[PATCH] D18006: [lto] Add beginning of -save-temps option.

[Sean Silva via llvm-commits]

silvas created this revision.
silvas added reviewers: rafael, ruiu.
silvas added subscribers: llvm-commits, Bigcheese.
Herald added a subscriber: joker.eph.

This is useful for debugging issues with LTO.
The option follows the analogous option in ld64 and the gold plugin (per
Rafael's suggestion).

For starters, this only dumps the combined bitcode file.
In a future patch I will add dumping for the .o file.

The naming of the output follows ld64's convention which is slightly more
consistent IMO (consistent `.lto.<extension>` for all the files).

http://reviews.llvm.org/D18006

Files:
  ELF/Config.h
  ELF/Driver.cpp
  ELF/Options.td
  ELF/SymbolTable.cpp
  test/ELF/lto/Inputs/save-temps.ll
  test/ELF/lto/save-temps.ll

Index: test/ELF/lto/save-temps.ll
===================================================================
--- /dev/null
+++ test/ELF/lto/save-temps.ll
@@ -0,0 +1,17 @@
+; REQUIRES: x86
+; RUN: rm -f %t.so %t.so.lto.bc
+; RUN: llvm-as %s -o %t.o
+; RUN: llvm-as %p/Inputs/save-temps.ll -o %t2.o
+; RUN: ld.lld -shared -m elf_x86_64 %t.o %t2.o -o %t.so -save-temps
+; RUN: llvm-nm %t.so | FileCheck %s
+; RUN: llvm-nm %t.so.lto.bc | FileCheck %s
+
+target triple = "x86_64-unknown-linux-gnu"
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+
+define void @foo() {
+  ret void
+}
+
+; CHECK-DAG: T bar
+; CHECK-DAG: T foo
Index: test/ELF/lto/Inputs/save-temps.ll
===================================================================
--- /dev/null
+++ test/ELF/lto/Inputs/save-temps.ll
@@ -0,0 +1,6 @@
+target triple = "x86_64-unknown-linux-gnu"
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+
+define void @bar() {
+  ret void
+}
Index: ELF/SymbolTable.cpp
===================================================================
--- ELF/SymbolTable.cpp
+++ ELF/SymbolTable.cpp
@@ -147,6 +147,13 @@
   Mover.move(std::move(M), Keep, [](GlobalValue &, IRMover::ValueAdder) {});
 }
 
+static void saveBCFile(std::string Path, Module &M) {
+  std::error_code EC;
+  raw_fd_ostream OS(Path, EC, sys::fs::OpenFlags::F_None);
+  check(EC);
+  WriteBitcodeToFile(&M, OS, /* ShouldPreserveUseListOrder */ true);
+}
+
 // Merge all the bitcode files we have seen, codegen the result and return
 // the resulting ObjectFile.
 template <class ELFT>
@@ -156,6 +163,8 @@
   IRMover Mover(Combined);
   for (const std::unique_ptr<BitcodeFile> &F : BitcodeFiles)
     addBitcodeFile(Mover, *F, Context);
+  if (Config->SaveTemps)
+    saveBCFile(Config->OutputFile.str() + ".lto.bc", Combined);
   std::unique_ptr<InputFile> F = codegen(Combined);
   ObjectFiles.emplace_back(cast<ObjectFile<ELFT>>(F.release()));
   return &*ObjectFiles.back();
Index: ELF/Options.td
===================================================================
--- ELF/Options.td
+++ ELF/Options.td
@@ -182,3 +182,6 @@
 
 // Aliases for ignored options
 def alias_version_script_version_script : Joined<["--"], "version-script=">, Alias<version_script>;
+
+// Debugging options
+def save_temps : Flag<["-"], "save-temps">;
Index: ELF/Driver.cpp
===================================================================
--- ELF/Driver.cpp
+++ ELF/Driver.cpp
@@ -239,6 +239,7 @@
   Config->NoinhibitExec = Args.hasArg(OPT_noinhibit_exec);
   Config->PrintGcSections = Args.hasArg(OPT_print_gc_sections);
   Config->Relocatable = Args.hasArg(OPT_relocatable);
+  Config->SaveTemps = Args.hasArg(OPT_save_temps);
   Config->Shared = Args.hasArg(OPT_shared);
   Config->StripAll = Args.hasArg(OPT_strip_all);
   Config->Verbose = Args.hasArg(OPT_verbose);
Index: ELF/Config.h
===================================================================
--- ELF/Config.h
+++ ELF/Config.h
@@ -69,6 +69,7 @@
   bool NoinhibitExec;
   bool PrintGcSections;
   bool Relocatable;
+  bool SaveTemps;
   bool Shared;
   bool Static = false;
   bool StripAll;


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