[ARM] Enable objdump to construct triple for ARM

Now that The ARMAttributeParser has been moved into the library,
it has been modified so that it can parse the attributes without
printing them and stores them in a map. ELFObjectFile now queries
the attributes to fill out the architecture details of a provided
triple for 'arm' and 'thumb' targets. llvm-objdump uses this new
functionality.

Differential Revision: https://reviews.llvm.org/D28281



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@291898 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Object/ELFObjectFile.h

@@ -26,6 +26,7 @@
 #include "llvm/Object/Error.h"
 #include "llvm/Object/ObjectFile.h"
 #include "llvm/Object/SymbolicFile.h"
+#include "llvm/Support/ARMAttributeParser.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/ELF.h"
 #include "llvm/Support/Endian.h"
@@ -72,6 +73,8 @@ class ELFObjectFileBase : public ObjectFile {
   static inline bool classof(const Binary *v) { return v->isELF(); }
 
   SubtargetFeatures getFeatures() const override;
+
+  void setARMSubArch(Triple &TheTriple) const override;
 };
 
 class ELFSectionRef : public SectionRef {
@@ -356,6 +359,28 @@ template <class ELFT> class ELFObjectFile : public ELFObjectFileBase {
     return std::error_code();
   }
 
+  std::error_code getBuildAttributes(ARMAttributeParser &Attributes) const override {
+    auto SectionsOrErr = EF.sections();
+    if (!SectionsOrErr)
+      return errorToErrorCode(SectionsOrErr.takeError());
+
+    for (const Elf_Shdr &Sec : *SectionsOrErr) {
+      if (Sec.sh_type == ELF::SHT_ARM_ATTRIBUTES) {
+        auto ErrorOrContents = EF.getSectionContents(&Sec);
+        if (!ErrorOrContents)
+          return errorToErrorCode(ErrorOrContents.takeError());
+
+        auto Contents = ErrorOrContents.get();
+        if (Contents[0] != ARMBuildAttrs::Format_Version || Contents.size() == 1)
+          return std::error_code();
+
+        Attributes.Parse(Contents, ELFT::TargetEndianness == support::little);
+        break;
+      }
+    }
+    return std::error_code();
+  }
+
   const ELFFile<ELFT> *getELFFile() const { return &EF; }
 
   bool isDyldType() const { return isDyldELFObject; }

include/llvm/Object/ObjectFile.h

@@ -24,6 +24,8 @@
 #include <cstring>
 
 namespace llvm {
+class ARMAttributeParser;
+
 namespace object {
 
 class ObjectFile;
@@ -265,13 +267,19 @@ class ObjectFile : public SymbolicFile {
   virtual StringRef getFileFormatName() const = 0;
   virtual /* Triple::ArchType */ unsigned getArch() const = 0;
   virtual SubtargetFeatures getFeatures() const = 0;
+  virtual void setARMSubArch(Triple &TheTriple) const { }
 
   /// Returns platform-specific object flags, if any.
   virtual std::error_code getPlatformFlags(unsigned &Result) const {
     Result = 0;
     return object_error::invalid_file_type;
   }
 
+  virtual std::error_code
+    getBuildAttributes(ARMAttributeParser &Attributes) const {
+      return std::error_code();
+    }
+
   /// True if this is a relocatable object (.o/.obj).
   virtual bool isRelocatableObject() const = 0;
 

include/llvm/Support/ARMAttributeParser.h

@@ -13,11 +13,15 @@
 #include "ARMBuildAttributes.h"
 #include "ScopedPrinter.h"
 
+#include <map>
+
 namespace llvm {
 class StringRef;
 
 class ARMAttributeParser {
-  ScopedPrinter &SW;
+  ScopedPrinter *SW;
+
+  std::map<unsigned, unsigned> Attributes;
 
   struct DisplayHandler {
     ARMBuildAttrs::AttrType Attribute;
@@ -115,9 +119,19 @@ class ARMAttributeParser {
                       SmallVectorImpl<uint8_t> &IndexList);
   void ParseSubsection(const uint8_t *Data, uint32_t Length);
 public:
-  ARMAttributeParser(ScopedPrinter &SW) : SW(SW) {}
+  ARMAttributeParser(ScopedPrinter *SW) : SW(SW) {}
+
+  ARMAttributeParser() : SW(nullptr) { }
+
+  void Parse(ArrayRef<uint8_t> Section, bool isLittle);
+
+  bool hasAttribute(unsigned Tag) const {
+    return Attributes.count(Tag);
+  }
 
-  void Parse(ArrayRef<uint8_t> Section);
+  unsigned getAttributeValue(unsigned Tag) const {
+    return Attributes.find(Tag)->second;
+  }
 };
 
 }

include/llvm/Support/ARMBuildAttributes.h

@@ -176,14 +176,25 @@ enum {
   WCharWidth2Bytes = 2, // sizeof(wchar_t) == 2
   WCharWidth4Bytes = 4, // sizeof(wchar_t) == 4
 
+  // Tag_ABI_align_needed, (=24), uleb128
+  Align8Byte = 1,
+  Align4Byte = 2,
+  AlignReserved = 3,
+
+  // Tag_ABI_align_needed, (=25), uleb128
+  AlignNotPreserved = 0,
+  AlignPreserve8Byte = 1,
+  AlignPreserveAll = 2,
+
   // Tag_ABI_FP_denormal, (=20), uleb128
   PositiveZero = 0,
   IEEEDenormals = 1,
   PreserveFPSign = 2, // sign when flushed-to-zero is preserved
 
   // Tag_ABI_FP_number_model, (=23), uleb128
+  AllowIEEENormal = 1,
   AllowRTABI = 2,  // numbers, infinities, and one quiet NaN (see [RTABI])
-  AllowIEE754 = 3, // this code to use all the IEEE 754-defined FP encodings
+  AllowIEEE754 = 3, // this code to use all the IEEE 754-defined FP encodings
 
   // Tag_ABI_enum_size, (=26), uleb128
   EnumProhibited = 0, // The user prohibited the use of enums when building
@@ -208,6 +219,7 @@ enum {
 
   // Tag_FP_16bit_format, (=38), uleb128
   FP16FormatIEEE = 1,
+  FP16VFP3 = 2,
 
   // Tag_MPextension_use, (=42), uleb128
   AllowMP = 1, // Allow use of MP extensions

lib/Object/ELFObjectFile.cpp

@@ -122,4 +122,69 @@ SubtargetFeatures ELFObjectFileBase::getFeatures() const {
   }
 }
 
+// FIXME Encode from a tablegen description or target parser.
+void ELFObjectFileBase::setARMSubArch(Triple &TheTriple) const {
+  if (TheTriple.getSubArch() != Triple::NoSubArch)
+    return;
+
+  ARMAttributeParser Attributes;
+  std::error_code EC = getBuildAttributes(Attributes);
+  if (EC)
+    return;
+
+  std::string Triple;
+  // Default to ARM, but use the triple if it's been set.
+  if (TheTriple.getArch() == Triple::thumb ||
+      TheTriple.getArch() == Triple::thumbeb)
+    Triple = "thumb";
+  else
+    Triple = "arm";
+
+  switch(Attributes.getAttributeValue(ARMBuildAttrs::CPU_arch)) {
+  case ARMBuildAttrs::v4:
+    Triple += "v4";
+    break;
+  case ARMBuildAttrs::v4T:
+    Triple += "v4t";
+    break;
+  case ARMBuildAttrs::v5T:
+    Triple += "v5t";
+    break;
+  case ARMBuildAttrs::v5TE:
+    Triple += "v5te";
+    break;
+  case ARMBuildAttrs::v5TEJ:
+    Triple += "v5tej";
+    break;
+  case ARMBuildAttrs::v6:
+    Triple += "v6";
+    break;
+  case ARMBuildAttrs::v6KZ:
+    Triple += "v6kz";
+    break;
+  case ARMBuildAttrs::v6T2:
+    Triple += "v6t2";
+    break;
+  case ARMBuildAttrs::v6K:
+    Triple += "v6k";
+    break;
+  case ARMBuildAttrs::v7:
+    Triple += "v7";
+    break;
+  case ARMBuildAttrs::v6_M:
+    Triple += "v6m";
+    break;
+  case ARMBuildAttrs::v6S_M:
+    Triple += "v6sm";
+    break;
+  case ARMBuildAttrs::v7E_M:
+    Triple += "v7em";
+    break;
+  }
+  if (!isLittleEndian())
+    Triple += "eb";
+
+  TheTriple.setArchName(Triple);
+}
+
 } // end namespace llvm