NAME

src/gc/system.c - CPU-dependent mark/sweep functions

DESCRIPTION

These functions setup a trace of the current processor context and the system stack. The trace is set up here in trace_system_areas. This function gets the current processor context and either traces it directly or stores it on the system stack. trace_system_stack sets up a trace of the system stack using two marker addresses as boundaries. The code to actually perform the trace of a memory block between two boundaries is located in src/gc/api.c:trace_mem_block.

TT #273: This file needs to be cleaned up significantly.

Functions

void trace_system_areas

Initiates a trace of the system stack, looking for pointers which are being used by functions in the call chain, but which might not be marked as alive in any other way. Setting the trace up, which involves storing the processor context onto the stack, is highly system dependent. However, once stored, tracing the stack is very straightforward.

static void trace_system_stack

Traces the memory block starting at interp->lo_var_ptr. This should be the address of a local variable which has been created on the stack early in the interpreter's lifecycle. We trace until the address of another local stack variable in this function, which should be at the "top" of the stack.

static size_t find_common_mask

Finds a mask covering the longest common bit-prefix of val1 and val2.

void trace_mem_block

Traces the memory block between lo_var_ptr and hi_var_ptr. Attempt to find pointers to PObjs or buffers, and mark them as "alive" if found. See src/cpu_dep.c for more information about tracing memory areas.

SEE ALSO

src/gc/api.c and include/parrot/gc_api.h.