Signed Register Functions
afrocheese opened this issue · comments
git clone --depth=50 https://github.com/lunixbochs/usercorn.git usercorn
cd usercorn
git fetch origin +refs/pull/311/merge
git checkout -f FETCH_HEAD
make deps
make
$ ./usercorn run -repl bins/x86_64.darwin.macho
0x100002426> rax = -1
0x100002426> rax
0xffffffffffffffff
0x100002426> rax = 0xffffffffffffffff
could not restore rax: bad type: NaN
This occurs on all architectures that I have tested and also occurs using u.reg_write.
I added int64 types to luaish but the parser probably needs to be modified to autopromote large constants.
Oh! parseNumber just needs to try parsing unsigned as well to handle the > int64 <= uint64 range
Fixed in lunixbochs/luaish@50b0cd6:
~/projects/luaish] ./glua
GopherLua 0.1 Copyright (C) 2015 Yusuke Inuzuka
> rax = 0.1
> print(rax)
0.1
> rax = 0xfffffffffffffff
> print(rax)
1152921504606846975
> rax = 0xffffffffffffffff
> print(rax)
-1
> rax = 0xfffffffffffffffff
> print(rax)
NaN
Run make get to update the luaish dependency.
Thanks for the quick turn around! The only slightly surprising behavior that I've noticed is writing a NaN number with u.reg_write, but I think it might be unrelated.
0x0> x0
0
0x0> u.reg_write(arm64.x0, 0xfffffffffffffffff)
0x0> x0
0x8000000000000000
Huh, what happens if you set a register to like 1.5? Maybe floats shouldn’t be allowed there.
0x0> x0 = 1.5
could not restore x0: bad type: 1.5
0x0> u.reg_write(arm64.x0, 1.999999)
0x0> x0
1
0x0> u.reg_write(arm64.x0, -0.999999)
0x0> x0
0
0x0> u.reg_write(arm64.x0, -1.999999)
0x0> x0
0xffffffffffffffff
0x0> u.reg_write(arm64.x0, -5.999999)
0x0> x0
0xfffffffffffffffb
seems to more or less make sense how it handles floats