factor/vm/code_blocks.hpp

115 lines
3.2 KiB
C++

namespace factor {
// The compiled code heap is structured into blocks.
struct code_block {
// header format (bits indexed with least significant as zero):
// bit 0 : free?
// bits 1-2: type (as a code_block_type)
// if not free:
// bits 3-23: code size / 8
// bits 24-31: stack frame size / 16
// if free:
// bits 3-end: code size / 8
cell header;
cell owner; // tagged pointer to word, quotation or f
cell parameters; // tagged pointer to array or f
cell relocation; // tagged pointer to byte-array or f
bool free_p() const { return (header & 1) == 1; }
code_block_type type() const {
return (code_block_type)((header >> 1) & 0x3);
}
void set_type(code_block_type type) {
header = ((header & ~0x7) | (type << 1));
}
bool pic_p() const { return type() == CODE_BLOCK_PIC; }
cell size() const {
cell size;
if (free_p())
size = header & ~7;
else
size = header & 0xFFFFF8;
FACTOR_ASSERT(size > 0);
return size;
}
cell stack_frame_size() const {
if (free_p())
return 0;
return (header >> 20) & 0xFF0;
}
cell stack_frame_size_for_address(cell addr) const {
cell natural_frame_size = stack_frame_size();
// The first instruction in a code block is the prolog safepoint,
// and a leaf procedure code block will record a frame size of zero.
// If we're seeing a stack frame in either of these cases, it's a
// fake "leaf frame" set up by the signal handler.
if (natural_frame_size == 0 || addr == entry_point())
return LEAF_FRAME_SIZE;
return natural_frame_size;
}
void set_stack_frame_size(cell frame_size) {
FACTOR_ASSERT(size() < 0xFFFFFF);
FACTOR_ASSERT(!free_p());
FACTOR_ASSERT(frame_size % 16 == 0);
FACTOR_ASSERT(frame_size <= 0xFF0);
header = (header & 0xFFFFFF) | (frame_size << 20);
}
template <typename Fixup> cell size(Fixup fixup) const { return size(); }
cell entry_point() const { return (cell)(this + 1); }
// GC info is stored at the end of the block
gc_info* block_gc_info() const {
return (gc_info*)((uint8_t*)this + size() - sizeof(gc_info));
}
void flush_icache() { factor::flush_icache((cell)this, size()); }
template <typename Iterator> void each_instruction_operand(Iterator& iter) {
if (!to_boolean(relocation))
return;
byte_array* rels = untag<byte_array>(relocation);
cell index = 0;
cell length = untag_fixnum(rels->capacity) / sizeof(relocation_entry);
for (cell i = 0; i < length; i++) {
relocation_entry rel = rels->data<relocation_entry>()[i];
iter(instruction_operand(rel, this, index));
index += rel.number_of_parameters();
}
}
cell offset(cell addr) const { return addr - entry_point(); }
cell address_for_offset(cell offset) const {
return entry_point() + offset;
}
cell scan(factor_vm* vm, cell addr) const;
cell owner_quot() const;
};
VM_C_API void undefined_symbol(void);
inline code_block* word::code() const {
FACTOR_ASSERT(entry_point != 0);
return (code_block*)entry_point - 1;
}
inline code_block* quotation::code() const {
FACTOR_ASSERT(entry_point != 0);
return (code_block*)entry_point - 1;
}
}