//===-------------------------- DwarfInstructions.hpp ---------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//
//  Processor specific interpretation of DWARF unwind info.
//
//===----------------------------------------------------------------------===//

#ifndef __DWARF_INSTRUCTIONS_HPP__
#define __DWARF_INSTRUCTIONS_HPP__

#include <cstdint>
#include <cstdlib>

#include "dwarf2.h"
#include "AddressSpace.hpp"
#include "Registers.hpp"
#include "DwarfParser.hpp"

namespace _Unwind {

enum step_result {
 UNW_STEP_SUCCESS,
 UNW_STEP_END,
 UNW_STEP_FAILED
};

/// DwarfInstructions maps abtract dwarf unwind instructions to a particular
/// architecture
template <typename A, typename R> class DwarfInstructions {
public:
 typedef typename A::pint_t pint_t;
 typedef typename A::sint_t sint_t;

 static step_result stepWithDwarf(A &, pint_t, pint_t, R &, unw_proc_info_t *);

private:
 static pint_t evaluateExpression(pint_t, A &, const R &, pint_t);
 static pint_t
 getSavedRegister(A &, const R &, pint_t,
                  const typename CFI_Parser<A, R>::RegisterLocation &);
 static pint_t
 computeRegisterLocation(A &, const R &, pint_t,
                         const typename CFI_Parser<A, R>::RegisterLocation &);

 static int lastRestoreReg(const R &) { return R::LAST_RESTORE_REG; }

 static pint_t getCFA(A &addressSpace,
                      const typename CFI_Parser<A, R>::PrologInfo &prolog,
                      const R &registers) {
   if (prolog.cfaRegister != 0)
     return registers.getRegister(prolog.cfaRegister) +
            prolog.cfaRegisterOffset;
   if (prolog.cfaExpression != 0)
     return evaluateExpression(prolog.cfaExpression, addressSpace, registers,
                               0);
   assert(0 && "getCFA(): unknown location");
   __builtin_unreachable();
 }
};

template <typename A, typename R>
typename A::pint_t DwarfInstructions<A, R>::getSavedRegister(
   A &addressSpace, const R &registers, pint_t cfa,
   const typename CFI_Parser<A, R>::RegisterLocation &savedReg) {
 switch (savedReg.location) {
 case CFI_Parser<A, R>::kRegisterInCFA:
   return addressSpace.getP(cfa + savedReg.value);

 case CFI_Parser<A, R>::kRegisterAtExpression:
   return addressSpace.getP(
       evaluateExpression(savedReg.value, addressSpace, registers, cfa));

 case CFI_Parser<A, R>::kRegisterIsExpression:
   return evaluateExpression(savedReg.value, addressSpace, registers, cfa);

 case CFI_Parser<A, R>::kRegisterInRegister:
   return registers.getRegister(savedReg.value);

 case CFI_Parser<A, R>::kRegisterUnused:
 case CFI_Parser<A, R>::kRegisterOffsetFromCFA:
   assert(0 && "unsupported restore location for register");
 }
 __builtin_unreachable();
}

template <typename A, typename R>
typename DwarfInstructions<A, R>::pint_t
DwarfInstructions<A, R>::computeRegisterLocation(
   A &addressSpace, const R &registers, pint_t cfa,
   const typename CFI_Parser<A, R>::RegisterLocation &savedReg) {
 switch (savedReg.location) {
 case CFI_Parser<A, R>::kRegisterInCFA:
   return cfa + savedReg.value;

 case CFI_Parser<A, R>::kRegisterAtExpression:
   return evaluateExpression(savedReg.value, addressSpace, registers, cfa);

 case CFI_Parser<A, R>::kRegisterIsExpression:
 case CFI_Parser<A, R>::kRegisterUnused:
 case CFI_Parser<A, R>::kRegisterOffsetFromCFA:
 case CFI_Parser<A, R>::kRegisterInRegister:
   assert(0 && "unsupported restore location for float/vector register");
 }
 __builtin_unreachable();
}

template <typename A, typename R>
step_result DwarfInstructions<A, R>::stepWithDwarf(A &addressSpace, pint_t pc,
                                                  pint_t fdeStart,
                                                  R &registers,
                                                  unw_proc_info_t *ctx) {
 typename CFI_Parser<A, R>::FDE_Info fdeInfo;
 typename CFI_Parser<A, R>::CIE_Info cieInfo;
 if (!CFI_Parser<A, R>::decodeFDE(addressSpace, fdeStart, &fdeInfo, &cieInfo,
                                  ctx))
   return UNW_STEP_FAILED;

 typename CFI_Parser<A, R>::PrologInfo prolog;
 if (!CFI_Parser<A, R>::parseFDEInstructions(addressSpace, fdeInfo, cieInfo,
                                             pc, &prolog, ctx))
   return UNW_STEP_FAILED;

 // Create working copy of the register set.
 R newRegisters = registers;

 // Get pointer to CFA by the architecture-specific code.
 pint_t cfa = getCFA(addressSpace, prolog, registers);

 // Restore registers according to DWARF instructions
 pint_t returnAddress = 0;
 for (int i = 0; i <= lastRestoreReg(newRegisters); ++i) {
   if (prolog.savedRegisters[i].location == CFI_Parser<A, R>::kRegisterUnused)
     continue;
   if (i == (int)cieInfo.returnAddressRegister)
     returnAddress = getSavedRegister(addressSpace, registers, cfa,
                                      prolog.savedRegisters[i]);
   else if (registers.validRegister(i))
     newRegisters.setRegister(i, getSavedRegister(addressSpace, registers, cfa,
                                                  prolog.savedRegisters[i]));
   else if (registers.validFloatVectorRegister(i))
     newRegisters.copyFloatVectorRegister(
         i, computeRegisterLocation(addressSpace, registers, cfa,
                                    prolog.savedRegisters[i]));
   else
     return UNW_STEP_FAILED;
 }

 // The CFA is defined as the stack pointer at the call site.
 // Therefore the SP is restored by setting it to the CFA.
 newRegisters.setSP(cfa);
 returnAddress += R::RETURN_OFFSET;
 returnAddress &= ~R::RETURN_MASK;
 newRegisters.setIP(returnAddress);

 // Now replace register set with the working copy.
 registers = newRegisters;

 return UNW_STEP_SUCCESS;
}

template <typename A, typename R>
typename A::pint_t
DwarfInstructions<A, R>::evaluateExpression(pint_t expression, A &addressSpace,
                                           const R &registers,
                                           pint_t initialStackValue) {
 pint_t p = expression;
 pint_t expressionEnd = expression + 20; // Rough estimate
 uint64_t length = addressSpace.getULEB128(p, expressionEnd);
 expressionEnd = p + length;
 pint_t stack[100];
 pint_t *sp = stack;
 *(++sp) = initialStackValue;

 while (p < expressionEnd) {
   uint8_t opcode = addressSpace.get8(p++);
   sint_t svalue;
   pint_t value;
   uint32_t reg;
   switch (opcode) {
   case DW_OP_addr:
     // push immediate address sized value
     value = addressSpace.getP(p);
     p += sizeof(pint_t);
     *(++sp) = value;
     break;

   case DW_OP_deref:
     // pop stack, dereference, push result
     value = *sp--;
     *(++sp) = addressSpace.getP(value);
     break;

   case DW_OP_const1u:
     // push immediate 1 byte value
     value = addressSpace.get8(p);
     p += 1;
     *(++sp) = value;
     break;

   case DW_OP_const1s:
     // push immediate 1 byte signed value
     svalue = (int8_t)addressSpace.get8(p);
     p += 1;
     *(++sp) = svalue;
     break;

   case DW_OP_const2u:
     // push immediate 2 byte value
     value = addressSpace.get16(p);
     p += 2;
     *(++sp) = value;
     break;

   case DW_OP_const2s:
     // push immediate 2 byte signed value
     svalue = (int16_t)addressSpace.get16(p);
     p += 2;
     *(++sp) = svalue;
     break;

   case DW_OP_const4u:
     // push immediate 4 byte value
     value = addressSpace.get32(p);
     p += 4;
     *(++sp) = value;
     break;

   case DW_OP_const4s:
     // push immediate 4 byte signed value
     svalue = (int32_t)addressSpace.get32(p);
     p += 4;
     *(++sp) = svalue;
     break;

   case DW_OP_const8u:
     // push immediate 8 byte value
     value = addressSpace.get64(p);
     p += 8;
     *(++sp) = value;
     break;

   case DW_OP_const8s:
     // push immediate 8 byte signed value
     value = (int32_t)addressSpace.get64(p);
     p += 8;
     *(++sp) = value;
     break;

   case DW_OP_constu:
     // push immediate ULEB128 value
     value = addressSpace.getULEB128(p, expressionEnd);
     *(++sp) = value;
     break;

   case DW_OP_consts:
     // push immediate SLEB128 value
     svalue = addressSpace.getSLEB128(p, expressionEnd);
     *(++sp) = svalue;
     break;

   case DW_OP_dup:
     // push top of stack
     value = *sp;
     *(++sp) = value;
     break;

   case DW_OP_drop:
     // pop
     --sp;
     break;

   case DW_OP_over:
     // dup second
     value = sp[-1];
     *(++sp) = value;
     break;

   case DW_OP_pick:
     // pick from
     reg = addressSpace.get8(p);
     p += 1;
     value = sp[-reg];
     *(++sp) = value;
     break;

   case DW_OP_swap:
     // swap top two
     value = sp[0];
     sp[0] = sp[-1];
     sp[-1] = value;
     break;

   case DW_OP_rot:
     // rotate top three
     value = sp[0];
     sp[0] = sp[-1];
     sp[-1] = sp[-2];
     sp[-2] = value;
     break;

   case DW_OP_xderef:
     // pop stack, dereference, push result
     value = *sp--;
     *sp = *((uint64_t *)value);
     break;

   case DW_OP_abs:
     svalue = *sp;
     if (svalue < 0)
       *sp = -svalue;
     break;

   case DW_OP_and:
     value = *sp--;
     *sp &= value;
     break;

   case DW_OP_div:
     svalue = *sp--;
     *sp = *sp / svalue;
     break;

   case DW_OP_minus:
     svalue = *sp--;
     *sp = *sp - svalue;
     break;

   case DW_OP_mod:
     svalue = *sp--;
     *sp = *sp % svalue;
     break;

   case DW_OP_mul:
     svalue = *sp--;
     *sp = *sp * svalue;
     break;

   case DW_OP_neg:
     *sp = 0 - *sp;
     break;

   case DW_OP_not:
     svalue = *sp;
     *sp = ~svalue;
     break;

   case DW_OP_or:
     value = *sp--;
     *sp |= value;
     break;

   case DW_OP_plus:
     value = *sp--;
     *sp += value;
     break;

   case DW_OP_plus_uconst:
     // pop stack, add uelb128 constant, push result
     *sp += addressSpace.getULEB128(p, expressionEnd);
     break;

   case DW_OP_shl:
     value = *sp--;
     *sp = *sp << value;
     break;

   case DW_OP_shr:
     value = *sp--;
     *sp = *sp >> value;
     break;

   case DW_OP_shra:
     value = *sp--;
     svalue = *sp;
     *sp = svalue >> value;
     break;

   case DW_OP_xor:
     value = *sp--;
     *sp ^= value;
     break;

   case DW_OP_skip:
     svalue = (int16_t)addressSpace.get16(p);
     p += 2;
     p += svalue;
     break;

   case DW_OP_bra:
     svalue = (int16_t)addressSpace.get16(p);
     p += 2;
     if (*sp--)
       p += svalue;
     break;

   case DW_OP_eq:
     value = *sp--;
     *sp = (*sp == value);
     break;

   case DW_OP_ge:
     value = *sp--;
     *sp = (*sp >= value);
     break;

   case DW_OP_gt:
     value = *sp--;
     *sp = (*sp > value);
     break;

   case DW_OP_le:
     value = *sp--;
     *sp = (*sp <= value);
     break;

   case DW_OP_lt:
     value = *sp--;
     *sp = (*sp < value);
     break;

   case DW_OP_ne:
     value = *sp--;
     *sp = (*sp != value);
     break;

   case DW_OP_lit0:
   case DW_OP_lit1:
   case DW_OP_lit2:
   case DW_OP_lit3:
   case DW_OP_lit4:
   case DW_OP_lit5:
   case DW_OP_lit6:
   case DW_OP_lit7:
   case DW_OP_lit8:
   case DW_OP_lit9:
   case DW_OP_lit10:
   case DW_OP_lit11:
   case DW_OP_lit12:
   case DW_OP_lit13:
   case DW_OP_lit14:
   case DW_OP_lit15:
   case DW_OP_lit16:
   case DW_OP_lit17:
   case DW_OP_lit18:
   case DW_OP_lit19:
   case DW_OP_lit20:
   case DW_OP_lit21:
   case DW_OP_lit22:
   case DW_OP_lit23:
   case DW_OP_lit24:
   case DW_OP_lit25:
   case DW_OP_lit26:
   case DW_OP_lit27:
   case DW_OP_lit28:
   case DW_OP_lit29:
   case DW_OP_lit30:
   case DW_OP_lit31:
     value = opcode - DW_OP_lit0;
     *(++sp) = value;
     break;

   case DW_OP_reg0:
   case DW_OP_reg1:
   case DW_OP_reg2:
   case DW_OP_reg3:
   case DW_OP_reg4:
   case DW_OP_reg5:
   case DW_OP_reg6:
   case DW_OP_reg7:
   case DW_OP_reg8:
   case DW_OP_reg9:
   case DW_OP_reg10:
   case DW_OP_reg11:
   case DW_OP_reg12:
   case DW_OP_reg13:
   case DW_OP_reg14:
   case DW_OP_reg15:
   case DW_OP_reg16:
   case DW_OP_reg17:
   case DW_OP_reg18:
   case DW_OP_reg19:
   case DW_OP_reg20:
   case DW_OP_reg21:
   case DW_OP_reg22:
   case DW_OP_reg23:
   case DW_OP_reg24:
   case DW_OP_reg25:
   case DW_OP_reg26:
   case DW_OP_reg27:
   case DW_OP_reg28:
   case DW_OP_reg29:
   case DW_OP_reg30:
   case DW_OP_reg31:
     reg = opcode - DW_OP_reg0;
     *(++sp) = registers.getRegister(reg);
     break;

   case DW_OP_regx:
     reg = addressSpace.getULEB128(p, expressionEnd);
     *(++sp) = registers.getRegister(reg);
     break;

   case DW_OP_breg0:
   case DW_OP_breg1:
   case DW_OP_breg2:
   case DW_OP_breg3:
   case DW_OP_breg4:
   case DW_OP_breg5:
   case DW_OP_breg6:
   case DW_OP_breg7:
   case DW_OP_breg8:
   case DW_OP_breg9:
   case DW_OP_breg10:
   case DW_OP_breg11:
   case DW_OP_breg12:
   case DW_OP_breg13:
   case DW_OP_breg14:
   case DW_OP_breg15:
   case DW_OP_breg16:
   case DW_OP_breg17:
   case DW_OP_breg18:
   case DW_OP_breg19:
   case DW_OP_breg20:
   case DW_OP_breg21:
   case DW_OP_breg22:
   case DW_OP_breg23:
   case DW_OP_breg24:
   case DW_OP_breg25:
   case DW_OP_breg26:
   case DW_OP_breg27:
   case DW_OP_breg28:
   case DW_OP_breg29:
   case DW_OP_breg30:
   case DW_OP_breg31:
     reg = opcode - DW_OP_breg0;
     svalue = addressSpace.getSLEB128(p, expressionEnd);
     *(++sp) = registers.getRegister(reg) + svalue;
     break;

   case DW_OP_bregx:
     reg = addressSpace.getULEB128(p, expressionEnd);
     svalue = addressSpace.getSLEB128(p, expressionEnd);
     *(++sp) = registers.getRegister(reg) + svalue;
     break;

   case DW_OP_deref_size:
     // pop stack, dereference, push result
     value = *sp--;
     switch (addressSpace.get8(p++)) {
     case 1:
       value = addressSpace.get8(value);
       break;
     case 2:
       value = addressSpace.get16(value);
       break;
     case 4:
       value = addressSpace.get32(value);
       break;
     case 8:
       value = addressSpace.get64(value);
       break;
     default:
       assert(0 && "DW_OP_deref_size with bad size");
     }
     *(++sp) = value;
     break;

   case DW_OP_fbreg:
   case DW_OP_piece:
   case DW_OP_xderef_size:
   case DW_OP_nop:
   case DW_OP_push_object_addres:
   case DW_OP_call2:
   case DW_OP_call4:
   case DW_OP_call_ref:
   default:
     assert(0 && "dwarf opcode not implemented");
   }
 }
 return *sp;
}

} // namespace _Unwind

#endif // __DWARF_INSTRUCTIONS_HPP__

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