--- a/lib/Target/Hexagon/HexagonTargetObjectFile.cpp	Tue Jan 26 22:56:36 2016 +0900
+++ b/lib/Target/Hexagon/HexagonTargetObjectFile.cpp	Fri Nov 25 19:14:25 2016 +0900
@@ -1,4 +1,4 @@
-//===-- HexagonTargetObjectFile.cpp - Hexagon asm properties --------------===//
+//===-- HexagonTargetObjectFile.cpp ---------------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
@@ -10,10 +10,10 @@
 // This file contains the declarations of the HexagonTargetAsmInfo properties.
 //
 //===----------------------------------------------------------------------===//
+#define DEBUG_TYPE "hexagon-sdata"
 
+#include "HexagonTargetMachine.h"
 #include "HexagonTargetObjectFile.h"
-#include "HexagonSubtarget.h"
-#include "HexagonTargetMachine.h"
 #include "llvm/IR/DataLayout.h"
 #include "llvm/IR/DerivedTypes.h"
 #include "llvm/IR/Function.h"
@@ -24,75 +24,359 @@
 
 using namespace llvm;
 
-static cl::opt<int> SmallDataThreshold("hexagon-small-data-threshold",
-                                cl::init(8), cl::Hidden,
-                cl::desc("The maximum size of an object in the sdata section"));
+static cl::opt<unsigned> SmallDataThreshold("hexagon-small-data-threshold",
+  cl::init(8), cl::Hidden,
+  cl::desc("The maximum size of an object in the sdata section"));
+
+static cl::opt<bool> NoSmallDataSorting("mno-sort-sda", cl::init(false),
+  cl::Hidden, cl::desc("Disable small data sections sorting"));
+
+static cl::opt<bool> StaticsInSData("hexagon-statics-in-small-data",
+  cl::init(false), cl::Hidden, cl::ZeroOrMore,
+  cl::desc("Allow static variables in .sdata"));
+
+static cl::opt<bool> TraceGVPlacement("trace-gv-placement",
+  cl::Hidden, cl::init(false),
+  cl::desc("Trace global value placement"));
+
+// TraceGVPlacement controls messages for all builds. For builds with assertions
+// (debug or release), messages are also controlled by the usual debug flags
+// (e.g. -debug and -debug-only=globallayout)
+#define TRACE_TO(s, X) s << X
+#ifdef NDEBUG
+#define TRACE(X) do { if (TraceGVPlacement) { TRACE_TO(errs(), X); } } while (0)
+#else
+#define TRACE(X) \
+  do { \
+    if (TraceGVPlacement) { TRACE_TO(errs(), X); } \
+    else { DEBUG( TRACE_TO(dbgs(), X) ); } \
+  } while (0)
+#endif
+
+// Returns true if the section name is such that the symbol will be put
+// in a small data section.
+// For instance, global variables with section attributes such as ".sdata"
+// ".sdata.*", ".sbss", and ".sbss.*" will go into small data.
+static bool isSmallDataSection(StringRef Sec) {
+  // sectionName is either ".sdata" or ".sbss". Looking for an exact match
+  // obviates the need for checks for section names such as ".sdatafoo".
+  if (Sec.equals(".sdata") || Sec.equals(".sbss") || Sec.equals(".scommon"))
+    return true;
+  // If either ".sdata." or ".sbss." is a substring of the section name
+  // then put the symbol in small data.
+  return Sec.find(".sdata.") != StringRef::npos ||
+         Sec.find(".sbss.") != StringRef::npos ||
+         Sec.find(".scommon.") != StringRef::npos;
+}
+
+
+static const char *getSectionSuffixForSize(unsigned Size) {
+  switch (Size) {
+  default:
+    return "";
+  case 1:
+    return ".1";
+  case 2:
+    return ".2";
+  case 4:
+    return ".4";
+  case 8:
+    return ".8";
+  }
+}
 
 void HexagonTargetObjectFile::Initialize(MCContext &Ctx,
-                                         const TargetMachine &TM) {
+      const TargetMachine &TM) {
   TargetLoweringObjectFileELF::Initialize(Ctx, TM);
   InitializeELF(TM.Options.UseInitArray);
 
-  SmallDataSection = getContext().getELFSection(
-      ".sdata", ELF::SHT_PROGBITS, ELF::SHF_WRITE | ELF::SHF_ALLOC);
-  SmallBSSSection = getContext().getELFSection(".sbss", ELF::SHT_NOBITS,
-                                               ELF::SHF_WRITE | ELF::SHF_ALLOC);
+  SmallDataSection =
+    getContext().getELFSection(".sdata", ELF::SHT_PROGBITS,
+                               ELF::SHF_WRITE | ELF::SHF_ALLOC |
+                               ELF::SHF_HEX_GPREL);
+  SmallBSSSection =
+    getContext().getELFSection(".sbss", ELF::SHT_NOBITS,
+                               ELF::SHF_WRITE | ELF::SHF_ALLOC |
+                               ELF::SHF_HEX_GPREL);
+}
+
+MCSection *HexagonTargetObjectFile::SelectSectionForGlobal(
+    const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
+  TRACE("[SelectSectionForGlobal] GO(" << GO->getName() << ") ");
+  TRACE("input section(" << GO->getSection() << ") ");
+
+  TRACE((GO->hasPrivateLinkage() ? "private_linkage " : "")
+         << (GO->hasLocalLinkage() ? "local_linkage " : "")
+         << (GO->hasInternalLinkage() ? "internal " : "")
+         << (GO->hasExternalLinkage() ? "external " : "")
+         << (GO->hasCommonLinkage() ? "common_linkage " : "")
+         << (GO->hasCommonLinkage() ? "common " : "" )
+         << (Kind.isCommon() ? "kind_common " : "" )
+         << (Kind.isBSS() ? "kind_bss " : "" )
+         << (Kind.isBSSLocal() ? "kind_bss_local " : "" ));
+
+  if (isGlobalInSmallSection(GO, TM))
+    return selectSmallSectionForGlobal(GO, Kind, TM);
+
+  if (Kind.isCommon()) {
+    // This is purely for LTO+Linker Script because commons don't really have a
+    // section. However, the BitcodeSectionWriter pass will query for the
+    // sections of commons (and the linker expects us to know their section) so
+    // we'll return one here.
+    return BSSSection;
+  }
+
+  TRACE("default_ELF_section\n");
+  // Otherwise, we work the same as ELF.
+  return TargetLoweringObjectFileELF::SelectSectionForGlobal(GO, Kind, TM);
 }
 
-// sdata/sbss support taken largely from the MIPS Backend.
-static bool IsInSmallSection(uint64_t Size) {
-  return Size > 0 && Size <= (uint64_t)SmallDataThreshold;
+MCSection *HexagonTargetObjectFile::getExplicitSectionGlobal(
+    const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
+  TRACE("[getExplicitSectionGlobal] GO(" << GO->getName() << ") from("
+        << GO->getSection() << ") ");
+  TRACE((GO->hasPrivateLinkage() ? "private_linkage " : "")
+         << (GO->hasLocalLinkage() ? "local_linkage " : "")
+         << (GO->hasInternalLinkage() ? "internal " : "")
+         << (GO->hasExternalLinkage() ? "external " : "")
+         << (GO->hasCommonLinkage() ? "common_linkage " : "")
+         << (GO->hasCommonLinkage() ? "common " : "" )
+         << (Kind.isCommon() ? "kind_common " : "" )
+         << (Kind.isBSS() ? "kind_bss " : "" )
+         << (Kind.isBSSLocal() ? "kind_bss_local " : "" ));
+
+  if (GO->hasSection()) {
+    StringRef Section = GO->getSection();
+    if (Section.find(".access.text.group") != StringRef::npos)
+      return getContext().getELFSection(GO->getSection(), ELF::SHT_PROGBITS,
+                                        ELF::SHF_ALLOC | ELF::SHF_EXECINSTR);
+    if (Section.find(".access.data.group") != StringRef::npos)
+      return getContext().getELFSection(GO->getSection(), ELF::SHT_PROGBITS,
+                                        ELF::SHF_WRITE | ELF::SHF_ALLOC);
+  }
+
+  if (isGlobalInSmallSection(GO, TM))
+    return selectSmallSectionForGlobal(GO, Kind, TM);
+
+  // Otherwise, we work the same as ELF.
+  TRACE("default_ELF_section\n");
+  return TargetLoweringObjectFileELF::getExplicitSectionGlobal(GO, Kind, TM);
 }
 
-bool HexagonTargetObjectFile::IsSmallDataEnabled () const {
+
+/// Return true if this global value should be placed into small data/bss
+/// section.
+bool HexagonTargetObjectFile::isGlobalInSmallSection(const GlobalObject *GO,
+      const TargetMachine &TM) const {
+  // Only global variables, not functions.
+  DEBUG(dbgs() << "Checking if value is in small-data, -G"
+               << SmallDataThreshold << ": \"" << GO->getName() << "\": ");
+  const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GO);
+  if (!GVar) {
+    DEBUG(dbgs() << "no, not a global variable\n");
+    return false;
+  }
+
+  // Globals with external linkage that have an original section set must be
+  // emitted to that section, regardless of whether we would put them into
+  // small data or not. This is how we can support mixing -G0/-G8 in LTO.
+  if (GVar->hasSection()) {
+    bool IsSmall = isSmallDataSection(GVar->getSection());
+    DEBUG(dbgs() << (IsSmall ? "yes" : "no") << ", has section: "
+                 << GVar->getSection() << '\n');
+    return IsSmall;
+  }
+
+  if (GVar->isConstant()) {
+    DEBUG(dbgs() << "no, is a constant\n");
+    return false;
+  }
+
+  bool IsLocal = GVar->hasLocalLinkage();
+  if (!StaticsInSData && IsLocal) {
+    DEBUG(dbgs() << "no, is static\n");
+    return false;
+  }
+
+  Type *GType = GVar->getType();
+  if (PointerType *PT = dyn_cast<PointerType>(GType))
+    GType = PT->getElementType();
+
+  if (isa<ArrayType>(GType)) {
+    DEBUG(dbgs() << "no, is an array\n");
+    return false;
+  }
+
+  // If the type is a struct with no body provided, treat is conservatively.
+  // There cannot be actual definitions of object of such a type in this CU
+  // (only references), so assuming that they are not in sdata is safe. If
+  // these objects end up in the sdata, the references will still be valid.
+  if (StructType *ST = dyn_cast<StructType>(GType)) {
+    if (ST->isOpaque()) {
+      DEBUG(dbgs() << "no, has opaque type\n");
+      return false;
+    }
+  }
+
+  unsigned Size = GVar->getParent()->getDataLayout().getTypeAllocSize(GType);
+  if (Size == 0) {
+    DEBUG(dbgs() << "no, has size 0\n");
+    return false;
+  }
+  if (Size > SmallDataThreshold) {
+    DEBUG(dbgs() << "no, size exceeds sdata threshold: " << Size << '\n');
+    return false;
+  }
+
+  DEBUG(dbgs() << "yes\n");
+  return true;
+}
+
+
+bool HexagonTargetObjectFile::isSmallDataEnabled() const {
   return SmallDataThreshold > 0;
 }
 
-/// IsGlobalInSmallSection - Return true if this global value should be
-/// placed into small data/bss section.
-bool HexagonTargetObjectFile::IsGlobalInSmallSection(const GlobalValue *GV,
-                                                const TargetMachine &TM) const {
-  // If the primary definition of this global value is outside the current
-  // translation unit or the global value is available for inspection but not
-  // emission, then do nothing.
-  if (GV->isDeclaration() || GV->hasAvailableExternallyLinkage())
-    return false;
+
+unsigned HexagonTargetObjectFile::getSmallDataSize() const {
+  return SmallDataThreshold;
+}
+
+
+/// Descends any type down to "elementary" components,
+/// discovering the smallest addressable one.
+/// If zero is returned, declaration will not be modified.
+unsigned HexagonTargetObjectFile::getSmallestAddressableSize(const Type *Ty,
+      const GlobalValue *GV, const TargetMachine &TM) const {
+  // Assign the smallest element access size to the highest
+  // value which assembler can handle.
+  unsigned SmallestElement = 8;
 
-  // Otherwise, Check if GV should be in sdata/sbss, when normally it would end
-  // up in getKindForGlobal(GV, TM).
-  return IsGlobalInSmallSection(GV, TM, getKindForGlobal(GV, TM));
+  if (!Ty)
+    return 0;
+  switch (Ty->getTypeID()) {
+  case Type::StructTyID: {
+    const StructType *STy = cast<const StructType>(Ty);
+    for (auto &E : STy->elements()) {
+      unsigned AtomicSize = getSmallestAddressableSize(E, GV, TM);
+      if (AtomicSize < SmallestElement)
+        SmallestElement = AtomicSize;
+    }
+    return (STy->getNumElements() == 0) ? 0 : SmallestElement;
+  }
+  case Type::ArrayTyID: {
+    const ArrayType *ATy = cast<const ArrayType>(Ty);
+    return getSmallestAddressableSize(ATy->getElementType(), GV, TM);
+  }
+  case Type::VectorTyID: {
+    const VectorType *PTy = cast<const VectorType>(Ty);
+    return getSmallestAddressableSize(PTy->getElementType(), GV, TM);
+  }
+  case Type::PointerTyID:
+  case Type::HalfTyID:
+  case Type::FloatTyID:
+  case Type::DoubleTyID:
+  case Type::IntegerTyID: {
+    const DataLayout &DL = GV->getParent()->getDataLayout();
+    // It is unfortunate that DL's function take non-const Type*.
+    return DL.getTypeAllocSize(const_cast<Type*>(Ty));
+  }
+  case Type::FunctionTyID:
+  case Type::VoidTyID:
+  case Type::X86_FP80TyID:
+  case Type::FP128TyID:
+  case Type::PPC_FP128TyID:
+  case Type::LabelTyID:
+  case Type::MetadataTyID:
+  case Type::X86_MMXTyID:
+  case Type::TokenTyID:
+    return 0;
+  }
+
+  return 0;
 }
 
-/// IsGlobalInSmallSection - Return true if this global value should be
-/// placed into small data/bss section.
-bool HexagonTargetObjectFile::
-IsGlobalInSmallSection(const GlobalValue *GV, const TargetMachine &TM,
-                       SectionKind Kind) const {
-  // Only global variables, not functions.
-  const GlobalVariable *GVA = dyn_cast<GlobalVariable>(GV);
-  if (!GVA)
-    return false;
+MCSection *HexagonTargetObjectFile::selectSmallSectionForGlobal(
+    const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
+  const Type *GTy = GO->getType()->getElementType();
+  unsigned Size = getSmallestAddressableSize(GTy, GO, TM);
+
+  // If we have -ffunction-section or -fdata-section then we should emit the
+  // global value to a unique section specifically for it... even for sdata.
+  bool EmitUniquedSection = TM.getDataSections();
 
-  if (Kind.isBSS() || Kind.isData() || Kind.isCommon()) {
-    Type *Ty = GV->getValueType();
-    return IsInSmallSection(
-        GV->getParent()->getDataLayout().getTypeAllocSize(Ty));
+  TRACE("Small data. Size(" << Size << ")");
+  // Handle Small Section classification here.
+  if (Kind.isBSS() || Kind.isBSSLocal()) {
+    // If -mno-sort-sda is not set, find out smallest accessible entity in
+    // declaration and add it to the section name string.
+    // Note. It does not track the actual usage of the value, only its de-
+    // claration. Also, compiler adds explicit pad fields to some struct
+    // declarations - they are currently counted towards smallest addres-
+    // sable entity.
+    if (NoSmallDataSorting) {
+      TRACE(" default sbss\n");
+      return SmallBSSSection;
+    }
+
+    StringRef Prefix(".sbss");
+    SmallString<128> Name(Prefix);
+    Name.append(getSectionSuffixForSize(Size));
+
+    if (EmitUniquedSection) {
+      Name.append(".");
+      Name.append(GO->getName());
+    }
+    TRACE(" unique sbss(" << Name << ")\n");
+    return getContext().getELFSection(Name.str(), ELF::SHT_NOBITS,
+                ELF::SHF_WRITE | ELF::SHF_ALLOC | ELF::SHF_HEX_GPREL);
   }
 
-  return false;
-}
+  if (Kind.isCommon()) {
+    // This is purely for LTO+Linker Script because commons don't really have a
+    // section. However, the BitcodeSectionWriter pass will query for the
+    // sections of commons (and the linker expects us to know their section) so
+    // we'll return one here.
+    if (NoSmallDataSorting)
+      return BSSSection;
 
-MCSection *
-HexagonTargetObjectFile::SelectSectionForGlobal(const GlobalValue *GV,
-                                                SectionKind Kind, Mangler &Mang,
-                                                const TargetMachine &TM) const {
+    Twine Name = Twine(".scommon") + getSectionSuffixForSize(Size);
+    TRACE(" small COMMON (" << Name << ")\n");
+
+    return getContext().getELFSection(Name.str(), ELF::SHT_NOBITS,
+                                      ELF::SHF_WRITE | ELF::SHF_ALLOC |
+                                      ELF::SHF_HEX_GPREL);
+  }
 
-  // Handle Small Section classification here.
-  if (Kind.isBSS() && IsGlobalInSmallSection(GV, TM, Kind))
-    return SmallBSSSection;
-  if (Kind.isData() && IsGlobalInSmallSection(GV, TM, Kind))
-    return SmallDataSection;
+  // We could have changed sdata object to a constant... in this
+  // case the Kind could be wrong for it.
+  if (Kind.isMergeableConst()) {
+    TRACE(" const_object_as_data ");
+    const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GO);
+    if (GVar->hasSection() && isSmallDataSection(GVar->getSection()))
+      Kind = SectionKind::getData();
+  }
+
+  if (Kind.isData()) {
+    if (NoSmallDataSorting) {
+      TRACE(" default sdata\n");
+      return SmallDataSection;
+    }
 
+    StringRef Prefix(".sdata");
+    SmallString<128> Name(Prefix);
+    Name.append(getSectionSuffixForSize(Size));
+
+    if (EmitUniquedSection) {
+      Name.append(".");
+      Name.append(GO->getName());
+    }
+    TRACE(" unique sdata(" << Name << ")\n");
+    return getContext().getELFSection(Name.str(), ELF::SHT_PROGBITS,
+                ELF::SHF_WRITE | ELF::SHF_ALLOC | ELF::SHF_HEX_GPREL);
+  }
+
+  TRACE("default ELF section\n");
   // Otherwise, we work the same as ELF.
-  return TargetLoweringObjectFileELF::SelectSectionForGlobal(GV, Kind, Mang,TM);
+  return TargetLoweringObjectFileELF::SelectSectionForGlobal(GO, Kind, TM);
 }