Support option -plugin-opt=dwo_dir=

[yunlian]

Summary

This adds support to option -plugin-opt=dwo_dir=${DIR}. This option is used to specify the directory to store the .dwo files when LTO and debug fission is used
at the same time.

[yunlian]

ping?

[yunlian]

ping?

[pcc]

Can you add a test case?

ELF/Options.td

452

nit: Directory

[pcc]

Looks like you updated this review with the wrong patch.

[ruiu]

ELF/Options.td

451

sort

[yunlian]

Upload the right patch, fixed the option order in Options.td

[pcc]

ELF/Options.td

437

The new option should appear before this line I think.

447

nit: Directory

[pcc]

Oh and there's still no test.

[yunlian]

I will upload a test later.

[yunlian]

unittest added

[ruiu]

test/ELF/lto/thinlto-debug-fission.ll

4

Remove.

5

Double space characters.

8

If the specified directory doesn't exist, does --plug-opt=dwo_dir creates a new directory?

8

-o /dev/null is preferred if you don't need an output file.

[yunlian]

test/ELF/lto/thinlto-debug-fission.ll

8

Yes, it will create a new directory if the specified directory does not exist.

[yunlian]

ping?

[pcc]

LGTM

test/ELF/lto/thinlto-debug-fission.ll

8

I'd add an rm -rf %T/dwo to test that and make sure that files aren't left over from previous runs.

[yunlian]

removed temporary file generated by the test.

[pcc]

test/ELF/lto/thinlto-debug-fission.ll

8

Move the rm -rf before the call to ld.lld.

[pcc]

test/ELF/lto/thinlto-debug-fission.ll

8

Move the rm -rf before the call to ld.lld.

Looks like this wasn't resolved before committing.

[yunlian]

I added the 'rm' after the test. Will upload another patch to fix that.

ELF/Config.h

 // and such fields have the same name as the corresponding options.
 // Most fields are initialized by the driver.
 struct Configuration {
   uint8_t OSABI = 0;
   llvm::CachePruningPolicy ThinLTOCachePolicy;
   llvm::StringMap<uint64_t> SectionStartMap;
   llvm::StringRef Chroot;
   llvm::StringRef DynamicLinker;
+  llvm::StringRef DwoDir;
   llvm::StringRef Entry;
   llvm::StringRef Emulation;
   llvm::StringRef Fini;
   llvm::StringRef Init;
   llvm::StringRef LTOAAPipeline;
   llvm::StringRef LTONewPmPasses;
   llvm::StringRef LTOObjPath;
   llvm::StringRef LTOSampleProfile;

ELF/Driver.cpp

void LinkerDriver::readConfigs(opt::InputArgList &Args) {
   Config->Chroot = Args.getLastArgValue(OPT_chroot);
   Config->CompressDebugSections = getCompressDebugSections(Args);
   Config->Cref = Args.hasFlag(OPT_cref, OPT_no_cref, false);
   Config->DefineCommon = Args.hasFlag(OPT_define_common, OPT_no_define_common,
                                       !Args.hasArg(OPT_relocatable));
   Config->Demangle = Args.hasFlag(OPT_demangle, OPT_no_demangle, true);
   Config->DisableVerify = Args.hasArg(OPT_disable_verify);
   Config->Discard = getDiscard(Args);
+  Config->DwoDir = Args.getLastArgValue(OPT_plugin_opt_dwo_dir_eq);
   Config->DynamicLinker = getDynamicLinker(Args);
   Config->EhFrameHdr =
       Args.hasFlag(OPT_eh_frame_hdr, OPT_no_eh_frame_hdr, false);
   Config->EmitRelocs = Args.hasArg(OPT_emit_relocs);
   Config->EnableNewDtags =
       Args.hasFlag(OPT_enable_new_dtags, OPT_disable_new_dtags, true);
   Config->Entry = Args.getLastArgValue(OPT_entry);
   Config->ExportDynamic =

ELF/LTO.cpp

static lto::Config createConfig() {
 
   // Set up optimization remarks if we've been asked to.
   C.RemarksFilename = Config->OptRemarksFilename;
   C.RemarksWithHotness = Config->OptRemarksWithHotness;
 
   C.SampleProfile = Config->LTOSampleProfile;
   C.UseNewPM = Config->LTONewPassManager;
   C.DebugPassManager = Config->LTODebugPassManager;
+  C.DwoDir = Config->DwoDir;
 
   if (Config->SaveTemps)
     checkError(C.addSaveTemps(Config->OutputFile.str() + ".",
                               /*UseInputModulePath*/ true));
   return C;
 }
 
 BitcodeCompiler::BitcodeCompiler() {

ELF/Options.td

def thinlto_cache_dir: J<"thinlto-cache-dir=">,
   HelpText<"Path to ThinLTO cached object file directory">;
 defm thinlto_cache_policy: Eq<"thinlto-cache-policy", "Pruning policy for the ThinLTO cache">;
 def thinlto_jobs: J<"thinlto-jobs=">, HelpText<"Number of ThinLTO jobs">;
 
 def: J<"plugin-opt=O">, Alias<lto_O>, HelpText<"Alias for -lto-O">;
 def: F<"plugin-opt=debug-pass-manager">,
   Alias<lto_debug_pass_manager>, HelpText<"Alias for -lto-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: 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=">;
 def: F<"plugin-opt=new-pass-manager">,
   Alias<lto_new_pass_manager>, HelpText<"Alias for -lto-new-pass-manager">;
 def plugin_opt_obj_path_eq: J<"plugin-opt=obj-path=">;
 def: J<"plugin-opt=sample-profile=">,
   Alias<lto_sample_profile>, HelpText<"Alias for -lto-sample-profile">;
 def: F<"plugin-opt=save-temps">, Alias<save_temps>, HelpText<"Alias for -save-temps">;
 def plugin_opt_thinlto_emit_imports_files: F<"plugin-opt=thinlto-emit-imports-files">;
 def plugin_opt_thinlto_index_only: F<"plugin-opt=thinlto-index-only">;
 def plugin_opt_thinlto_index_only_eq: J<"plugin-opt=thinlto-index-only=">;
 def plugin_opt_thinlto_object_suffix_replace_eq: J<"plugin-opt=thinlto-object-suffix-replace=">;
 def plugin_opt_thinlto_prefix_replace_eq: J<"plugin-opt=thinlto-prefix-replace=">;
 
 // Ignore LTO plugin-related options.
 // clang -flto passes -plugin and -plugin-opt to the linker. This is required
 // for ld.gold and ld.bfd to get LTO working. But it's not for lld which doesn't
 // rely on a plugin. Instead of detecting which linker is used on clang side we
 // just ignore the option on lld side as it's easier. In fact, the linker could
 // be called 'ld' and understanding which linker is used would require parsing of
 // --version output.
 defm plugin: Eq<"plugin", "Ignored for compatibility with GNU linkers">;
 

test/ELF/lto/thinlto-debug-fission.ll

+; REQUIRES: x86
+
+; RUN: opt %s -o %t1.o
+
+; Test to ensure that --plugin-opt=dwo_dir=$DIR creates .dwo files under $DIR
+; RUN: ld.lld --plugin-opt=dwo_dir=%T/dwo -shared %t1.o -o /dev/null
+; RUN: llvm-readobj -h %T/dwo/0.dwo | FileCheck %s
+; RUN: rm -rf %T/dwo
+
+; CHECK: Format: ELF64-x86-64
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+declare void @g(...)
+
+define void @f() {
+entry:
+  call void (...) @g()
+  ret void
+}