[AMDGPU] Factored PAL metadata handling out into its own class

Summary:
This commit introduces a new AMDGPUPALMetadata class that:
* is inside the AMDGPU target;
* keeps an in-memory representation of PAL metadata;
* provides a method to read the frontend-supplied metadata from LLVM IR;
* provides methods for the asm printer to set metadata items;
* provides methods to write the metadata as a binary blob to put in a
  .note record or as an asm directive;
* provides a method to read the metadata as a binary blob from a .note
  record.

Because llvm-readobj cannot call directly into a target, I had to remove
llvm-readobj's ability to dump PAL metadata, pending a resolution to
https://reviews.llvm.org/D52821

Differential Revision: https://reviews.llvm.org/D57027

Change-Id: I756dc830894fcb6850324cdcfa87c0120eb2cf64
llvm-svn: 356582

2 files changed, 30 insertions, 31 deletions

diff --git a/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUTargetStreamer.cpp b/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUTargetStreamer.cpp
index 63737564b4a..f3b610a26db 100644
--- a/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUTargetStreamer.cpp
+++ b/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUTargetStreamer.cpp
@@ -153,6 +153,14 @@ AMDGPUTargetAsmStreamer::AMDGPUTargetAsmStreamer(MCStreamer &S,
                                                  formatted_raw_ostream &OS)
     : AMDGPUTargetStreamer(S), OS(OS) { }
 
+// A hook for emitting stuff at the end.
+// We use it for emitting the accumulated PAL metadata as directives.
+void AMDGPUTargetAsmStreamer::finish() {
+  std::string S;
+  getPALMetadata()->toString(S);
+  OS << S;
+}
+
 void AMDGPUTargetAsmStreamer::EmitDirectiveAMDGCNTarget(StringRef Target) {
   OS << "\t.amdgcn_target \"" << Target << "\"\n";
 }
@@ -225,16 +233,6 @@ bool AMDGPUTargetAsmStreamer::EmitHSAMetadata(
   return true;
 }
 
-bool AMDGPUTargetAsmStreamer::EmitPALMetadata(
-    const PALMD::Metadata &PALMetadata) {
-  std::string PALMetadataString;
-  if (PALMD::toString(PALMetadata, PALMetadataString))
-    return false;
-
-  OS << '\t' << PALMD::AssemblerDirective << PALMetadataString << '\n';
-  return true;
-}
-
 void AMDGPUTargetAsmStreamer::EmitAmdhsaKernelDescriptor(
     const MCSubtargetInfo &STI, StringRef KernelName,
     const amdhsa::kernel_descriptor_t &KD, uint64_t NextVGPR, uint64_t NextSGPR,
@@ -382,6 +380,19 @@ MCELFStreamer &AMDGPUTargetELFStreamer::getStreamer() {
   return static_cast<MCELFStreamer &>(Streamer);
 }
 
+// A hook for emitting stuff at the end.
+// We use it for emitting the accumulated PAL metadata as a .note record.
+void AMDGPUTargetELFStreamer::finish() {
+  std::string Blob;
+  unsigned Type = ELF::NT_AMD_AMDGPU_PAL_METADATA;
+  getPALMetadata()->toBlob(Type, Blob);
+  if (Blob.empty())
+    return;
+  EmitNote(ElfNote::NoteNameV2,
+           MCConstantExpr::create(Blob.size(), getContext()), Type,
+           [&](MCELFStreamer &OS) { OS.EmitBytes(Blob); });
+}
+
 void AMDGPUTargetELFStreamer::EmitNote(
     StringRef Name, const MCExpr *DescSZ, unsigned NoteType,
     function_ref<void(MCELFStreamer &)> EmitDesc) {
@@ -528,18 +539,6 @@ bool AMDGPUTargetELFStreamer::EmitHSAMetadata(
   return true;
 }
 
-bool AMDGPUTargetELFStreamer::EmitPALMetadata(
-    const PALMD::Metadata &PALMetadata) {
-  EmitNote(ElfNote::NoteNameV2,
-           MCConstantExpr::create(PALMetadata.size() * sizeof(uint32_t),
-                                  getContext()),
-           ELF::NT_AMD_AMDGPU_PAL_METADATA, [&](MCELFStreamer &OS) {
-             for (auto I : PALMetadata)
-               OS.EmitIntValue(I, sizeof(uint32_t));
-           });
-  return true;
-}
-
 void AMDGPUTargetELFStreamer::EmitAmdhsaKernelDescriptor(
     const MCSubtargetInfo &STI, StringRef KernelName,
     const amdhsa::kernel_descriptor_t &KernelDescriptor, uint64_t NextVGPR,
diff --git a/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUTargetStreamer.h b/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUTargetStreamer.h
index 5d9cb7cd59c..c1436b3585f 100644
--- a/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUTargetStreamer.h
+++ b/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUTargetStreamer.h
@@ -10,6 +10,7 @@
 #define LLVM_LIB_TARGET_AMDGPU_MCTARGETDESC_AMDGPUTARGETSTREAMER_H
 
 #include "AMDKernelCodeT.h"
+#include "Utils/AMDGPUPALMetadata.h"
 #include "llvm/BinaryFormat/MsgPackDocument.h"
 #include "llvm/MC/MCStreamer.h"
 #include "llvm/MC/MCSubtargetInfo.h"
@@ -28,12 +29,16 @@ class Module;
 class Type;
 
 class AMDGPUTargetStreamer : public MCTargetStreamer {
+  AMDGPUPALMetadata PALMetadata;
+
 protected:
   MCContext &getContext() const { return Streamer.getContext(); }
 
 public:
   AMDGPUTargetStreamer(MCStreamer &S) : MCTargetStreamer(S) {}
 
+  AMDGPUPALMetadata *getPALMetadata() { return &PALMetadata; }
+
   virtual void EmitDirectiveAMDGCNTarget(StringRef Target) = 0;
 
   virtual void EmitDirectiveHSACodeObjectVersion(uint32_t Major,
@@ -69,9 +74,6 @@ public:
   /// \returns True on success, false on failure.
   virtual bool EmitHSAMetadata(const AMDGPU::HSAMD::Metadata &HSAMetadata) = 0;
 
-  /// \returns True on success, false on failure.
-  virtual bool EmitPALMetadata(const AMDGPU::PALMD::Metadata &PALMetadata) = 0;
-
   virtual void EmitAmdhsaKernelDescriptor(
       const MCSubtargetInfo &STI, StringRef KernelName,
       const amdhsa::kernel_descriptor_t &KernelDescriptor, uint64_t NextVGPR,
@@ -87,6 +89,8 @@ class AMDGPUTargetAsmStreamer final : public AMDGPUTargetStreamer {
 public:
   AMDGPUTargetAsmStreamer(MCStreamer &S, formatted_raw_ostream &OS);
 
+  void finish() override;
+
   void EmitDirectiveAMDGCNTarget(StringRef Target) override;
 
   void EmitDirectiveHSACodeObjectVersion(uint32_t Major,
@@ -109,9 +113,6 @@ public:
   /// \returns True on success, false on failure.
   bool EmitHSAMetadata(const AMDGPU::HSAMD::Metadata &HSAMetadata) override;
 
-  /// \returns True on success, false on failure.
-  bool EmitPALMetadata(const AMDGPU::PALMD::Metadata &PALMetadata) override;
-
   void EmitAmdhsaKernelDescriptor(
       const MCSubtargetInfo &STI, StringRef KernelName,
       const amdhsa::kernel_descriptor_t &KernelDescriptor, uint64_t NextVGPR,
@@ -130,6 +131,8 @@ public:
 
   MCELFStreamer &getStreamer();
 
+  void finish() override;
+
   void EmitDirectiveAMDGCNTarget(StringRef Target) override;
 
   void EmitDirectiveHSACodeObjectVersion(uint32_t Major,
@@ -152,9 +155,6 @@ public:
   /// \returns True on success, false on failure.
   bool EmitHSAMetadata(const AMDGPU::HSAMD::Metadata &HSAMetadata) override;
 
-  /// \returns True on success, false on failure.
-  bool EmitPALMetadata(const AMDGPU::PALMD::Metadata &PALMetadata) override;
-
   void EmitAmdhsaKernelDescriptor(
       const MCSubtargetInfo &STI, StringRef KernelName,
       const amdhsa::kernel_descriptor_t &KernelDescriptor, uint64_t NextVGPR,