[BPF][DebugInfo] Show CO-RE relocations in llvm-objdump

Extend llvm-objdump to show CO-RE relocations when `-r` option is
passed and object file has .BTF and .BTF.ext sections.

For example, the following C program:

    #define __pai __attribute__((preserve_access_index))

    struct foo { int i; int j;} __pai;
    struct bar { struct foo f[7]; } __pai;
    extern void sink(void *);

    void root(struct bar *bar) {
      sink(&bar[2].f[3].j);
    }

Should lead to the following objdump output:

    $ clang --target=bpf -O2 -g t.c -c -o - | \
        llvm-objdump  --no-addresses --no-show-raw-insn -dr -

    ...
            r2 = 0x94
                    CO-RE <byte_off> [2] struct bar::[2].f[3].j (2:0:3:1)
            r1 += r2
            call -0x1
                    R_BPF_64_32     sink
            exit
    ...

More examples could be found in unit tests, see BTFParserTest.cpp.

To achieve this:
- Move CO-RE relocation kinds definitions from BPFCORE.h to BTF.h.
- Extend BTF.h with types derived from BTF::CommonType, e.g.
  BTF::IntType and BTF::StrutType, to allow dyn_cast() and access to
  type additional data.
- Extend BTFParser to load BTF type and relocation data.
- Modify llvm-objdump.cpp to create instance of BTFParser when
  disassembly of object file with BTF sections is processed and `-r`
  flag is supplied.

Additional information about CO-RE is available at [1].

[1] https://docs.kernel.org/bpf/llvm_reloc.html

Depends on D149058

Differential Revision: https://reviews.llvm.org/D150079

4 files changed, 25 insertions, 43 deletions

diff --git a/llvm/lib/Target/BPF/BPFAbstractMemberAccess.cpp b/llvm/lib/Target/BPF/BPFAbstractMemberAccess.cpp
index 9c99765..a878eaa 100644
--- a/llvm/lib/Target/BPF/BPFAbstractMemberAccess.cpp
+++ b/llvm/lib/Target/BPF/BPFAbstractMemberAccess.cpp
@@ -78,6 +78,7 @@
 #include "BPFCORE.h"
 #include "BPFTargetMachine.h"
 #include "llvm/BinaryFormat/Dwarf.h"
+#include "llvm/DebugInfo/BTF/BTF.h"
 #include "llvm/IR/DebugInfoMetadata.h"
 #include "llvm/IR/GlobalVariable.h"
 #include "llvm/IR/Instruction.h"
@@ -369,7 +370,7 @@ bool BPFAbstractMemberAccess::IsPreserveDIAccessIndexCall(const CallInst *Call,
     CInfo.Metadata = nullptr;
     // Check validity of info_kind as clang did not check this.
     uint64_t InfoKind = getConstant(Call->getArgOperand(1));
-    if (InfoKind >= BPFCoreSharedInfo::MAX_FIELD_RELOC_KIND)
+    if (InfoKind >= BTF::MAX_FIELD_RELOC_KIND)
       report_fatal_error("Incorrect info_kind for llvm.bpf.preserve.field.info intrinsic");
     CInfo.AccessIndex = InfoKind;
     return true;
@@ -383,11 +384,11 @@ bool BPFAbstractMemberAccess::IsPreserveDIAccessIndexCall(const CallInst *Call,
     if (Flag >= BPFCoreSharedInfo::MAX_PRESERVE_TYPE_INFO_FLAG)
       report_fatal_error("Incorrect flag for llvm.bpf.preserve.type.info intrinsic");
     if (Flag == BPFCoreSharedInfo::PRESERVE_TYPE_INFO_EXISTENCE)
-      CInfo.AccessIndex = BPFCoreSharedInfo::TYPE_EXISTENCE;
+      CInfo.AccessIndex = BTF::TYPE_EXISTENCE;
     else if (Flag == BPFCoreSharedInfo::PRESERVE_TYPE_INFO_MATCH)
-      CInfo.AccessIndex = BPFCoreSharedInfo::TYPE_MATCH;
+      CInfo.AccessIndex = BTF::TYPE_MATCH;
     else
-      CInfo.AccessIndex = BPFCoreSharedInfo::TYPE_SIZE;
+      CInfo.AccessIndex = BTF::TYPE_SIZE;
     return true;
   }
   if (GV->getName().startswith("llvm.bpf.preserve.enum.value")) {
@@ -399,9 +400,9 @@ bool BPFAbstractMemberAccess::IsPreserveDIAccessIndexCall(const CallInst *Call,
     if (Flag >= BPFCoreSharedInfo::MAX_PRESERVE_ENUM_VALUE_FLAG)
       report_fatal_error("Incorrect flag for llvm.bpf.preserve.enum.value intrinsic");
     if (Flag == BPFCoreSharedInfo::PRESERVE_ENUM_VALUE_EXISTENCE)
-      CInfo.AccessIndex = BPFCoreSharedInfo::ENUM_VALUE_EXISTENCE;
+      CInfo.AccessIndex = BTF::ENUM_VALUE_EXISTENCE;
     else
-      CInfo.AccessIndex = BPFCoreSharedInfo::ENUM_VALUE;
+      CInfo.AccessIndex = BTF::ENUM_VALUE;
     return true;
   }
 
@@ -672,11 +673,11 @@ uint32_t BPFAbstractMemberAccess::GetFieldInfo(uint32_t InfoKind,
                                                uint32_t AccessIndex,
                                                uint32_t PatchImm,
                                                MaybeAlign RecordAlignment) {
-  if (InfoKind == BPFCoreSharedInfo::FIELD_EXISTENCE)
-      return 1;
+  if (InfoKind == BTF::FIELD_EXISTENCE)
+    return 1;
 
   uint32_t Tag = CTy->getTag();
-  if (InfoKind == BPFCoreSharedInfo::FIELD_BYTE_OFFSET) {
+  if (InfoKind == BTF::FIELD_BYTE_OFFSET) {
     if (Tag == dwarf::DW_TAG_array_type) {
       auto *EltTy = stripQualifiers(CTy->getBaseType());
       PatchImm += AccessIndex * calcArraySize(CTy, 1) *
@@ -695,7 +696,7 @@ uint32_t BPFAbstractMemberAccess::GetFieldInfo(uint32_t InfoKind,
     return PatchImm;
   }
 
-  if (InfoKind == BPFCoreSharedInfo::FIELD_BYTE_SIZE) {
+  if (InfoKind == BTF::FIELD_BYTE_SIZE) {
     if (Tag == dwarf::DW_TAG_array_type) {
       auto *EltTy = stripQualifiers(CTy->getBaseType());
       return calcArraySize(CTy, 1) * (EltTy->getSizeInBits() >> 3);
@@ -715,7 +716,7 @@ uint32_t BPFAbstractMemberAccess::GetFieldInfo(uint32_t InfoKind,
     }
   }
 
-  if (InfoKind == BPFCoreSharedInfo::FIELD_SIGNEDNESS) {
+  if (InfoKind == BTF::FIELD_SIGNEDNESS) {
     const DIType *BaseTy;
     if (Tag == dwarf::DW_TAG_array_type) {
       // Signedness only checked when final array elements are accessed.
@@ -741,7 +742,7 @@ uint32_t BPFAbstractMemberAccess::GetFieldInfo(uint32_t InfoKind,
     return (Encoding == dwarf::DW_ATE_signed || Encoding == dwarf::DW_ATE_signed_char);
   }
 
-  if (InfoKind == BPFCoreSharedInfo::FIELD_LSHIFT_U64) {
+  if (InfoKind == BTF::FIELD_LSHIFT_U64) {
     // The value is loaded into a value with FIELD_BYTE_SIZE size,
     // and then zero or sign extended to U64.
     // FIELD_LSHIFT_U64 and FIELD_RSHIFT_U64 are operations
@@ -778,7 +779,7 @@ uint32_t BPFAbstractMemberAccess::GetFieldInfo(uint32_t InfoKind,
       return OffsetInBits + 64 - NextSBitOffset;
   }
 
-  if (InfoKind == BPFCoreSharedInfo::FIELD_RSHIFT_U64) {
+  if (InfoKind == BTF::FIELD_RSHIFT_U64) {
     DIDerivedType *MemberTy = nullptr;
     bool IsBitField = false;
     uint32_t SizeInBits;
@@ -849,7 +850,7 @@ Value *BPFAbstractMemberAccess::computeBaseAndAccessKey(CallInst *Call,
   // we will skip them.
   uint32_t FirstIndex = 0;
   uint32_t PatchImm = 0; // AccessOffset or the requested field info
-  uint32_t InfoKind = BPFCoreSharedInfo::FIELD_BYTE_OFFSET;
+  uint32_t InfoKind = BTF::FIELD_BYTE_OFFSET;
   while (CallStack.size()) {
     auto StackElem = CallStack.top();
     Call = StackElem.first;
@@ -939,7 +940,7 @@ Value *BPFAbstractMemberAccess::computeBaseAndAccessKey(CallInst *Call,
 
     if (CInfo.Kind == BPFPreserveFieldInfoAI) {
       InfoKind = CInfo.AccessIndex;
-      if (InfoKind == BPFCoreSharedInfo::FIELD_EXISTENCE)
+      if (InfoKind == BTF::FIELD_EXISTENCE)
         PatchImm = 1;
       break;
     }
@@ -987,10 +988,10 @@ MDNode *BPFAbstractMemberAccess::computeAccessKey(CallInst *Call,
 
   int64_t PatchImm;
   std::string AccessStr("0");
-  if (CInfo.AccessIndex == BPFCoreSharedInfo::TYPE_EXISTENCE ||
-      CInfo.AccessIndex == BPFCoreSharedInfo::TYPE_MATCH) {
+  if (CInfo.AccessIndex == BTF::TYPE_EXISTENCE ||
+      CInfo.AccessIndex == BTF::TYPE_MATCH) {
     PatchImm = 1;
-  } else if (CInfo.AccessIndex == BPFCoreSharedInfo::TYPE_SIZE) {
+  } else if (CInfo.AccessIndex == BTF::TYPE_SIZE) {
     // typedef debuginfo type has size 0, get the eventual base type.
     DIType *BaseTy = stripQualifiers(Ty, true);
     PatchImm = BaseTy->getSizeInBits() / 8;
@@ -1026,7 +1027,7 @@ MDNode *BPFAbstractMemberAccess::computeAccessKey(CallInst *Call,
       EnumIndex++;
     }
 
-    if (CInfo.AccessIndex == BPFCoreSharedInfo::ENUM_VALUE) {
+    if (CInfo.AccessIndex == BTF::ENUM_VALUE) {
       StringRef EValueStr = ValueStr.substr(Separator + 1);
       PatchImm = std::stoll(std::string(EValueStr));
     } else {
diff --git a/llvm/lib/Target/BPF/BPFCORE.h b/llvm/lib/Target/BPF/BPFCORE.h
index c9aa135..9a547a7 100644
--- a/llvm/lib/Target/BPF/BPFCORE.h
+++ b/llvm/lib/Target/BPF/BPFCORE.h
@@ -19,24 +19,6 @@ class Module;
 
 class BPFCoreSharedInfo {
 public:
-  enum PatchableRelocKind : uint32_t {
-    FIELD_BYTE_OFFSET = 0,
-    FIELD_BYTE_SIZE,
-    FIELD_EXISTENCE,
-    FIELD_SIGNEDNESS,
-    FIELD_LSHIFT_U64,
-    FIELD_RSHIFT_U64,
-    BTF_TYPE_ID_LOCAL,
-    BTF_TYPE_ID_REMOTE,
-    TYPE_EXISTENCE,
-    TYPE_SIZE,
-    ENUM_VALUE_EXISTENCE,
-    ENUM_VALUE,
-    TYPE_MATCH,
-
-    MAX_FIELD_RELOC_KIND,
-  };
-
   enum BTFTypeIdFlag : uint32_t {
     BTF_TYPE_ID_LOCAL_RELOC = 0,
     BTF_TYPE_ID_REMOTE_RELOC,
diff --git a/llvm/lib/Target/BPF/BPFPreserveDIType.cpp b/llvm/lib/Target/BPF/BPFPreserveDIType.cpp
index ec770ee..78e1bf9 100644
--- a/llvm/lib/Target/BPF/BPFPreserveDIType.cpp
+++ b/llvm/lib/Target/BPF/BPFPreserveDIType.cpp
@@ -13,6 +13,7 @@
 #include "BPF.h"
 #include "BPFCORE.h"
 #include "llvm/BinaryFormat/Dwarf.h"
+#include "llvm/DebugInfo/BTF/BTF.h"
 #include "llvm/IR/DebugInfoMetadata.h"
 #include "llvm/IR/GlobalVariable.h"
 #include "llvm/IR/Instruction.h"
@@ -82,9 +83,9 @@ static bool BPFPreserveDITypeImpl(Function &F) {
 
     uint32_t Reloc;
     if (FlagValue == BPFCoreSharedInfo::BTF_TYPE_ID_LOCAL_RELOC) {
-      Reloc = BPFCoreSharedInfo::BTF_TYPE_ID_LOCAL;
+      Reloc = BTF::BTF_TYPE_ID_LOCAL;
     } else {
-      Reloc = BPFCoreSharedInfo::BTF_TYPE_ID_REMOTE;
+      Reloc = BTF::BTF_TYPE_ID_REMOTE;
       DIType *Ty = cast<DIType>(MD);
       while (auto *DTy = dyn_cast<DIDerivedType>(Ty)) {
         unsigned Tag = DTy->getTag();
diff --git a/llvm/lib/Target/BPF/BTFDebug.cpp b/llvm/lib/Target/BPF/BTFDebug.cpp
index 2fe4206..f91ce7f 100644
--- a/llvm/lib/Target/BPF/BTFDebug.cpp
+++ b/llvm/lib/Target/BPF/BTFDebug.cpp
@@ -1518,10 +1518,8 @@ bool BTFDebug::InstLower(const MachineInstr *MI, MCInst &OutMI) {
           return false;
         }
 
-        if (Reloc == BPFCoreSharedInfo::ENUM_VALUE_EXISTENCE ||
-            Reloc == BPFCoreSharedInfo::ENUM_VALUE ||
-            Reloc == BPFCoreSharedInfo::BTF_TYPE_ID_LOCAL ||
-            Reloc == BPFCoreSharedInfo::BTF_TYPE_ID_REMOTE)
+        if (Reloc == BTF::ENUM_VALUE_EXISTENCE || Reloc == BTF::ENUM_VALUE ||
+            Reloc == BTF::BTF_TYPE_ID_LOCAL || Reloc == BTF::BTF_TYPE_ID_REMOTE)
           OutMI.setOpcode(BPF::LD_imm64);
         else
           OutMI.setOpcode(BPF::MOV_ri);