From 61fc10d6a520f267e11009ce8fce88d73615796b Mon Sep 17 00:00:00 2001 From: Mircea Trofin Date: Mon, 14 Sep 2020 10:45:00 -0700 Subject: [PATCH] [ThinLTO] add post-thinlto-merge option to -lto-embed-bitcode This will embed bitcode after (Thin)LTO merge, but before optimizations. In the case the thinlto backend is called from clang, the .llvmcmd section is also produced. Doing so in the case where the caller is the linker doesn't yet have a motivation, and would require plumbing through command line args. Differential Revision: https://reviews.llvm.org/D87636 --- clang/lib/CodeGen/BackendUtil.cpp | 7 +++--- clang/test/CodeGen/Inputs/start-lib1.ll | 9 ++++++++ clang/test/CodeGen/Inputs/start-lib2.ll | 6 +++++ clang/test/CodeGen/thinlto_embed_bitcode.ll | 30 +++++++++++++++++++++++++ llvm/include/llvm/LTO/LTOBackend.h | 3 ++- llvm/lib/LTO/LTOBackend.cpp | 34 +++++++++++++++++++++++++---- llvm/test/LTO/X86/Inputs/start-lib1.ll | 1 + llvm/test/LTO/X86/embed-bitcode.ll | 9 +++++++- 8 files changed, 90 insertions(+), 9 deletions(-) create mode 100644 clang/test/CodeGen/Inputs/start-lib1.ll create mode 100644 clang/test/CodeGen/Inputs/start-lib2.ll create mode 100644 clang/test/CodeGen/thinlto_embed_bitcode.ll diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp index 5fc80d4..01f7e23 100644 --- a/clang/lib/CodeGen/BackendUtil.cpp +++ b/clang/lib/CodeGen/BackendUtil.cpp @@ -1647,9 +1647,10 @@ static void runThinLTOBackend( Conf.CGFileType = getCodeGenFileType(Action); break; } - if (Error E = thinBackend( - Conf, -1, AddStream, *M, *CombinedIndex, ImportList, - ModuleToDefinedGVSummaries[M->getModuleIdentifier()], ModuleMap)) { + if (Error E = + thinBackend(Conf, -1, AddStream, *M, *CombinedIndex, ImportList, + ModuleToDefinedGVSummaries[M->getModuleIdentifier()], + ModuleMap, &CGOpts.CmdArgs)) { handleAllErrors(std::move(E), [&](ErrorInfoBase &EIB) { errs() << "Error running ThinLTO backend: " << EIB.message() << '\n'; }); diff --git a/clang/test/CodeGen/Inputs/start-lib1.ll b/clang/test/CodeGen/Inputs/start-lib1.ll new file mode 100644 index 0000000..18b6ea2 --- /dev/null +++ b/clang/test/CodeGen/Inputs/start-lib1.ll @@ -0,0 +1,9 @@ +target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128" +target triple = "x86_64-unknown-linux-gnu" + +declare void @bar() + +define void @foo() { + call void @bar() + ret void +} diff --git a/clang/test/CodeGen/Inputs/start-lib2.ll b/clang/test/CodeGen/Inputs/start-lib2.ll new file mode 100644 index 0000000..68b3c83 --- /dev/null +++ b/clang/test/CodeGen/Inputs/start-lib2.ll @@ -0,0 +1,6 @@ +target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128" +target triple = "x86_64-unknown-linux-gnu" + +define void @bar() { + ret void +} diff --git a/clang/test/CodeGen/thinlto_embed_bitcode.ll b/clang/test/CodeGen/thinlto_embed_bitcode.ll new file mode 100644 index 0000000..4efb525 --- /dev/null +++ b/clang/test/CodeGen/thinlto_embed_bitcode.ll @@ -0,0 +1,30 @@ +; REQUIRES: x86-registered-target + +; check the -lto-embed-bitcode=post-thinlto-merge does not perform optimizations +; we expect 't1' - i.e start-lib1.ll's products - have both foo and bar defined, +; but the bar call is still made from foo. +; RUN: opt -module-summary %p/Inputs/start-lib1.ll -o %t1.bc +; RUN: opt -module-summary %p/Inputs/start-lib2.ll -o %t2.bc +; RUN: llvm-lto -thinlto -o %t.o %t1.bc %t2.bc + +; RUN: %clang -target x86_64-unknown-linux-gnu -O2 -o %t.o -x ir %t1.bc -c -fthinlto-index=%t.o.thinlto.bc -mllvm -lto-embed-bitcode=post-merge-pre-opt +; RUN: llvm-readelf -S %t.o | FileCheck %s --check-prefixes=CHECK-ELF,CHECK-CMD +; RUN: llvm-objcopy --dump-section=.llvmbc=%t-embedded.bc %t.o /dev/null +; RUN: llvm-dis %t-embedded.bc -o - | FileCheck %s --check-prefixes=CHECK,CHECK-NOOPT + +; For the optimized case, we expect the inlining of foo into bar to happen. +; RUN: %clang -target x86_64-unknown-linux-gnu -O2 -o %t.o -x ir %t1.bc -c -fthinlto-index=%t.o.thinlto.bc -mllvm -lto-embed-bitcode=optimized +; RUN: llvm-readelf -S %t.o | FileCheck %s --check-prefixes=CHECK-ELF,CHECK-NO-CMD +; RUN: llvm-objcopy --dump-section=.llvmbc=%t-embedded.bc %t.o /dev/null +; RUN: llvm-dis %t-embedded.bc -o - | FileCheck %s --check-prefixes=CHECK,CHECK-OPT + +; CHECK-ELF: .text PROGBITS 0000000000000000 [[#%x,OFF:]] [[#%x,SIZE:]] 00 AX 0 +; CHECK-ELF-NEXT: .llvmbc PROGBITS 0000000000000000 [[#%x,OFF:]] [[#%x,SIZE:]] 00 0 +; CHECK-ELF-CMD: .llvmcmd +; CHECK-ELF-NO-CMD-NOT: .llvmcmd + +; CHECK: define void @foo() +; CHECK-OPT-NEXT: ret void +; CHECK-NOOPT-NEXT: call void @bar() +; CHECK-NOOPT: define available_externally void @bar() !thinlto_src_module !0 { +; CHECK-NOOPT-NEXT: ret void diff --git a/llvm/include/llvm/LTO/LTOBackend.h b/llvm/include/llvm/LTO/LTOBackend.h index 0226e4a..735969c 100644 --- a/llvm/include/llvm/LTO/LTOBackend.h +++ b/llvm/include/llvm/LTO/LTOBackend.h @@ -44,7 +44,8 @@ Error thinBackend(const Config &C, unsigned Task, AddStreamFn AddStream, Module &M, const ModuleSummaryIndex &CombinedIndex, const FunctionImporter::ImportMapTy &ImportList, const GVSummaryMapTy &DefinedGlobals, - MapVector &ModuleMap); + MapVector &ModuleMap, + const std::vector *CmdArgs = nullptr); Error finalizeOptimizationRemarks( std::unique_ptr DiagOutputFile); diff --git a/llvm/lib/LTO/LTOBackend.cpp b/llvm/lib/LTO/LTOBackend.cpp index 00309b6..4c5778e8 100644 --- a/llvm/lib/LTO/LTOBackend.cpp +++ b/llvm/lib/LTO/LTOBackend.cpp @@ -50,9 +50,12 @@ using namespace llvm; using namespace lto; +#define DEBUG_TYPE "lto-backend" + enum class LTOBitcodeEmbedding { DoNotEmbed = 0, EmbedOptimized = 1, + EmbedPostMergePreOptimized = 2 }; static cl::opt EmbedBitcode( @@ -60,7 +63,10 @@ static cl::opt EmbedBitcode( cl::values(clEnumValN(LTOBitcodeEmbedding::DoNotEmbed, "none", "Do not embed"), clEnumValN(LTOBitcodeEmbedding::EmbedOptimized, "optimized", - "Embed after all optimization passes")), + "Embed after all optimization passes"), + clEnumValN(LTOBitcodeEmbedding::EmbedPostMergePreOptimized, + "post-merge-pre-opt", + "Embed post merge, but before optimizations")), cl::desc("Embed LLVM bitcode in object files produced by LTO")); LLVM_ATTRIBUTE_NORETURN static void reportOpenError(StringRef Path, Twine Msg) { @@ -346,7 +352,25 @@ static void runOldPMPasses(const Config &Conf, Module &Mod, TargetMachine *TM, bool opt(const Config &Conf, TargetMachine *TM, unsigned Task, Module &Mod, bool IsThinLTO, ModuleSummaryIndex *ExportSummary, - const ModuleSummaryIndex *ImportSummary) { + const ModuleSummaryIndex *ImportSummary, + const std::vector *CmdArgs = nullptr) { + if (EmbedBitcode == LTOBitcodeEmbedding::EmbedPostMergePreOptimized) { + // FIXME: the motivation for capturing post-merge bitcode and command line + // is replicating the compilation environment from bitcode, without needing + // to understand the dependencies (the functions to be imported). This + // assumes a clang - based invocation, case in which we have the command + // line. + // It's not very clear how the above motivation would map in the + // linker-based case, so we currently don't plumb the command line args in + // that case. + if (CmdArgs == nullptr) + LLVM_DEBUG( + dbgs() << "Post-(Thin)LTO merge bitcode embedding was requested, but " + "command line arguments are not available"); + llvm::EmbedBitcodeInModule(Mod, llvm::MemoryBufferRef(), + /*EmbedBitcode*/ true, + /*EmbedMarker*/ false, CmdArgs); + } // FIXME: Plumb the combined index into the new pass manager. if (!Conf.OptPipeline.empty()) runNewPMCustomPasses(Conf, Mod, TM, Conf.OptPipeline, Conf.AAPipeline, @@ -531,7 +555,8 @@ Error lto::thinBackend(const Config &Conf, unsigned Task, AddStreamFn AddStream, Module &Mod, const ModuleSummaryIndex &CombinedIndex, const FunctionImporter::ImportMapTy &ImportList, const GVSummaryMapTy &DefinedGlobals, - MapVector &ModuleMap) { + MapVector &ModuleMap, + const std::vector *CmdArgs) { Expected TOrErr = initAndLookupTarget(Conf, Mod); if (!TOrErr) return TOrErr.takeError(); @@ -599,7 +624,8 @@ Error lto::thinBackend(const Config &Conf, unsigned Task, AddStreamFn AddStream, return finalizeOptimizationRemarks(std::move(DiagnosticOutputFile)); if (!opt(Conf, TM.get(), Task, Mod, /*IsThinLTO=*/true, - /*ExportSummary=*/nullptr, /*ImportSummary=*/&CombinedIndex)) + /*ExportSummary=*/nullptr, /*ImportSummary=*/&CombinedIndex, + CmdArgs)) return finalizeOptimizationRemarks(std::move(DiagnosticOutputFile)); codegen(Conf, TM.get(), AddStream, Task, Mod, CombinedIndex); diff --git a/llvm/test/LTO/X86/Inputs/start-lib1.ll b/llvm/test/LTO/X86/Inputs/start-lib1.ll index 9f42e6a..18b6ea2 100644 --- a/llvm/test/LTO/X86/Inputs/start-lib1.ll +++ b/llvm/test/LTO/X86/Inputs/start-lib1.ll @@ -4,5 +4,6 @@ target triple = "x86_64-unknown-linux-gnu" declare void @bar() define void @foo() { + call void @bar() ret void } diff --git a/llvm/test/LTO/X86/embed-bitcode.ll b/llvm/test/LTO/X86/embed-bitcode.ll index c8b4d0f..bdddd07 100644 --- a/llvm/test/LTO/X86/embed-bitcode.ll +++ b/llvm/test/LTO/X86/embed-bitcode.ll @@ -11,13 +11,20 @@ ; RUN: llvm-lto2 run -r %t1.o,_start,px -r %t2.o,foo,px -r %t3.o,bar,px -r %t2.o,bar,lx -lto-embed-bitcode=optimized -o %t3 %t1.o %t2.o %t3.o ; RUN: llvm-readelf -S %t3.0 | FileCheck %s --check-prefix=CHECK-ELF ; RUN: llvm-objcopy --dump-section=.llvmbc=%t-embedded.bc %t3.0 /dev/null -; RUN: llvm-dis %t-embedded.bc -o - | FileCheck %s --check-prefix=CHECK-LL +; RUN: llvm-dis %t-embedded.bc -o - | FileCheck %s --check-prefixes=CHECK-LL,CHECK-OPT + +; RUN: llvm-lto2 run -r %t1.o,_start,px -r %t2.o,foo,px -r %t3.o,bar,px -r %t2.o,bar,lx -lto-embed-bitcode=post-merge-pre-opt -o %t3 %t1.o %t2.o %t3.o +; RUN: llvm-readelf -S %t3.0 | FileCheck %s --check-prefix=CHECK-ELF +; RUN: llvm-objcopy --dump-section=.llvmbc=%t-embedded.bc %t3.0 /dev/null +; RUN: llvm-dis %t-embedded.bc -o - | FileCheck %s --check-prefixes=CHECK-LL,CHECK-NOOPT ; CHECK-ELF: .text PROGBITS 0000000000000000 [[#%x,OFF:]] [[#%x,SIZE:]] 00 AX 0 ; CHECK-ELF-NEXT: .llvmbc PROGBITS 0000000000000000 [[#%x,OFF:]] [[#%x,SIZE:]] 00 0 ; CHECK-LL: @_start ; CHECK-LL: @foo +; CHECK-OPT-NEXT: ret void +; CHECK-NOOPT-NEXT: call void @bar ; CHECK-LL: @bar target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128" -- 2.7.4