From 1e13d520887a1e46c28b9782848d0d796d8cb362 Mon Sep 17 00:00:00 2001
From: Shuxin Yang <shuxin.llvm@gmail.com>
Date: Mon, 22 Jul 2013 18:40:34 +0000
Subject: [PATCH] Initialize/Register LTO passes to enable flags like
 -print-after=<lto-pass>

There already have two "dead" functions, initialize{IPO|IPA}, defined for
similar purpose. I decide not to call these two functions for two reasons:
  o. they don't cover all LTO passes (which will soon be separated into IPO
     and post-IPO passes)
  o. We have not yet figured out the right passes and the ordering for IPO
     and post-IPO stages, meaning this change is only for the time being.

Since LTO passes are registered, we are now able to print IR before and
after particular point.

For OSX users:
--------------
  "...-Wl,-mllvm -Wl,-print-after=<pass-name>" will print IR after the
  specified pass.

For Other UNIX with GNU gold linker:
------------------------------------
  "-Wl,-plugin-opt=-print-after=<pass-name>" should work.
  (NOTE: no need for "-Wl,-mllvm")

  Strip "-Wl," if flags are fed directly to linker instead of clang/clang++.

llvm-svn: 186853
---
 tools/lto/LTOCodeGenerator.cpp | 32 ++++++++++++++++++++++++++++++++
 tools/lto/LTOCodeGenerator.h   |  2 ++
 2 files changed, 34 insertions(+)

diff --git a/tools/lto/LTOCodeGenerator.cpp b/tools/lto/LTOCodeGenerator.cpp
index c7d14afcf34..6db4f31a4e7 100644
--- a/tools/lto/LTOCodeGenerator.cpp
+++ b/tools/lto/LTOCodeGenerator.cpp
@@ -24,6 +24,7 @@
 #include "llvm/IR/DerivedTypes.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Module.h"
+#include "llvm/InitializePasses.h"
 #include "llvm/Linker.h"
 #include "llvm/MC/MCAsmInfo.h"
 #include "llvm/MC/MCContext.h"
@@ -77,6 +78,7 @@ LTOCodeGenerator::LTOCodeGenerator()
   InitializeAllTargets();
   InitializeAllTargetMCs();
   InitializeAllAsmPrinters();
+  initializeLTOPasses();
 }
 
 LTOCodeGenerator::~LTOCodeGenerator() {
@@ -89,6 +91,36 @@ LTOCodeGenerator::~LTOCodeGenerator() {
     free(*I);
 }
 
+// Initialize LTO passes. Please keep this funciton in sync with
+// PassManagerBuilder::populateLTOPassManager(), and  make sure all LTO
+// passes are initialized. 
+//
+void LTOCodeGenerator::initializeLTOPasses() {
+  PassRegistry &R = *PassRegistry::getPassRegistry();
+
+  initializeInternalizePassPass(R);
+  initializeIPSCCPPass(R);
+  initializeGlobalOptPass(R);
+  initializeConstantMergePass(R);
+  initializeDAHPass(R);
+  initializeInstCombinerPass(R);
+  initializeSimpleInlinerPass(R);
+  initializePruneEHPass(R);
+  initializeGlobalDCEPass(R);
+  initializeArgPromotionPass(R);
+  initializeJumpThreadingPass(R);
+  initializeSROAPass(R);
+  initializeSROA_DTPass(R);
+  initializeSROA_SSAUpPass(R);
+  initializeFunctionAttrsPass(R);
+  initializeGlobalsModRefPass(R);
+  initializeLICMPass(R);
+  initializeGVNPass(R);
+  initializeMemCpyOptPass(R);
+  initializeDCEPass(R);
+  initializeCFGSimplifyPassPass(R);
+}
+
 bool LTOCodeGenerator::addModule(LTOModule* mod, std::string& errMsg) {
   bool ret = _linker.linkInModule(mod->getLLVVMModule(), &errMsg);
 
diff --git a/tools/lto/LTOCodeGenerator.h b/tools/lto/LTOCodeGenerator.h
index a4ade9fd26c..bbe32397fbc 100644
--- a/tools/lto/LTOCodeGenerator.h
+++ b/tools/lto/LTOCodeGenerator.h
@@ -56,6 +56,8 @@ struct LTOCodeGenerator {
   void setCodeGenDebugOptions(const char *opts);
 
 private:
+  void initializeLTOPasses();
+
   bool generateObjectFile(llvm::raw_ostream &out, std::string &errMsg);
   void applyScopeRestrictions();
   void applyRestriction(llvm::GlobalValue &GV,