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| author | Kartik Agaram <vc@akkartik.com> | 2020-03-21 21:22:20 -0700 |
|---|---|---|
| committer | Kartik Agaram <vc@akkartik.com> | 2020-03-21 22:43:43 -0700 |
| commit | 0ef7f1d2d6f76ca3111cdbc59d4ae0038f61c2aa (patch) | |
| tree | 3731aa414e0c81d38159731c2f96669e3f453b2a /mu_instructions | |
| parent | fa805850240423ed3aa079270da26839a68c763e (diff) | |
| download | mu-0ef7f1d2d6f76ca3111cdbc59d4ae0038f61c2aa.tar.gz | |
6160 - plan for safe heap access
Based on apps/handle.subx (commit 4894), but we're able to simplify it further now that we know more about the situation we find ourselves in. 6 instructions, zero pushes or pops. Before I can start building this, I need to reorganize my use of handles. They're going to be fat pointers so we can't store them in registers anymore.
Diffstat (limited to 'mu_instructions')
| -rw-r--r-- | mu_instructions | 33 |
1 files changed, 31 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 |