Infer relocation model from module flags in relocatable LTO link.

Fix for PR33096.

llvm-svn: 303578

include/llvm/LTO/Config.h

@@ -39,7 +39,7 @@ struct Config {
   std::string CPU;
   TargetOptions Options;
   std::vector<std::string> MAttrs;
-  Reloc::Model RelocModel = Reloc::PIC_;
+  Optional<Reloc::Model> RelocModel = Reloc::PIC_;
   CodeModel::Model CodeModel = CodeModel::Default;
   CodeGenOpt::Level CGOptLevel = CodeGenOpt::Default;
   TargetMachine::CodeGenFileType CGFileType = TargetMachine::CGFT_ObjectFile;

lib/LTO/LTO.cpp

@@ -114,7 +114,10 @@ static void computeCacheKey(
   AddUnsigned((unsigned)Conf.Options.DebuggerTuning);
   for (auto &A : Conf.MAttrs)
     AddString(A);
-  AddUnsigned(Conf.RelocModel);
+  if (Conf.RelocModel)
+    AddUnsigned(*Conf.RelocModel);
+  else
+    AddUnsigned(-1);
   AddUnsigned(Conf.CodeModel);
   AddUnsigned(Conf.CGOptLevel);
   AddUnsigned(Conf.CGFileType);

lib/LTO/LTOBackend.cpp

@@ -117,15 +117,22 @@ Error Config::addSaveTemps(std::string OutputFileName,
 namespace {
 
 std::unique_ptr<TargetMachine>
-createTargetMachine(Config &Conf, StringRef TheTriple,
-                    const Target *TheTarget) {
+createTargetMachine(Config &Conf, const Target *TheTarget, Module &M) {
+  StringRef TheTriple = M.getTargetTriple();
   SubtargetFeatures Features;
   Features.getDefaultSubtargetFeatures(Triple(TheTriple));
   for (const std::string &A : Conf.MAttrs)
     Features.AddFeature(A);
 
+  Reloc::Model RelocModel;
+  if (Conf.RelocModel)
+    RelocModel = *Conf.RelocModel;
+  else
+    RelocModel =
+        M.getPICLevel() == PICLevel::NotPIC ? Reloc::Static : Reloc::PIC_;
+
   return std::unique_ptr<TargetMachine>(TheTarget->createTargetMachine(
-      TheTriple, Conf.CPU, Features.getString(), Conf.Options, Conf.RelocModel,
+      TheTriple, Conf.CPU, Features.getString(), Conf.Options, RelocModel,
       Conf.CodeModel, Conf.CGOptLevel));
 }
 
@@ -311,7 +318,7 @@ void splitCodeGen(Config &C, TargetMachine *TM, AddStreamFn AddStream,
               std::unique_ptr<Module> MPartInCtx = std::move(MOrErr.get());
 
               std::unique_ptr<TargetMachine> TM =
-                  createTargetMachine(C, MPartInCtx->getTargetTriple(), T);
+                  createTargetMachine(C, T, *MPartInCtx);
 
               codegen(C, TM.get(), AddStream, ThreadId, *MPartInCtx);
             },
@@ -360,8 +367,7 @@ Error lto::backend(Config &C, AddStreamFn AddStream,
   if (!TOrErr)
     return TOrErr.takeError();
 
-  std::unique_ptr<TargetMachine> TM =
-      createTargetMachine(C, Mod->getTargetTriple(), *TOrErr);
+  std::unique_ptr<TargetMachine> TM = createTargetMachine(C, *TOrErr, *Mod);
 
   // Setup optimization remarks.
   auto DiagFileOrErr = lto::setupOptimizationRemarks(
@@ -397,8 +403,7 @@ Error lto::thinBackend(Config &Conf, unsigned Task, AddStreamFn AddStream,
   if (!TOrErr)
     return TOrErr.takeError();
 
-  std::unique_ptr<TargetMachine> TM =
-      createTargetMachine(Conf, Mod.getTargetTriple(), *TOrErr);
+  std::unique_ptr<TargetMachine> TM = createTargetMachine(Conf, *TOrErr, Mod);
 
   if (Conf.CodeGenOnly) {
     codegen(Conf, TM.get(), AddStream, Task, Mod);

test/tools/gold/X86/relocation-model-pic.ll

@@ -0,0 +1,63 @@
+; RUN: cat %s >%t.pic.ll
+; RUN: echo '!llvm.module.flags = !{!0}' >>%t.pic.ll
+; RUN: echo '!0 = !{i32 1, !"PIC Level", i32 2}' >>%t.pic.ll
+
+; RUN: llvm-as %s -o %t.o
+; RUN: llvm-as %t.pic.ll -o %t.pic.o
+
+;; Non-PIC source.
+
+; RUN: %gold -m elf_x86_64 -plugin %llvmshlibdir/LLVMgold.so \
+; RUN:    --shared \
+; RUN:    --plugin-opt=save-temps %t.o -o %t-out
+; RUN: llvm-readobj -r %t-out.o | FileCheck %s --check-prefix=PIC
+
+; RUN: %gold -m elf_x86_64 -plugin %llvmshlibdir/LLVMgold.so \
+; RUN:    --export-dynamic --noinhibit-exec -pie \
+; RUN:    --plugin-opt=save-temps %t.o -o %t-out
+; RUN: llvm-readobj -r %t-out.o | FileCheck %s --check-prefix=PIC
+
+; RUN: %gold -m elf_x86_64 -plugin %llvmshlibdir/LLVMgold.so \
+; RUN:    --export-dynamic --noinhibit-exec \
+; RUN:    --plugin-opt=save-temps %t.o -o %t-out
+; RUN: llvm-readobj -r %t-out.o | FileCheck %s --check-prefix=STATIC
+
+; RUN: %gold -m elf_x86_64 -plugin %llvmshlibdir/LLVMgold.so \
+; RUN:    -r \
+; RUN:    --plugin-opt=save-temps %t.o -o %t-out
+; RUN: llvm-readobj -r %t-out.o | FileCheck %s --check-prefix=STATIC
+
+;; PIC source.
+
+; RUN: %gold -m elf_x86_64 -plugin %llvmshlibdir/LLVMgold.so \
+; RUN:    --shared \
+; RUN:    --plugin-opt=save-temps %t.pic.o -o %t-out
+; RUN: llvm-readobj -r %t-out.o | FileCheck %s --check-prefix=PIC
+
+; RUN: %gold -m elf_x86_64 -plugin %llvmshlibdir/LLVMgold.so \
+; RUN:    --export-dynamic --noinhibit-exec -pie \
+; RUN:    --plugin-opt=save-temps %t.pic.o -o %t-out
+; RUN: llvm-readobj -r %t-out.o | FileCheck %s --check-prefix=PIC
+
+; RUN: %gold -m elf_x86_64 -plugin %llvmshlibdir/LLVMgold.so \
+; RUN:    --export-dynamic --noinhibit-exec \
+; RUN:    --plugin-opt=save-temps %t.pic.o -o %t-out
+; RUN: llvm-readobj -r %t-out.o | FileCheck %s --check-prefix=STATIC
+
+; RUN: %gold -m elf_x86_64 -plugin %llvmshlibdir/LLVMgold.so \
+; RUN:    -r \
+; RUN:    --plugin-opt=save-temps %t.pic.o -o %t-out
+; RUN: llvm-readobj -r %t-out.o | FileCheck %s --check-prefix=PIC
+
+
+; PIC: R_X86_64_GOTPCREL foo
+; STATIC: R_X86_64_PC32 foo
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@foo = external global i32
+define i32 @main() {
+  %t = load i32, i32* @foo
+  ret i32 %t
+}

tools/gold/gold-plugin.cpp

@@ -102,7 +102,7 @@ static ld_plugin_add_input_file add_input_file = nullptr;
 static ld_plugin_set_extra_library_path set_extra_library_path = nullptr;
 static ld_plugin_get_view get_view = nullptr;
 static bool IsExecutable = false;
-static Optional<Reloc::Model> RelocationModel;
+static Optional<Reloc::Model> RelocationModel = None;
 static std::string output_name = "";
 static std::list<claimed_file> Modules;
 static DenseMap<int, void *> FDToLeaderHandle;
@@ -282,6 +282,8 @@ ld_plugin_status onload(ld_plugin_tv *tv) {
     case LDPT_LINKER_OUTPUT:
       switch (tv->tv_u.tv_val) {
       case LDPO_REL: // .o
+        IsExecutable = false;
+        break;
       case LDPO_DYN: // .so
         IsExecutable = false;
         RelocationModel = Reloc::PIC_;
@@ -726,7 +728,7 @@ static std::unique_ptr<LTO> createLTO() {
   Conf.Options.RelaxELFRelocations = false;
 
   Conf.MAttrs = MAttrs;
-  Conf.RelocModel = *RelocationModel;
+  Conf.RelocModel = RelocationModel;
   Conf.CGOptLevel = getCGOptLevel();
   Conf.DisableVerify = options::DisableVerify;
   Conf.OptLevel = options::OptLevel;