/build.rs index 024f6f89a4b..cdaabb036c2 100644 --- a/compiler/rustc_llvm/build.rs +++ b/compiler/rustc_llvm/build.rs @@ -23,6 +23,7 @@ const OPTIONAL_COMPONENTS: &[&str] = &[ "nvptx", "hexagon", "riscv", + "xtensa", "bpf", ]; diff --git a/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp b/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp index 3fcf3aca8af..a027ddcc150 100644 --- a/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp +++ b/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp @@ -155,6 +155,12 @@ extern "C" void LLVMRustTimeTraceProfilerFinish(const char* FileName) { #define SUBTARGET_SPARC #endif +#ifdef LLVM_COMPONENT_XTENSA +#define SUBTARGET_XTENSA SUBTARGET(XTENSA) +#else +#define SUBTARGET_XTENSA +#endif + #ifdef LLVM_COMPONENT_HEXAGON #define SUBTARGET_HEXAGON SUBTARGET(Hexagon) #else @@ -180,6 +186,7 @@ extern "C" void LLVMRustTimeTraceProfilerFinish(const char* FileName) { SUBTARGET_MSP430 \ SUBTARGET_SPARC \ SUBTARGET_HEXAGON \ + SUBTARGET_XTENSA \ SUBTARGET_RISCV \ SUBTARGET_LOONGARCH \ -- cgit 1.4.1-3-g733a5