[JITLink][AArch32] Add dynamic lookup for relocation fixup infos

Author: weliveindetail

llvm/include/llvm/ExecutionEngine/JITLink/aarch32.h

@@ -98,6 +98,7 @@ enum EdgeKind_aarch32 : Edge::Kind {
   Thumb_MovtPrel,
 
   LastThumbRelocation = Thumb_MovtPrel,
+  LastRelocation = LastThumbRelocation,
 };
 
 /// Flags enum for AArch32-specific symbol properties
@@ -163,65 +164,109 @@ struct HalfWords {
   const uint16_t Lo; // Second halfword
 };
 
-/// Collection of named constants per fixup kind. It may contain but is not
-/// limited to the following entries:
+/// Initialize the lookup table for dynamic FixupInfo checks, e.g. checkOpcode()
+void populateFixupInfos();
+
+/// FixupInfo base class is required for dynamic lookups.
+struct FixupInfoBase {
+  virtual ~FixupInfoBase() {}
+};
+
+/// FixupInfo checks for Arm edge kinds work on 32-bit words
+struct FixupInfoArm : public FixupInfoBase {
+  bool (*checkOpcode)(uint32_t Wd) = nullptr;
+};
+
+/// FixupInfo check for Thumb32 edge kinds work on a pair of 16-bit halfwords
+struct FixupInfoThumb : public FixupInfoBase {
+  bool (*checkOpcode)(uint16_t Hi, uint16_t Lo) = nullptr;
+};
+
+/// Collection of named constants per fixup kind
 ///
+/// Mandatory entries:
 ///   Opcode      - Values of the op-code bits in the instruction, with
 ///                 unaffected bits nulled
 ///   OpcodeMask  - Mask with all bits set that encode the op-code
+///
+/// Other common entries:
 ///   ImmMask     - Mask with all bits set that encode the immediate value
 ///   RegMask     - Mask with all bits set that encode the register
 ///
+/// Specializations can add further custom fields without restrictions.
+///
 template <EdgeKind_aarch32 Kind> struct FixupInfo {};
 
-template <> struct FixupInfo<Arm_Jump24> {
+namespace {
+struct FixupInfoArmBranch : public FixupInfoArm {
   static constexpr uint32_t Opcode = 0x0a000000;
-  static constexpr uint32_t OpcodeMask = 0x0f000000;
   static constexpr uint32_t ImmMask = 0x00ffffff;
-  static constexpr uint32_t Unconditional = 0xe0000000;
-  static constexpr uint32_t CondMask = 0xe0000000; // excluding BLX bit
 };
+} // namespace
 
-template <> struct FixupInfo<Arm_Call> : public FixupInfo<Arm_Jump24> {
+template <> struct FixupInfo<Arm_Jump24> : public FixupInfoArmBranch {
+  static constexpr uint32_t OpcodeMask = 0x0f000000;
+};
+
+template <> struct FixupInfo<Arm_Call> : public FixupInfoArmBranch {
   static constexpr uint32_t OpcodeMask = 0x0e000000;
+  static constexpr uint32_t CondMask = 0xe0000000; // excluding BLX bit
+  static constexpr uint32_t Unconditional = 0xe0000000;
   static constexpr uint32_t BitH = 0x01000000;
   static constexpr uint32_t BitBlx = 0x10000000;
 };
 
-template <> struct FixupInfo<Arm_MovtAbs> {
-  static constexpr uint32_t Opcode = 0x03400000;
+namespace {
+struct FixupInfoArmMov : public FixupInfoArm {
   static constexpr uint32_t OpcodeMask = 0x0ff00000;
   static constexpr uint32_t ImmMask = 0x000f0fff;
   static constexpr uint32_t RegMask = 0x0000f000;
 };
+} // namespace
+
+template <> struct FixupInfo<Arm_MovtAbs> : public FixupInfoArmMov {
+  static constexpr uint32_t Opcode = 0x03400000;
+};
 
-template <> struct FixupInfo<Arm_MovwAbsNC> : public FixupInfo<Arm_MovtAbs> {
+template <> struct FixupInfo<Arm_MovwAbsNC> : public FixupInfoArmMov {
   static constexpr uint32_t Opcode = 0x03000000;
 };
 
-template <> struct FixupInfo<Thumb_Jump24> {
+template <> struct FixupInfo<Thumb_Jump24> : public FixupInfoThumb {
   static constexpr HalfWords Opcode{0xf000, 0x9000};
   static constexpr HalfWords OpcodeMask{0xf800, 0x9000};
   static constexpr HalfWords ImmMask{0x07ff, 0x2fff};
 };
 
-template <> struct FixupInfo<Thumb_Call> {
+template <> struct FixupInfo<Thumb_Call> : public FixupInfoThumb {
   static constexpr HalfWords Opcode{0xf000, 0xc000};
   static constexpr HalfWords OpcodeMask{0xf800, 0xc000};
   static constexpr HalfWords ImmMask{0x07ff, 0x2fff};
   static constexpr uint16_t LoBitH = 0x0001;
   static constexpr uint16_t LoBitNoBlx = 0x1000;
 };
 
-template <> struct FixupInfo<Thumb_MovtAbs> {
-  static constexpr HalfWords Opcode{0xf2c0, 0x0000};
+namespace {
+struct FixupInfoThumbMov : public FixupInfoThumb {
   static constexpr HalfWords OpcodeMask{0xfbf0, 0x8000};
   static constexpr HalfWords ImmMask{0x040f, 0x70ff};
   static constexpr HalfWords RegMask{0x0000, 0x0f00};
 };
+} // namespace
 
-template <>
-struct FixupInfo<Thumb_MovwAbsNC> : public FixupInfo<Thumb_MovtAbs> {
+template <> struct FixupInfo<Thumb_MovtAbs> : public FixupInfoThumbMov {
+  static constexpr HalfWords Opcode{0xf2c0, 0x0000};
+};
+
+template <> struct FixupInfo<Thumb_MovtPrel> : public FixupInfoThumbMov {
+  static constexpr HalfWords Opcode{0xf2c0, 0x0000};
+};
+
+template <> struct FixupInfo<Thumb_MovwAbsNC> : public FixupInfoThumbMov {
+  static constexpr HalfWords Opcode{0xf240, 0x0000};
+};
+
+template <> struct FixupInfo<Thumb_MovwPrelNC> : public FixupInfoThumbMov {
   static constexpr HalfWords Opcode{0xf240, 0x0000};
 };
 

llvm/lib/ExecutionEngine/JITLink/ELF_aarch32.cpp

@@ -232,6 +232,8 @@ createLinkGraphFromELFObject_aarch32(MemoryBufferRef ObjectBuffer) {
            << ObjectBuffer.getBufferIdentifier() << "...\n";
   });
 
+  aarch32::populateFixupInfos();
+
   auto ELFObj = ObjectFile::createELFObjectFile(ObjectBuffer);
   if (!ELFObj)
     return ELFObj.takeError();