sysio::vm::machine_code_writer< Context >::br_table_generator Struct Reference

#include <x86_64.hpp>

Collaboration diagram for sysio::vm::machine_code_writer< Context >::br_table_generator:

Classes
struct	stack_item

Public Member Functions
void *	emit_case (uint32_t depth_change)
void *	emit_default (uint32_t depth_change)
void *	emit_case (uint32_t depth_change)
void *	emit_default (uint32_t depth_change)

Public Attributes
machine_code_writer *	_this
int	_i = 0
std::vector< stack_item >	stack

Detailed Description

template<typename Context>
struct sysio::vm::machine_code_writer< Context >::br_table_generator

Definition at line 228 of file x86_64.hpp.

Member Function Documentation

emit_case() [1/2]

template<typename Context >

void * sysio::vm::machine_code_writer< Context >::br_table_generator::emit_case ( uint32_t depth_change )

inline

Definition at line 229 of file x86_64.hpp.

                                                {
            while(true) {
               assert(!stack.empty() && "The parser is supposed to handle the number of elements in br_table.");
               auto [min, max, label] = stack.back();
               stack.pop_back();
               if (label) {
                  fix_branch(label, _this->code);
               }
               if (max - min > 1) {
                  // Emit a comparison to the midpoint of the current range
                  uint32_t mid = min + (max - min)/2;
                  // cmp i, %mid
                  _this->emit_bytes(0x3d);
                  _this->emit_operand32(mid);
                  // jae MID
                  _this->emit_bytes(0x0f, 0x83);
                  void* mid_label = _this->emit_branch_target32();
                  stack.push_back({mid,max,mid_label});
                  stack.push_back({min,mid,nullptr});
               } else {
                  assert(min == static_cast<uint32_t>(_i));
                  _i++;
                  if (depth_change == 0u || depth_change == 0x80000001u) {
                     if(label) {
                        return label;
                     } else {
                        // jmp TARGET
                        _this->emit_bytes(0xe9);
                        return _this->emit_branch_target32();
                     }
                  } else {
                     // jne NEXT
                    _this->emit_multipop(depth_change);
                    // jmp TARGET
                    _this->emit_bytes(0xe9);
                    return _this->emit_branch_target32();
                  }
               }
            }
 
         }

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emit_case() [2/2]

template<typename Context >

void * sysio::vm::machine_code_writer< Context >::br_table_generator::emit_case ( uint32_t depth_change )

inline

Definition at line 229 of file x86_64.hpp.

                                                {
            while(true) {
               assert(!stack.empty() && "The parser is supposed to handle the number of elements in br_table.");
               auto [min, max, label] = stack.back();
               stack.pop_back();
               if (label) {
                  fix_branch(label, _this->code);
               }
               if (max - min > 1) {
                  // Emit a comparison to the midpoint of the current range
                  uint32_t mid = min + (max - min)/2;
                  // cmp i, %mid
                  _this->emit_bytes(0x3d);
                  _this->emit_operand32(mid);
                  // jae MID
                  _this->emit_bytes(0x0f, 0x83);
                  void* mid_label = _this->emit_branch_target32();
                  stack.push_back({mid,max,mid_label});
                  stack.push_back({min,mid,nullptr});
               } else {
                  assert(min == static_cast<uint32_t>(_i));
                  _i++;
                  if (depth_change == 0u || depth_change == 0x80000001u) {
                     if(label) {
                        return label;
                     } else {
                        // jmp TARGET
                        _this->emit_bytes(0xe9);
                        return _this->emit_branch_target32();
                     }
                  } else {
                     // jne NEXT
                    _this->emit_multipop(depth_change);
                    // jmp TARGET
                    _this->emit_bytes(0xe9);
                    return _this->emit_branch_target32();
                  }
               }
            }
 
         }

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emit_default() [1/2]

template<typename Context >

void * sysio::vm::machine_code_writer< Context >::br_table_generator::emit_default ( uint32_t depth_change )

inline

Definition at line 270 of file x86_64.hpp.

                                                   {
            void* result = emit_case(depth_change);
            assert(stack.empty() && "unexpected default.");
            return result;
         }

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emit_default() [2/2]

template<typename Context >

void * sysio::vm::machine_code_writer< Context >::br_table_generator::emit_default ( uint32_t depth_change )

inline

Definition at line 270 of file x86_64.hpp.

                                                   {
            void* result = emit_case(depth_change);
            assert(stack.empty() && "unexpected default.");
            return result;
         }

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Member Data Documentation

_i

template<typename Context >

int sysio::vm::machine_code_writer< Context >::br_table_generator::_i = 0

Definition at line 276 of file x86_64.hpp.

_this

template<typename Context >

machine_code_writer * sysio::vm::machine_code_writer< Context >::br_table_generator::_this

Definition at line 275 of file x86_64.hpp.

stack

template<typename Context >

std::vector< stack_item > sysio::vm::machine_code_writer< Context >::br_table_generator::stack

Definition at line 285 of file x86_64.hpp.

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The documentation for this struct was generated from the following files:

• libraries/sys-vm/include/sysio/sysio/vm/x86_64.hpp
• libraries/sys-vm/include/sysio/vm/x86_64.hpp