[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

3 files changed, 11 insertions, 4 deletions

diff --git a/llvm/tools/llvm-as/CMakeLists.txt b/llvm/tools/llvm-as/CMakeLists.txt
index 1b2789a4de4..9b9027b7061 100644
--- a/llvm/tools/llvm-as/CMakeLists.txt
+++ b/llvm/tools/llvm-as/CMakeLists.txt
@@ -1,4 +1,5 @@
 set(LLVM_LINK_COMPONENTS
+  Analysis
   AsmParser
   BitWriter
   Core
diff --git a/llvm/tools/llvm-as/LLVMBuild.txt b/llvm/tools/llvm-as/LLVMBuild.txt
index 542470bbdd8..cef557ac7a2 100644
--- a/llvm/tools/llvm-as/LLVMBuild.txt
+++ b/llvm/tools/llvm-as/LLVMBuild.txt
@@ -19,4 +19,4 @@
 type = Tool
 name = llvm-as
 parent = Tools
-required_libraries = AsmParser BitWriter
+required_libraries = Analysis AsmParser BitWriter
diff --git a/llvm/tools/llvm-as/llvm-as.cpp b/llvm/tools/llvm-as/llvm-as.cpp
index 31010dbfac1..89397cde3ef 100644
--- a/llvm/tools/llvm-as/llvm-as.cpp
+++ b/llvm/tools/llvm-as/llvm-as.cpp
@@ -15,6 +15,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm/Analysis/ModuleSummaryAnalysis.h"
 #include "llvm/AsmParser/Parser.h"
 #include "llvm/Bitcode/ReaderWriter.h"
 #include "llvm/IR/LLVMContext.h"
@@ -83,9 +84,14 @@ static void WriteOutputFile(const Module *M) {
     exit(1);
   }
 
-  if (Force || !CheckBitcodeOutputToConsole(Out->os(), true))
-    WriteBitcodeToFile(M, Out->os(), PreserveBitcodeUseListOrder,
-                       EmitSummaryIndex, EmitModuleHash);
+  if (Force || !CheckBitcodeOutputToConsole(Out->os(), true)) {
+    std::unique_ptr<ModuleSummaryIndex> Index;
+    if (EmitSummaryIndex)
+      Index = ModuleSummaryIndexBuilder(M).takeIndex();
+
+    WriteBitcodeToFile(M, Out->os(), PreserveBitcodeUseListOrder, Index.get(),
+                       EmitModuleHash);
+  }
 
   // Declare success.
   Out->keep();