[ThinLTO] Move summary computation from BitcodeWriter to new pass

Summary:
This is the first step in also serializing the index out to LLVM
assembly.

The per-module summary written to bitcode is moved out of the bitcode
writer and to a new analysis pass (ModuleSummaryIndexWrapperPass).
The pass itself uses a new builder class to compute index, and the
builder class is used directly in places where we don't have a pass
manager (e.g. llvm-as).

Because we are computing summaries outside of the bitcode writer, we no
longer can use value ids created by the bitcode writer's
ValueEnumerator. This required changing the reference graph edge type
to use a new ValueInfo class holding a union between a GUID (combined
index) and Value* (permodule index). The Value* are converted to the
appropriate value ID during bitcode writing.

Also, this enables removal of the BitWriter library's dependence on the
Analysis library that was previously required for the summary computation.

Reviewers: joker.eph

Subscribers: joker.eph, llvm-commits

Differential Revision: http://reviews.llvm.org/D18763

llvm-svn: 265941

1 files changed, 29 insertions, 3 deletions

diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriterPass.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriterPass.cpp
index 7dbede4..2eeeb5d 100644
--- a/llvm/lib/Bitcode/Writer/BitcodeWriterPass.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriterPass.cpp
@@ -12,6 +12,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Bitcode/BitcodeWriterPass.h"
+#include "llvm/Analysis/ModuleSummaryAnalysis.h"
 #include "llvm/Bitcode/ReaderWriter.h"
 #include "llvm/IR/Module.h"
 #include "llvm/IR/PassManager.h"
@@ -19,7 +20,11 @@
 using namespace llvm;
 
 PreservedAnalyses BitcodeWriterPass::run(Module &M) {
-  WriteBitcodeToFile(&M, OS, ShouldPreserveUseListOrder, EmitSummaryIndex, EmitModuleHash);
+  std::unique_ptr<ModuleSummaryIndex> Index;
+  if (EmitSummaryIndex)
+    Index = ModuleSummaryIndexBuilder(&M).takeIndex();
+  WriteBitcodeToFile(&M, OS, ShouldPreserveUseListOrder, Index.get(),
+                     EmitModuleHash);
   return PreservedAnalyses::all();
 }
 
@@ -32,22 +37,43 @@ namespace {
 
   public:
     static char ID; // Pass identification, replacement for typeid
+    WriteBitcodePass() : ModulePass(ID), OS(dbgs()) {
+      initializeWriteBitcodePassPass(*PassRegistry::getPassRegistry());
+    }
+
     explicit WriteBitcodePass(raw_ostream &o, bool ShouldPreserveUseListOrder,
                               bool EmitSummaryIndex, bool EmitModuleHash)
         : ModulePass(ID), OS(o),
           ShouldPreserveUseListOrder(ShouldPreserveUseListOrder),
-          EmitSummaryIndex(EmitSummaryIndex), EmitModuleHash(EmitModuleHash) {}
+          EmitSummaryIndex(EmitSummaryIndex), EmitModuleHash(EmitModuleHash) {
+      initializeWriteBitcodePassPass(*PassRegistry::getPassRegistry());
+    }
 
     const char *getPassName() const override { return "Bitcode Writer"; }
 
     bool runOnModule(Module &M) override {
-      WriteBitcodeToFile(&M, OS, ShouldPreserveUseListOrder, EmitSummaryIndex, EmitModuleHash);
+      const ModuleSummaryIndex *Index =
+          EmitSummaryIndex
+              ? &(getAnalysis<ModuleSummaryIndexWrapperPass>().getIndex())
+              : nullptr;
+      WriteBitcodeToFile(&M, OS, ShouldPreserveUseListOrder, Index,
+                         EmitModuleHash);
       return false;
     }
+    void getAnalysisUsage(AnalysisUsage &AU) const override {
+      AU.setPreservesAll();
+      if (EmitSummaryIndex)
+        AU.addRequired<ModuleSummaryIndexWrapperPass>();
+    }
   };
 }
 
 char WriteBitcodePass::ID = 0;
+INITIALIZE_PASS_BEGIN(WriteBitcodePass, "write-bitcode", "Write Bitcode", false,
+                      true)
+INITIALIZE_PASS_DEPENDENCY(ModuleSummaryIndexWrapperPass)
+INITIALIZE_PASS_END(WriteBitcodePass, "write-bitcode", "Write Bitcode", false,
+                    true)
 
 ModulePass *llvm::createBitcodeWriterPass(raw_ostream &Str,
                                           bool ShouldPreserveUseListOrder,