diff options
| -rw-r--r-- | mu_instructions | 33 | ||||
| -rw-r--r-- | mu_summary | 24 |
2 files changed, 55 insertions, 2 deletions
diff --git a/mu_instructions b/mu_instructions index 4c62d4bd..7b2d53b3 100644 --- a/mu_instructions +++ b/mu_instructions @@ -157,7 +157,7 @@ Address operations var/reg: (addr T) <- address var: T => "8d/copy-address *(ebp+" var.stack-offset ") " reg "/r32" -Array operations +Array operations (TODO: bounds-checking) var/reg <- length arr/reg2: (addr array T) => "8b/-> *" reg2 " " reg "/r32" @@ -187,4 +187,33 @@ var/reg: (addr T_f) <- get var2/reg2: (addr F), f var/reg: (addr T_f) <- get var2: (addr F), f => "8d/copy-address *(ebp+" var2.stack-offset "+" offset(f) ") " reg "/r32" -vim:ft=mu:nowrap:tw& +Handles for safe access to the heap + +copy-handle-to dest: (handle T), src: (handle T) + => "50/push-eax" + "8b/-> *(ebp+" src.stack-offset ") 0/r32/eax" + "89/<- *(ebp+" dest.stack-offset ") 0/r32/eax" + "8b/-> *(ebp+" src.stack-offset+4 ") 0/r32/eax" + "89/<- *(ebp+" dest.stack-offset+4 ") 0/r32/eax" + "58/pop-to-eax" + +copy-handle-to *dest/reg: (addr handle T), src: (handle T) + => "50/push-eax" + "8b/-> *(ebp+" src.stack-offset ") 0/r32/eax" + "89/<- *" reg " 0/r32/eax" + "8b/-> *(ebp+" src.stack-offset+4 ") 0/r32/eax" + "89/<- *(" reg "+4) 0/r32/eax" + "58/pop-to-eax" + +out/reg: (addr T) <- lookup in: (handle T) + => # payload_allocid = in->address->allocid + "8b/-> *(epb+" (in.stack-offset+4) ") " reg "/r32" + "8b/-> *" reg " " reg "/r32" + # if (payload_allocid != handle->allocid) abort + "39/compare *(ebp+" in.stack-offset ") " reg "/r32" + "0f 85/jump-if-!= $lookup:abort/disp32" + # return payload + "8b/-> *(epb+" (in.stack-offset+4) ") " reg "/r32" + "81 0/subop/add %" reg " 4/imm32" # skip payload->allocid + +vim:ft=mu:nowrap:textwidth=0 diff --git a/mu_summary b/mu_summary index d098d28f..1ac7a086 100644 --- a/mu_summary +++ b/mu_summary @@ -216,3 +216,27 @@ Similarly, conditional loops: var/reg: (addr T_f) <- get var/reg: (addr T), f where record (product) type T has elements a, b, c, ... of types T_a, T_b, T_c, ... var/reg: (addr T_f) <- get var: (addr T), f + +## Handles for safe access to the heap + +Say we created a handle like this on the stack (it can't be in a register) + var x: (handle T) + allocate Heap, T, x + +You can copy handles to another variable on the stack like this: + var y: (handle T) + copy-handle-to y, x + +You can also save handles inside other user-defined types like this: + var y/reg: (addr handle T_f) <- get var: (addr T), f + copy-handle-to *y, x + +Or this: + var y/reg: (addr handle T) <- index arr: (addr array handle T), n + copy-handle-to *y, x + +Handles can be converted into addresses like this: + var y/reg: (addr T) <- lookup x + +It's illegal to continue to use this addr after a function that reclaims heap +memory. You have to repeat the lookup. |