r298639 - [ThinLTO] Clang support for emitting minimized bitcode for thin link

[Teresa Johnson via cfe-commits]

Author: tejohnson
Date: Thu Mar 23 14:47:49 2017
New Revision: 298639

URL: http://llvm.org/viewvc/llvm-project?rev=298639&view=rev
Log:
[ThinLTO] Clang support for emitting minimized bitcode for thin link

Summary:
Clang companion patch to LLVM patch D31027, which adds support
for emitting minimized bitcode file for use in the thin link step.
Add a cc1 option -fthin-link-bitcode=<file> to trigger this behavior.

Depends on D31027.

Reviewers: mehdi_amini, pcc

Subscribers: cfe-commits, Prazek

Differential Revision: https://reviews.llvm.org/D31050

Added:
    cfe/trunk/test/CodeGen/thin_link_bitcode.c
Modified:
    cfe/trunk/include/clang/Driver/CC1Options.td
    cfe/trunk/include/clang/Frontend/CodeGenOptions.h
    cfe/trunk/lib/CodeGen/BackendUtil.cpp
    cfe/trunk/lib/Frontend/CompilerInvocation.cpp

Modified: cfe/trunk/include/clang/Driver/CC1Options.td
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Driver/CC1Options.td?rev=298639&r1=298638&r2=298639&view=diff
==============================================================================
--- cfe/trunk/include/clang/Driver/CC1Options.td (original)
+++ cfe/trunk/include/clang/Driver/CC1Options.td Thu Mar 23 14:47:49 2017
@@ -312,6 +312,8 @@ def flto_visibility_public_std:
 def flto_unit: Flag<["-"], "flto-unit">,
     HelpText<"Emit IR to support LTO unit features (CFI, whole program vtable opt)">;
 def fno_lto_unit: Flag<["-"], "fno-lto-unit">;
+def fthin_link_bitcode_EQ : Joined<["-"], "fthin-link-bitcode=">,
+    HelpText<"Write minimized bitcode to <file> for the ThinLTO thin link only">;
 
 //===----------------------------------------------------------------------===//
 // Dependency Output Options

Modified: cfe/trunk/include/clang/Frontend/CodeGenOptions.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Frontend/CodeGenOptions.h?rev=298639&r1=298638&r2=298639&view=diff
==============================================================================
--- cfe/trunk/include/clang/Frontend/CodeGenOptions.h (original)
+++ cfe/trunk/include/clang/Frontend/CodeGenOptions.h Thu Mar 23 14:47:49 2017
@@ -188,6 +188,11 @@ public:
   /// importing.
   std::string ThinLTOIndexFile;
 
+  /// Name of a file that can optionally be written with minimized bitcode
+  /// to be used as input for the ThinLTO thin link step, which only needs
+  /// the summary and module symbol table (and not, e.g. any debug metadata).
+  std::string ThinLinkBitcodeFile;
+
   /// A list of file names passed with -fcuda-include-gpubinary options to
   /// forward to CUDA runtime back-end for incorporating them into host-side
   /// object file.

Modified: cfe/trunk/lib/CodeGen/BackendUtil.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/BackendUtil.cpp?rev=298639&r1=298638&r2=298639&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/BackendUtil.cpp (original)
+++ cfe/trunk/lib/CodeGen/BackendUtil.cpp Thu Mar 23 14:47:49 2017
@@ -686,13 +686,28 @@ void EmitAssemblyHelper::EmitAssembly(Ba
   CodeGenPasses.add(
       createTargetTransformInfoWrapperPass(getTargetIRAnalysis()));
 
+  std::unique_ptr<raw_fd_ostream> ThinLinkOS;
+
   switch (Action) {
   case Backend_EmitNothing:
     break;
 
   case Backend_EmitBC:
-    if (CodeGenOpts.EmitSummaryIndex)
-      PerModulePasses.add(createWriteThinLTOBitcodePass(*OS));
+    if (CodeGenOpts.EmitSummaryIndex) {
+      if (!CodeGenOpts.ThinLinkBitcodeFile.empty()) {
+        std::error_code EC;
+        ThinLinkOS.reset(new llvm::raw_fd_ostream(
+            CodeGenOpts.ThinLinkBitcodeFile, EC,
+            llvm::sys::fs::F_None));
+        if (EC) {
+          Diags.Report(diag::err_fe_unable_to_open_output) << CodeGenOpts.ThinLinkBitcodeFile
+                                                           << EC.message();
+          return;
+        }
+      }
+      PerModulePasses.add(
+          createWriteThinLTOBitcodePass(*OS, ThinLinkOS.get()));
+    }
     else
       PerModulePasses.add(
           createBitcodeWriterPass(*OS, CodeGenOpts.EmitLLVMUseLists));

Modified: cfe/trunk/lib/Frontend/CompilerInvocation.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Frontend/CompilerInvocation.cpp?rev=298639&r1=298638&r2=298639&view=diff
==============================================================================
--- cfe/trunk/lib/Frontend/CompilerInvocation.cpp (original)
+++ cfe/trunk/lib/Frontend/CompilerInvocation.cpp Thu Mar 23 14:47:49 2017
@@ -641,6 +641,7 @@ static bool ParseCodeGenArgs(CodeGenOpti
           << A->getAsString(Args) << "-x ir";
     Opts.ThinLTOIndexFile = Args.getLastArgValue(OPT_fthinlto_index_EQ);
   }
+  Opts.ThinLinkBitcodeFile = Args.getLastArgValue(OPT_fthin_link_bitcode_EQ);
 
   Opts.MSVolatile = Args.hasArg(OPT_fms_volatile);
 

Added: cfe/trunk/test/CodeGen/thin_link_bitcode.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/thin_link_bitcode.c?rev=298639&view=auto
==============================================================================
--- cfe/trunk/test/CodeGen/thin_link_bitcode.c (added)
+++ cfe/trunk/test/CodeGen/thin_link_bitcode.c Thu Mar 23 14:47:49 2017
@@ -0,0 +1,9 @@
+// RUN: %clang_cc1 -o %t -flto=thin -fthin-link-bitcode=%t.nodebug -triple x86_64-unknown-linux-gnu -emit-llvm-bc -debug-info-kind=limited %s
+// RUN: llvm-bcanalyzer -dump %t | FileCheck %s
+// RUN: llvm-bcanalyzer -dump %t.nodebug | FileCheck %s --check-prefix=NO_DEBUG
+int main (void) {
+  return 0;
+}
+
+// CHECK: COMPILE_UNIT
+// NO_DEBUG-NOT: COMPILE_UNIT