Subzero: Start writing out some relocation sections (text)

src/assembler_ia32.h

 //===- subzero/src/assembler_ia32.h - Assembler for x86-32 ------*- C++ -*-===//
 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 //
 // Modified by the Subzero authors.
 //
 //===----------------------------------------------------------------------===//
 //
 //                        The Subzero Code Generator
@@ skipping 14 matching lines @@
 #include "IceDefs.h"
 #include "IceOperand.h"
 #include "IceRegistersX8632.h"
 #include "IceTypes.h"
 #include "IceUtils.h"
 
 #include "assembler.h"
 
 namespace Ice {
 
-class Assembler;
-
 using RegX8632::GPRRegister;
 using RegX8632::XmmRegister;
 using RegX8632::ByteRegister;
 using RegX8632::X87STRegister;
 
 namespace x86 {
 
 const int MAX_NOP_SIZE = 8;
 
 enum ScaleFactor { TIMES_1 = 0, TIMES_2 = 1, TIMES_4 = 2, TIMES_8 = 3 };
 
-class DisplacementRelocation : public AssemblerFixup {
-  DisplacementRelocation(const DisplacementRelocation &) = delete;
-  DisplacementRelocation &operator=(const DisplacementRelocation &) = delete;
-
-public:
-  static DisplacementRelocation *create(Assembler *Asm, FixupKind Kind,
-                                        const Constant *Sym) {
-    return new (Asm->Allocate<DisplacementRelocation>())
-        DisplacementRelocation(Kind, Sym);
-  }
-
-private:
-  DisplacementRelocation(FixupKind Kind, const Constant *Sym)
-      : AssemblerFixup(Kind, Sym) {}
-};
-
 class Immediate {
   Immediate(const Immediate &) = delete;
   Immediate &operator=(const Immediate &) = delete;
 
 public:
   explicit Immediate(int32_t value) : value_(value), fixup_(nullptr) {}
 
   Immediate(RelocOffsetT offset, AssemblerFixup *fixup)
       : value_(offset), fixup_(fixup) {
-    // Use the Offset in the "value" for now. If the symbol is part of
-    // ".bss", then the relocation's symbol will be plain ".bss" and
-    // the value will need to be adjusted further to be sym's
-    // bss offset + Offset.
+    // Use the Offset in the "value" for now. If we decide to process fixups,
+    // we'll need to patch that offset with the true value.
   }
 
   int32_t value() const { return value_; }
   AssemblerFixup *fixup() const { return fixup_; }
 
   bool is_int8() const {
     // We currently only allow 32-bit fixups, and they usually have value = 0,
     // so if fixup_ != nullptr, it shouldn't be classified as int8/16.
     return fixup_ == nullptr && Utils::IsInt(8, value_);
   }
@@ skipping 159 matching lines @@
   static Address Absolute(const uintptr_t addr) {
     Address result;
     result.SetModRM(0, RegX8632::Encoded_Reg_ebp);
     result.SetDisp32(addr);
     return result;
   }
 
   static Address Absolute(RelocOffsetT Offset, AssemblerFixup *fixup) {
     Address result;
     result.SetModRM(0, RegX8632::Encoded_Reg_ebp);
-    // Use the Offset in the displacement for now. If the symbol is part of
-    // ".bss", then the relocation's symbol will be plain .bss and the
-    // displacement will need to be adjusted further to be sym's
-    // bss offset + Offset.
+    // Use the Offset in the displacement for now. If we decide to process
+    // fixups later, we'll need to patch up the emitted displacement.
     result.SetDisp32(Offset);
     result.SetFixup(fixup);
     return result;
   }
 
   static Address ofConstPool(Assembler *Asm, const Constant *Imm);
 
 private:
   Address() {} // Needed by Address::Absolute.
 };
@@ skipping 104 matching lines @@
   llvm::ArrayRef<uint8_t> getNonExecBundlePadding() const override {
     static const uint8_t Padding[] = {0xF4};
     return llvm::ArrayRef<uint8_t>(Padding, 1);
   }
 
   Label *GetOrCreateCfgNodeLabel(SizeT NodeNumber);
   void BindCfgNodeLabel(SizeT NodeNumber) override;
   Label *GetOrCreateLocalLabel(SizeT Number);
   void BindLocalLabel(SizeT Number);
 
+  bool fixupIsPCRel(FixupKind Kind) const override {
+    // Currently assuming this is the only PC-rel relocation type used.
+    return Kind == llvm::ELF::R_386_PC32;
+  }
+
   // Operations to emit GPR instructions (and dispatch on operand type).
   typedef void (AssemblerX86::*TypedEmitGPR)(Type, GPRRegister);
   typedef void (AssemblerX86::*TypedEmitAddr)(Type, const Address &);
   struct GPREmitterOneOp {
     TypedEmitGPR Reg;
     TypedEmitAddr Addr;
   };
 
   typedef void (AssemblerX86::*TypedEmitGPRGPR)(Type, GPRRegister, GPRRegister);
   typedef void (AssemblerX86::*TypedEmitGPRAddr)(Type, GPRRegister,
@@ skipping 489 matching lines @@
 inline void AssemblerX86::EmitFixup(AssemblerFixup *fixup) {
   buffer_.EmitFixup(fixup);
 }
 
 inline void AssemblerX86::EmitOperandSizeOverride() { EmitUint8(0x66); }
 
 } // end of namespace x86
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ASSEMBLER_IA32_H_