[lld] r349198 - Add --plugin-opt=emit-llvm option.

[Rui Ueyama via llvm-commits]

Author: ruiu
Date: Fri Dec 14 13:58:49 2018
New Revision: 349198

URL: http://llvm.org/viewvc/llvm-project?rev=349198&view=rev
Log:
Add --plugin-opt=emit-llvm option.

`--plugin-opt=emit-llvm` is an option for LTO. It makes the linker to
combine all bitcode files and write the result to an output file without
doing codegen. Gold LTO plugin has this option.

This option is being used for some post-link code analysis tools that
have to see a whole program but don't need to see them in the native
machine code.

Differential Revision: https://reviews.llvm.org/D55717

Added:
    lld/trunk/test/ELF/lto/emit-llvm.ll
Modified:
    lld/trunk/ELF/Config.h
    lld/trunk/ELF/Driver.cpp
    lld/trunk/ELF/LTO.cpp
    lld/trunk/ELF/Options.td

Modified: lld/trunk/ELF/Config.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Config.h?rev=349198&r1=349197&r2=349198&view=diff
==============================================================================
--- lld/trunk/ELF/Config.h (original)
+++ lld/trunk/ELF/Config.h Fri Dec 14 13:58:49 2018
@@ -135,6 +135,7 @@ struct Configuration {
   bool Demangle = true;
   bool DisableVerify;
   bool EhFrameHdr;
+  bool EmitLLVM;
   bool EmitRelocs;
   bool EnableNewDtags;
   bool ExecuteOnly;

Modified: lld/trunk/ELF/Driver.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Driver.cpp?rev=349198&r1=349197&r2=349198&view=diff
==============================================================================
--- lld/trunk/ELF/Driver.cpp (original)
+++ lld/trunk/ELF/Driver.cpp Fri Dec 14 13:58:49 2018
@@ -776,6 +776,7 @@ void LinkerDriver::readConfigs(opt::Inpu
   Config->DynamicLinker = getDynamicLinker(Args);
   Config->EhFrameHdr =
       Args.hasFlag(OPT_eh_frame_hdr, OPT_no_eh_frame_hdr, false);
+  Config->EmitLLVM = Args.hasArg(OPT_plugin_opt_emit_llvm, false);
   Config->EmitRelocs = Args.hasArg(OPT_emit_relocs);
   Config->CallGraphProfileSort = Args.hasFlag(
       OPT_call_graph_profile_sort, OPT_no_call_graph_profile_sort, true);
@@ -1581,6 +1582,12 @@ template <class ELFT> void LinkerDriver:
   if (Config->ThinLTOIndexOnly)
     return;
 
+  // Likewise, --plugin-opt=emit-llvm is an option to make LTO create
+  // an output file in bitcode and exit, so that you can just get a
+  // combined bitcode file.
+  if (Config->EmitLLVM)
+    return;
+
   // Apply symbol renames for -wrap.
   if (!Wrapped.empty())
     wrapSymbols<ELFT>(Wrapped);

Modified: lld/trunk/ELF/LTO.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/LTO.cpp?rev=349198&r1=349197&r2=349198&view=diff
==============================================================================
--- lld/trunk/ELF/LTO.cpp (original)
+++ lld/trunk/ELF/LTO.cpp Fri Dec 14 13:58:49 2018
@@ -103,6 +103,14 @@ static lto::Config createConfig() {
   C.DebugPassManager = Config->LTODebugPassManager;
   C.DwoDir = Config->DwoDir;
 
+  if (Config->EmitLLVM) {
+    C.PostInternalizeModuleHook = [](size_t Task, const Module &M) {
+      if (std::unique_ptr<raw_fd_ostream> OS = openFile(Config->OutputFile))
+        WriteBitcodeToFile(M, *OS, false);
+      return false;
+    };
+  }
+
   if (Config->SaveTemps)
     checkError(C.addSaveTemps(Config->OutputFile.str() + ".",
                               /*UseInputModulePath*/ true));

Modified: lld/trunk/ELF/Options.td
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Options.td?rev=349198&r1=349197&r2=349198&view=diff
==============================================================================
--- lld/trunk/ELF/Options.td (original)
+++ lld/trunk/ELF/Options.td Fri Dec 14 13:58:49 2018
@@ -458,6 +458,7 @@ def: F<"plugin-opt=debug-pass-manager">,
 def: F<"plugin-opt=disable-verify">, Alias<disable_verify>, HelpText<"Alias for -disable-verify">;
 def plugin_opt_dwo_dir_eq: J<"plugin-opt=dwo_dir=">,
   HelpText<"Directory to store .dwo files when LTO and debug fission are used">;
+def plugin_opt_emit_llvm: F<"plugin-opt=emit-llvm">;
 def: J<"plugin-opt=jobs=">, Alias<thinlto_jobs>, HelpText<"Alias for -thinlto-jobs">;
 def: J<"plugin-opt=lto-partitions=">, Alias<lto_partitions>, HelpText<"Alias for -lto-partitions">;
 def plugin_opt_mcpu_eq: J<"plugin-opt=mcpu=">;

Added: lld/trunk/test/ELF/lto/emit-llvm.ll
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/lto/emit-llvm.ll?rev=349198&view=auto
==============================================================================
--- lld/trunk/test/ELF/lto/emit-llvm.ll (added)
+++ lld/trunk/test/ELF/lto/emit-llvm.ll Fri Dec 14 13:58:49 2018
@@ -0,0 +1,14 @@
+; REQUIRES: x86
+
+; RUN: opt -module-hash -module-summary %s -o %t.o
+; RUN: ld.lld --plugin-opt=emit-llvm -o %t.out.o %t.o
+; RUN: llvm-dis < %t.out.o -o - | FileCheck %s
+
+; CHECK: define internal void @main()
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define void @main() {
+  ret void
+}