[PATCH] D18235: [LTO] Call the optimizer before invoking codegen

[Davide Italiano via llvm-commits]

davide created this revision.
davide added a reviewer: rafael.
davide added subscribers: llvm-commits, joker.eph, silvas.

This is the required plumbing needed to run the LTO passes.
Now the global constructor is (correctly) stripped away from the produced shared library.

http://reviews.llvm.org/D18235

Files:
  ELF/SymbolTable.cpp
  test/ELF/lto/ctors.ll

Index: test/ELF/lto/ctors.ll
===================================================================
--- test/ELF/lto/ctors.ll
+++ test/ELF/lto/ctors.ll
@@ -11,5 +11,5 @@
   ret void
 }
 
-; The llvm.global_ctors should end up producing constructors.
-; CHECK: Name: .ctors
+; The llvm.global_ctors should be stripped away.
+; CHECK-NOT: Name: .ctors
Index: ELF/SymbolTable.cpp
===================================================================
--- ELF/SymbolTable.cpp
+++ ELF/SymbolTable.cpp
@@ -18,12 +18,16 @@
 #include "Config.h"
 #include "Error.h"
 #include "Symbols.h"
+#include "llvm/Analysis/TargetLibraryInfo.h"
+#include "llvm/Analysis/TargetTransformInfo.h"
 #include "llvm/Bitcode/ReaderWriter.h"
 #include "llvm/IR/LegacyPassManager.h"
 #include "llvm/Linker/IRMover.h"
 #include "llvm/Support/StringSaver.h"
 #include "llvm/Support/TargetRegistry.h"
 #include "llvm/Target/TargetMachine.h"
+#include "llvm/Transforms/IPO.h"
+#include "llvm/Transforms/IPO/PassManagerBuilder.h"
 
 using namespace llvm;
 using namespace llvm::object;
@@ -106,6 +110,16 @@
   OS << Buffer;
 }
 
+// This is for use when debugging LTO.
+static void saveBCFile(Module &M, bool Optimized) {
+  std::error_code EC;
+  raw_fd_ostream OS(Config->OutputFile.str() +
+                    (Optimized ? ".lto.opt.bc" : ".lto.bc"), EC,
+                    sys::fs::OpenFlags::F_None);
+  check(EC);
+  WriteBitcodeToFile(&M, OS, /* ShouldPreserveUseListOrder */ true);
+}
+
 // Codegen the module M and returns the resulting InputFile.
 template <class ELFT>
 std::unique_ptr<InputFile> SymbolTable<ELFT>::codegen(Module &M) {
@@ -126,6 +140,24 @@
   std::unique_ptr<TargetMachine> TM(
       TheTarget->createTargetMachine(TripleStr, "", "", Options, R));
 
+  // LTOPasses.
+  M.setDataLayout(TM->createDataLayout());
+  legacy::PassManager ltoPasses;
+  ltoPasses.add(createTargetTransformInfoWrapperPass(TM->getTargetIRAnalysis()));
+  PassManagerBuilder PMB;
+  PMB.LibraryInfo = new TargetLibraryInfoImpl(Triple(TM->getTargetTriple()));
+  PMB.Inliner = createFunctionInliningPass();
+  PMB.VerifyInput = true;
+  PMB.VerifyOutput = true;
+  PMB.LoopVectorize = true;
+  PMB.SLPVectorize = true;
+  PMB.OptLevel = 2; // FIXME: This should be an option.
+  PMB.populateLTOPassManager(ltoPasses);
+  ltoPasses.run(*&M);
+
+  if (Config->SaveTemps)
+    saveBCFile(M, true /* Optimized */);
+
   raw_svector_ostream OS(OwningLTOData);
   legacy::PassManager CodeGenPasses;
   if (TM->addPassesToEmitFile(CodeGenPasses, OS,
@@ -169,15 +201,6 @@
              [](GlobalValue &, IRMover::ValueAdder) {});
 }
 
-// This is for use when debugging LTO.
-static void saveBCFile(Module &M) {
-  std::error_code EC;
-  raw_fd_ostream OS(Config->OutputFile.str() + ".lto.bc", 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>
@@ -188,7 +211,7 @@
   for (const std::unique_ptr<BitcodeFile> &F : BitcodeFiles)
     addBitcodeFile(Mover, *F, Context);
   if (Config->SaveTemps)
-    saveBCFile(Combined);
+    saveBCFile(Combined, false /* Optimized */);
   std::unique_ptr<InputFile> F = codegen(Combined);
   ObjectFiles.emplace_back(cast<ObjectFile<ELFT>>(F.release()));
   return &*ObjectFiles.back();


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