Backport .init_array/.fini_array work.

Android requires ".init_array" and ".fini_array" for
X86/MIPS as well, regardless the gcc version.  This
patch is basing on following patches:

commit d6b43a317e71246380db55a50b799b062b53cdce
Author: Rafael Espindola <rafael.espindola@gmail.com>
Date:   Tue Jun 19 00:48:28 2012 +0000

  Move the support for using .init_array from ARM to the generic
  TargetLoweringObjectFileELF. Use this to support it on X86. Unlike ARM,
  on X86 it is not easy to find out if .init_array should be used or not, so
  the decision is made via TargetOptions and defaults to off.

  Add a command line option to llc that enables it.

commit 8af669f2f1d92436fe6dc43144bb084a620e7516
Author: Rafael Espindola <rafael.espindola@gmail.com>
Date:   Tue Jun 19 01:26:10 2012 +0000

  Add a -fuse-init-array option to cc1 and map to the UseInitArray target
  option. On the driver, check if we are using libraries from gcc 4.7 or newer
  and if so pass -fuse-init-array to the frontend.
  The crtbegin*.o files in gcc 4.7 no longer call the constructors listed in
  .ctors, so we have to use .init_array.

11 files changed, 100 insertions, 54 deletions

diff --git a/include/llvm/CodeGen/TargetLoweringObjectFileImpl.h b/include/llvm/CodeGen/TargetLoweringObjectFileImpl.h
index 5a4213625ba..9849e92f7de 100644
--- a/include/llvm/CodeGen/TargetLoweringObjectFileImpl.h
+++ b/include/llvm/CodeGen/TargetLoweringObjectFileImpl.h
@@ -33,6 +33,8 @@ namespace llvm {
 
 
 class TargetLoweringObjectFileELF : public TargetLoweringObjectFile {
+  bool UseInitArray;
+
 public:
   virtual ~TargetLoweringObjectFileELF() {}
 
@@ -66,6 +68,7 @@ public:
   getCFIPersonalitySymbol(const GlobalValue *GV, Mangler *Mang,
                           MachineModuleInfo *MMI) const;
 
+  void InitializeELF(bool UseInitArray_);
   virtual const MCSection *
   getStaticCtorSection(unsigned Priority = 65535) const;
   virtual const MCSection *
diff --git a/include/llvm/Target/TargetOptions.h b/include/llvm/Target/TargetOptions.h
index 12a27573153..bc60673589f 100644
--- a/include/llvm/Target/TargetOptions.h
+++ b/include/llvm/Target/TargetOptions.h
@@ -43,7 +43,7 @@ namespace llvm {
           StackAlignmentOverride(0), RealignStack(true),
           DisableJumpTables(false), EnableFastISel(false),
           PositionIndependentExecutable(false), EnableSegmentedStacks(false),
-          TrapFuncName(""), FloatABIType(FloatABI::Default)
+          UseInitArray(false), TrapFuncName(""), FloatABIType(FloatABI::Default)
     {}
 
     /// PrintMachineCode - This flag is enabled when the -print-machineinstrs
@@ -172,6 +172,10 @@ namespace llvm {
 
     unsigned EnableSegmentedStacks : 1;
 
+    /// UseInitArray - Use .init_array instead of .ctors for static
+    /// constructors.
+    unsigned UseInitArray : 1;
+
     /// getTrapFunctionName - If this returns a non-empty string, this means
     /// isel should lower Intrinsic::trap to a call to the specified function
     /// name instead of an ISD::TRAP node.
diff --git a/lib/CodeGen/TargetLoweringObjectFileImpl.cpp b/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
index 9925185be12..3660cf7d84e 100644
--- a/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
+++ b/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
@@ -349,10 +349,17 @@ TargetLoweringObjectFileELF::getStaticCtorSection(unsigned Priority) const {
   if (Priority == 65535)
     return StaticCtorSection;
 
-  std::string Name = std::string(".ctors.") + utostr(65535 - Priority);
-  return getContext().getELFSection(Name, ELF::SHT_PROGBITS,
-                                    ELF::SHF_ALLOC |ELF::SHF_WRITE,
-                                    SectionKind::getDataRel());
+  if (UseInitArray) {
+    std::string Name = std::string(".init_array.") + utostr(Priority);
+    return getContext().getELFSection(Name, ELF::SHT_INIT_ARRAY,
+                                      ELF::SHF_ALLOC | ELF::SHF_WRITE,
+                                      SectionKind::getDataRel());
+  } else {
+    std::string Name = std::string(".ctors.") + utostr(65535 - Priority);
+    return getContext().getELFSection(Name, ELF::SHT_PROGBITS,
+                                      ELF::SHF_ALLOC |ELF::SHF_WRITE,
+                                      SectionKind::getDataRel());
+  }
 }
 
 const MCSection *
@@ -362,10 +369,35 @@ TargetLoweringObjectFileELF::getStaticDtorSection(unsigned Priority) const {
   if (Priority == 65535)
     return StaticDtorSection;
 
-  std::string Name = std::string(".dtors.") + utostr(65535 - Priority);
-  return getContext().getELFSection(Name, ELF::SHT_PROGBITS,
-                                    ELF::SHF_ALLOC |ELF::SHF_WRITE,
-                                    SectionKind::getDataRel());
+  if (UseInitArray) {
+    std::string Name = std::string(".fini_array.") + utostr(Priority);
+    return getContext().getELFSection(Name, ELF::SHT_FINI_ARRAY,
+                                      ELF::SHF_ALLOC | ELF::SHF_WRITE,
+                                      SectionKind::getDataRel());
+  } else {
+    std::string Name = std::string(".dtors.") + utostr(65535 - Priority);
+    return getContext().getELFSection(Name, ELF::SHT_PROGBITS,
+                                      ELF::SHF_ALLOC |ELF::SHF_WRITE,
+                                      SectionKind::getDataRel());
+  }
+}
+
+void
+TargetLoweringObjectFileELF::InitializeELF(bool UseInitArray_) {
+  UseInitArray = UseInitArray_;
+  if (!UseInitArray)
+    return;
+
+  StaticCtorSection =
+    getContext().getELFSection(".init_array", ELF::SHT_INIT_ARRAY,
+                               ELF::SHF_WRITE |
+                               ELF::SHF_ALLOC,
+                               SectionKind::getDataRel());
+  StaticDtorSection =
+    getContext().getELFSection(".fini_array", ELF::SHT_FINI_ARRAY,
+                               ELF::SHF_WRITE |
+                               ELF::SHF_ALLOC,
+                               SectionKind::getDataRel());
 }
 
 //===----------------------------------------------------------------------===//
diff --git a/lib/Target/ARM/ARMTargetObjectFile.cpp b/lib/Target/ARM/ARMTargetObjectFile.cpp
index a5ea1c202e2..3d85ca7d699 100644
--- a/lib/Target/ARM/ARMTargetObjectFile.cpp
+++ b/lib/Target/ARM/ARMTargetObjectFile.cpp
@@ -24,20 +24,11 @@ using namespace dwarf;
 
 void ARMElfTargetObjectFile::Initialize(MCContext &Ctx,
                                         const TargetMachine &TM) {
+  bool isAAPCS_ABI = TM.getSubtarget<ARMSubtarget>().isAAPCS_ABI();
   TargetLoweringObjectFileELF::Initialize(Ctx, TM);
-  isAAPCS_ABI = TM.getSubtarget<ARMSubtarget>().isAAPCS_ABI();
+  InitializeELF(isAAPCS_ABI);
 
   if (isAAPCS_ABI) {
-    StaticCtorSection =
-      getContext().getELFSection(".init_array", ELF::SHT_INIT_ARRAY,
-                                 ELF::SHF_WRITE |
-                                 ELF::SHF_ALLOC,
-                                 SectionKind::getDataRel());
-    StaticDtorSection =
-      getContext().getELFSection(".fini_array", ELF::SHT_FINI_ARRAY,
-                                 ELF::SHF_WRITE |
-                                 ELF::SHF_ALLOC,
-                                 SectionKind::getDataRel());
     LSDASection = NULL;
   }
 
@@ -47,33 +38,3 @@ void ARMElfTargetObjectFile::Initialize(MCContext &Ctx,
                                0,
                                SectionKind::getMetadata());
 }
-
-const MCSection *
-ARMElfTargetObjectFile::getStaticCtorSection(unsigned Priority) const {
-  if (!isAAPCS_ABI)
-    return TargetLoweringObjectFileELF::getStaticCtorSection(Priority);
-
-  if (Priority == 65535)
-    return StaticCtorSection;
-
-  // Emit ctors in priority order.
-  std::string Name = std::string(".init_array.") + utostr(Priority);
-  return getContext().getELFSection(Name, ELF::SHT_INIT_ARRAY,
-                                    ELF::SHF_ALLOC | ELF::SHF_WRITE,
-                                    SectionKind::getDataRel());
-}
-
-const MCSection *
-ARMElfTargetObjectFile::getStaticDtorSection(unsigned Priority) const {
-  if (!isAAPCS_ABI)
-    return TargetLoweringObjectFileELF::getStaticDtorSection(Priority);
-
-  if (Priority == 65535)
-    return StaticDtorSection;
-
-  // Emit dtors in priority order.
-  std::string Name = std::string(".fini_array.") + utostr(Priority);
-  return getContext().getELFSection(Name, ELF::SHT_FINI_ARRAY,
-                                    ELF::SHF_ALLOC | ELF::SHF_WRITE,
-                                    SectionKind::getDataRel());
-}
diff --git a/lib/Target/ARM/ARMTargetObjectFile.h b/lib/Target/ARM/ARMTargetObjectFile.h
index ff210604148..c6a7261439d 100644
--- a/lib/Target/ARM/ARMTargetObjectFile.h
+++ b/lib/Target/ARM/ARMTargetObjectFile.h
@@ -20,7 +20,6 @@ class TargetMachine;
 class ARMElfTargetObjectFile : public TargetLoweringObjectFileELF {
 protected:
   const MCSection *AttributesSection;
-  bool isAAPCS_ABI;
 public:
   ARMElfTargetObjectFile() :
     TargetLoweringObjectFileELF(),
@@ -32,9 +31,6 @@ public:
   virtual const MCSection *getAttributesSection() const {
     return AttributesSection;
   }
-
-  const MCSection * getStaticCtorSection(unsigned Priority) const;
-  const MCSection * getStaticDtorSection(unsigned Priority) const;
 };
 
 } // end namespace llvm
diff --git a/lib/Target/Mips/MipsTargetObjectFile.cpp b/lib/Target/Mips/MipsTargetObjectFile.cpp
index 04dc60aa6b4..4ee79e19c95 100644
--- a/lib/Target/Mips/MipsTargetObjectFile.cpp
+++ b/lib/Target/Mips/MipsTargetObjectFile.cpp
@@ -26,6 +26,7 @@ SSThreshold("mips-ssection-threshold", cl::Hidden,
 
 void MipsTargetObjectFile::Initialize(MCContext &Ctx, const TargetMachine &TM){
   TargetLoweringObjectFileELF::Initialize(Ctx, TM);
+  InitializeELF(TM.Options.UseInitArray);
 
   SmallDataSection =
     getContext().getELFSection(".sdata", ELF::SHT_PROGBITS,
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 04299f30080..eaebc595147 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -144,6 +144,8 @@ static TargetLoweringObjectFile *createTLOF(X86TargetMachine &TM) {
     return new TargetLoweringObjectFileMachO();
   }
 
+  if (Subtarget->isTargetLinux())
+    return new X86LinuxTargetObjectFile();
   if (Subtarget->isTargetELF())
     return new TargetLoweringObjectFileELF();
   if (Subtarget->isTargetCOFF() && !Subtarget->isTargetEnvMacho())
diff --git a/lib/Target/X86/X86TargetObjectFile.cpp b/lib/Target/X86/X86TargetObjectFile.cpp
index 718f35ea84a..b8d673facc8 100644
--- a/lib/Target/X86/X86TargetObjectFile.cpp
+++ b/lib/Target/X86/X86TargetObjectFile.cpp
@@ -9,12 +9,15 @@
 
 #include "X86TargetObjectFile.h"
 #include "X86TargetMachine.h"
+#include "llvm/ADT/StringExtras.h"
 #include "llvm/CodeGen/MachineModuleInfoImpls.h"
 #include "llvm/MC/MCContext.h"
 #include "llvm/MC/MCExpr.h"
+#include "llvm/MC/MCSectionELF.h"
 #include "llvm/MC/MCSectionMachO.h"
 #include "llvm/Target/Mangler.h"
 #include "llvm/Support/Dwarf.h"
+#include "llvm/Support/ELF.h"
 using namespace llvm;
 using namespace dwarf;
 
@@ -42,3 +45,9 @@ getCFIPersonalitySymbol(const GlobalValue *GV, Mangler *Mang,
                         MachineModuleInfo *MMI) const {
   return Mang->getSymbol(GV);
 }
+
+void
+X86LinuxTargetObjectFile::Initialize(MCContext &Ctx, const TargetMachine &TM) {
+  TargetLoweringObjectFileELF::Initialize(Ctx, TM);
+  InitializeELF(TM.Options.UseInitArray);
+}
diff --git a/lib/Target/X86/X86TargetObjectFile.h b/lib/Target/X86/X86TargetObjectFile.h
index a02a36809ef..7698b59d69a 100644
--- a/lib/Target/X86/X86TargetObjectFile.h
+++ b/lib/Target/X86/X86TargetObjectFile.h
@@ -32,6 +32,12 @@ namespace llvm {
                             MachineModuleInfo *MMI) const;
   };
 
+  /// X86LinuxTargetObjectFile - This implementation is used for linux x86
+  /// and x86-64.
+  class X86LinuxTargetObjectFile : public TargetLoweringObjectFileELF {
+    virtual void Initialize(MCContext &Ctx, const TargetMachine &TM);
+  };
+
 } // end namespace llvm
 
 #endif
diff --git a/test/CodeGen/X86/constructor.ll b/test/CodeGen/X86/constructor.ll
new file mode 100644
index 00000000000..f6dec160e91
--- /dev/null
+++ b/test/CodeGen/X86/constructor.ll
@@ -0,0 +1,27 @@
+; RUN: llc < %s | FileCheck --check-prefix=CTOR %s
+; RUN: llc -use-init-array < %s | FileCheck --check-prefix=INIT-ARRAY %s
+@llvm.global_ctors = appending global [2 x { i32, void ()* }] [{ i32, void ()* } { i32 65535, void ()* @f }, { i32, void ()* } { i32 15, void ()* @g }]
+
+define void @f() {
+entry:
+  ret void
+}
+
+define void @g() {
+entry:
+  ret void
+}
+
+; CTOR:		.section	.ctors.65520,"aw",@progbits
+; CTOR-NEXT:	.align	8
+; CTOR-NEXT:	.quad	g
+; CTOR-NEXT:	.section	.ctors,"aw",@progbits
+; CTOR-NEXT:	.align	8
+; CTOR-NEXT:	.quad	f
+
+; INIT-ARRAY:		.section	.init_array.15,"aw",@init_array
+; INIT-ARRAY-NEXT:	.align	8
+; INIT-ARRAY-NEXT:	.quad	g
+; INIT-ARRAY-NEXT:	.section	.init_array,"aw",@init_array
+; INIT-ARRAY-NEXT:	.align	8
+; INIT-ARRAY-NEXT:	.quad	f
diff --git a/tools/llc/llc.cpp b/tools/llc/llc.cpp
index ceff8a6c8cc..9660e95f545 100644
--- a/tools/llc/llc.cpp
+++ b/tools/llc/llc.cpp
@@ -249,6 +249,10 @@ SegmentedStacks("segmented-stacks",
   cl::desc("Use segmented stacks if possible."),
   cl::init(false));
 
+static cl::opt<bool>
+UseInitArray("use-init-array",
+  cl::desc("Use .init_array instead of .ctors."),
+  cl::init(false));
 
 // GetFileNameRoot - Helper function to get the basename of a filename.
 static inline std::string
@@ -448,6 +452,7 @@ int main(int argc, char **argv) {
   Options.TrapFuncName = TrapFuncName;
   Options.PositionIndependentExecutable = EnablePIE;
   Options.EnableSegmentedStacks = SegmentedStacks;
+  Options.UseInitArray = UseInitArray;
 
   std::auto_ptr<TargetMachine>
     target(TheTarget->createTargetMachine(TheTriple.getTriple(),