[AMDGPU] Implemented MCELFNoteDisassembler for PAL metadata note

[tpr]

Summary

Change-Id: I3749ab42309fd056f8cf5d58633891607b626820

[tpr]

Requires D52823. Currently no in-tree user of this code.

[arsenm]

lib/Target/AMDGPU/Disassembler/AMDGPUDisassembler.cpp

986–988

We can't just not work on big endian hosts. Can't you just use the utilities in Endian.h to support this?

989–990

I'd prefer to just do if (BYTE_ORDER == LITTLE_ENDIAN) inside

lib/Target/AMDGPU/Disassembler/AMDGPUDisassembler.h

184–185

No virtual

lib/Target/AMDGPU/Disassembler/AMDGPUDisassembler.h

 
 #ifndef LLVM_LIB_TARGET_AMDGPU_DISASSEMBLER_AMDGPUDISASSEMBLER_H
 #define LLVM_LIB_TARGET_AMDGPU_DISASSEMBLER_AMDGPUDISASSEMBLER_H
 
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/MC/MCContext.h"
 #include "llvm/MC/MCInstrInfo.h"
 #include "llvm/MC/MCDisassembler/MCDisassembler.h"
+#include "llvm/MC/MCDisassembler/MCELFNoteDisassembler.h"
 #include "llvm/MC/MCDisassembler/MCRelocationInfo.h"
 #include "llvm/MC/MCDisassembler/MCSymbolizer.h"
 #include "llvm/Object/ELFNoteDumper.h"
 
 #include <algorithm>
 #include <cstdint>
 #include <memory>
 
public:
   // note.
   // The .note descriptor (i.e. contents) is passed as an StringRef of bytes as
   // found in the ELF file, together with an indication of the endianness of
   // the ELF file.
   virtual bool dumpNote(unsigned Type, StringRef Name, StringRef Desc,
               support::endianness TargetEndianness, raw_ostream &OS) override;
 };
 
+//===----------------------------------------------------------------------===//
+// AMDGPUMCELFNoteDisassembler
+//===----------------------------------------------------------------------===//
+
+class AMDGPUMCELFNoteDisassembler : public MCELFNoteDisassembler {
+public:
+  AMDGPUMCELFNoteDisassembler(MCContext &Ctx, const MCSubtargetInfo *STI)
+      : MCELFNoteDisassembler(Ctx, STI) {}
+
+  // Disassemble one note from the ELF .note section.
+  // Returns false if the note type is not recognized or disassembly fails.
+  virtual bool disassembleNote(unsigned Type, StringRef Name, StringRef Desc,
+        support::endianness TargetEndianness, MCTargetStreamer *TS) override;
+};
+
 } // end namespace llvm
 
 #endif // LLVM_LIB_TARGET_AMDGPU_DISASSEMBLER_AMDGPUDISASSEMBLER_H

lib/Target/AMDGPU/Disassembler/AMDGPUDisassembler.cpp

#if BYTE_ORDER == LITTLE_ENDIAN
     return true;
 #endif
     return false;
   }
   }
 }
 
 //===----------------------------------------------------------------------===//
+// AMDGPUMCELFNoteDisassembler
+//===----------------------------------------------------------------------===//
+
+// Disassemble one note from the ELF .note section.
+// Returns false if the note type is not recognized or disassembly fails.
+bool AMDGPUMCELFNoteDisassembler::disassembleNote(unsigned Type, StringRef Name,
+        StringRef Desc, support::endianness TargetEndianness,
+        MCTargetStreamer *TS) {
+  if (Name != "AMD")
+    return false;
+  auto ATS = static_cast<AMDGPUTargetStreamer *>(TS);
+  switch (Type) {
+
+  // PAL metadata is in 32-bit words and only exists on AMDGPU, which is
+  // always little endian, so the following does not work if running
+  // llvm-readobj on a big-endian host.
+#if BYTE_ORDER == LITTLE_ENDIAN
+  case ELF::NT_AMD_AMDGPU_PAL_METADATA: {
+    ArrayRef<uint32_t> DescAsU32(
+          reinterpret_cast<const uint32_t *>(Desc.data()),
+          Desc.size() / sizeof(uint32_t));
+    AMDGPU::PALMD::Metadata MD(DescAsU32.begin(), DescAsU32.end());
+    ATS->EmitPALMetadata(MD);
+    ATS->getStreamer().AddBlankLine();
+    return true;
+  }
+#endif
+  return false;
+}
+
+//===----------------------------------------------------------------------===//
 // Initialization
 //===----------------------------------------------------------------------===//
 
 static MCSymbolizer *createAMDGPUSymbolizer(const Triple &/*TT*/,
                               LLVMOpInfoCallback /*GetOpInfo*/,
                               LLVMSymbolLookupCallback /*SymbolLookUp*/,
                               void *DisInfo,
                               MCContext *Ctx,
                               std::unique_ptr<MCRelocationInfo> &&RelInfo) {
   return new AMDGPUSymbolizer(*Ctx, std::move(RelInfo), DisInfo);
 }
 
 static MCDisassembler *createAMDGPUDisassembler(const Target &T,
                                                 const MCSubtargetInfo &STI,
                                                 MCContext &Ctx) {
   return new AMDGPUDisassembler(STI, Ctx, T.createMCInstrInfo());
 }
 
 static ELFNoteDumper *createAMDGPUELFNoteDumper(const Target &T) {
   return new AMDGPUELFNoteDumper();
 }
 
+static MCELFNoteDisassembler *createAMDGPUMCELFNoteDisassembler(const Target &T,
+                        MCContext &Ctx, const MCSubtargetInfo &STI) {
+  return new AMDGPUMCELFNoteDisassembler(Ctx, &STI);
+}
+
 extern "C" void LLVMInitializeAMDGPUDisassembler() {
   TargetRegistry::RegisterMCDisassembler(getTheGCNTarget(),
                                          createAMDGPUDisassembler);
   TargetRegistry::RegisterMCSymbolizer(getTheGCNTarget(),
                                        createAMDGPUSymbolizer);
   TargetRegistry::RegisterELFNoteDumper(getTheGCNTarget(),
                                         createAMDGPUELFNoteDumper);
+  TargetRegistry::RegisterMCELFNoteDisassembler(getTheGCNTarget(),
+                                            createAMDGPUMCELFNoteDisassembler);
 }