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| author | Kartik Agaram <vc@akkartik.com> | 2019-01-04 11:29:12 -0800 |
|---|---|---|
| committer | Kartik Agaram <vc@akkartik.com> | 2019-01-04 11:29:12 -0800 |
| commit | 7b548ff5c5792422f1cc05896adf2f63f5af41c7 (patch) | |
| tree | a040af0320e241dda29780b752c3b55f0ee3e853 /subx/apps | |
| parent | 8413cd9c9dec77a7bbd2b9eb468e003c2b2c1afd (diff) | |
| download | mu-7b548ff5c5792422f1cc05896adf2f63f5af41c7.tar.gz | |
4905 - safe ptr lookup is now 6 instructions
The lines within '{}' can now be turned into a macro like `E_X = deref(E_X)`,
parameterizing the register being modified.
Assumes the input is in a register but also saved elsewhere, so it's safe
to clobber and replace with the result.
Compare commit 4894. Used to take 9 instructions, 8 of them making loads/stores.
Now it's 6 instructions, 4 of them loads/stores (the one non-local load
is unchanged, of course). Key is to not consume more registers so we don't
have to push/pop them.
Diffstat (limited to 'subx/apps')
| -rwxr-xr-x | subx/apps/handle | bin | 7954 -> 7952 bytes | |||
| -rw-r--r-- | subx/apps/handle.subx | 45 |
2 files changed, 20 insertions, 25 deletions
diff --git a/subx/apps/handle b/subx/apps/handle index 61558084..7bc762e4 100755 --- a/subx/apps/handle +++ b/subx/apps/handle Binary files differdiff --git a/subx/apps/handle.subx b/subx/apps/handle.subx index 8a2b5d05..bf452cc1 100644 --- a/subx/apps/handle.subx +++ b/subx/apps/handle.subx @@ -201,21 +201,26 @@ lookup: # h : (handle T) -> EAX : (address T) # . prolog 55/push-EBP 89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP - # . save registers - 51/push-ECX - 52/push-EDX - # ECX = handle - 8b/copy 1/mod/*+disp8 5/rm32/EBP . . . 1/r32/ECX 8/disp8 . # copy *(EBP+8) to ECX - # EDX = handle->alloc_id - 8b/copy 0/mod/indirect 1/rm32/ECX . . . 2/r32/EDX . . # copy *ECX to EDX - # EAX = handle->address - 8b/copy 1/mod/*+disp8 1/rm32/ECX . . . 0/r32/EAX 4/disp8 . # copy *(ECX+4) to EAX - # if (*EAX == EDX) return - 39/compare 0/mod/indirect 0/rm32/EAX . . . 2/r32/EDX . . # compare *EAX and EDX - 74/jump-if-equal $lookup:success/disp8 - # otherwise print a message and exit - # hard-coded abort just to minimize args and simplify calls - # TODO: emit stack trace, etc. + # - as a proof of concept for future inlining, uses no general-purpose registers besides the output (EAX) + # EAX = handle + 8b/copy 1/mod/*+disp8 5/rm32/EBP . . . 0/r32/EAX 8/disp8 . # copy *(EBP+8) to EAX + # - inline { + # push handle->address + ff 6/subop/push 1/mod/*+disp8 1/rm32/ECX . . . . 4/disp8 . # push *(EAX+4) + # EAX = handle->alloc_id + 8b/copy 0/mod/indirect 0/rm32/EAX . . . . . . # copy *EAX to EAX + # if (EAX != *ESP) abort + 39/compare 0/mod/indirect 4/rm32/sib 4/base/ESP 4/index/none . 0/r32/EAX . . # compare *ESP and EAX + 75/jump-if-not-equal $lookup:fail/disp8 + # return ESP+4 + 58/pop-to-EAX + 05/add-to-EAX 4/imm32 + # - } + # . epilog + 89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP + 5d/pop-to-EBP + c3/return +$lookup:fail: # . _write(2/stderr, msg) # . . push args 68/push "lookup failed"/imm32 @@ -228,16 +233,6 @@ lookup: # h : (handle T) -> EAX : (address T) bb/copy-to-EBX 1/imm32/exit-status b8/copy-to-EAX 1/imm32/exit cd/syscall 0x80/imm8 -$lookup:success: - # increment past payload alloc id - 05/add-to-EAX 4/imm32 - # . restore registers - 5a/pop-to-EDX - 59/pop-to-ECX - # . epilog - 89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP - 5d/pop-to-EBP - c3/return test-lookup-success: # . prolog |