steve
/
factor
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

VM: simplifies the dispatch_resumable_signal() method

db4
Björn Lindqvist 2015-08-15 00:08:42 +02:00 committed by John Benediktsson
parent b8aef640f9
commit 1b1b275a1a
1 changed files with 13 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

29
vm/cpu-x86.cpp
View File

@ -13,8 +13,9 @@ void factor_vm::dispatch_non_resumable_signal(cell* sp, cell* pc,
signal_resumable = false;
cell frame_top = ctx->callstack_top;
cell seg_start = ctx->callstack_seg->start;
if (frame_top < ctx->callstack_seg->start) {
if (frame_top < seg_start) {
/* The saved callstack pointer is outside the callstack
segment. That means that we need to carefully cut off one frame
first which hopefully should put the pointer within the
@ -28,7 +29,7 @@ void factor_vm::dispatch_non_resumable_signal(cell* sp, cell* pc,
frame that leaves room for the signal handler to do its thing,
and launch the handler without going through the resumable
subprimitive. */
FACTOR_ASSERT(ctx->callstack_seg->start <= frame_top);
FACTOR_ASSERT(seg_start <= frame_top);
while (frame_top < ctx->callstack_bottom && frame_top < limit) {
frame_top = code->frame_predecessor(frame_top);
}
@ -56,27 +57,23 @@ void factor_vm::dispatch_resumable_signal(cell* sp, cell* pc, cell handler) {
leafness by matching the PC to a word. We should also use
FRAME_RETURN_ADDRESS instead of assuming the stack pointer is the
right place to put the resume address. */
cell word_idx = 0;
cell index = 0;
cell delta = 0;
if (offset == 0) {
word_idx = SIGNAL_HANDLER_WORD;
cell newsp = *sp - sizeof(cell);
*sp = newsp;
*(cell*)newsp = *pc;
delta = sizeof(cell);
index = SIGNAL_HANDLER_WORD;
} else if (offset == 16 - sizeof(cell)) {
word_idx = LEAF_SIGNAL_HANDLER_WORD;
/* Make a fake frame for the leaf procedure */
FACTOR_ASSERT(code->code_block_for_address(*pc) != NULL);
cell newsp = *sp - LEAF_FRAME_SIZE;
*sp = newsp;
*(cell*)newsp = *pc;
delta = LEAF_FRAME_SIZE;
index = LEAF_SIGNAL_HANDLER_WORD;
} else {
FACTOR_ASSERT(false);
}
tagged<word> handler_word = tagged<word>(special_objects[word_idx]);
cell new_sp = *sp - delta;
*sp = new_sp;
*(cell*)new_sp = *pc;
tagged<word> handler_word = tagged<word>(special_objects[index]);
*pc = (cell)handler_word->entry_point;
}