diff options
Diffstat (limited to 'mu_instructions')
| -rw-r--r-- | mu_instructions | 26 |
1 files changed, 25 insertions, 1 deletions
diff --git a/mu_instructions b/mu_instructions index 1037e8e3..754f51bb 100644 --- a/mu_instructions +++ b/mu_instructions @@ -183,11 +183,35 @@ var/reg: (offset T) <- compute-offset arr: (addr array T), idx: int # arr var/reg <- index arr/rega: (addr array T), o/rego: offset => "8d/copy-address *(" rega "+" rego "+4) " reg "/r32" -Computing the length of an array can get complex. +Computing the length of an array is complex. var/reg <- length arr/reg2: (addr array T) | if T is byte (TODO) => "8b/-> *" reg2 " " reg "/r32" + | if size-of(T) is 4 or 8 or 16 or 32 or 64 or 128 + => "8b/-> *" reg2 " " reg "/r32" + "c1/shift 5/subop/logic-right %" reg " " log2(size-of(T)) "/imm8" + | otherwise (TODO) + x86 has no instruction to divide by a literal, so + we need up to 3 extra registers! eax/edx for division and say ecx + => if reg is not eax + "50/push-eax" + if reg is not ecx + "51/push-ecx" + if reg is not edx + "52/push-edx" + "8b/-> *" reg2 " eax/r32" + "31/xor %edx 2/r32/edx" # sign-extend, but array size can't be negative + "b9/copy-to-ecx " size-of(T) "/imm32" + "f7 7/subop/idiv-eax-edx-by %ecx" + if reg is not eax + "89/<- %" reg " 0/r32/eax" + if reg is not edx + "5a/pop-to-edx" + if reg is not ecx + "59/pop-to-ecx" + if reg is not eax + "58/pop-to-eax" # User-defined types |