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costa-group / gasol-optimizer

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Two MSTORE8 can lead to a type error #22

Closed RicoloveFeng closed 2 years ago

RicoloveFeng commented 2 years ago

I'm using the 2.0 release so I'm not sure whether it was fixed in a dev branch.

To reproduce, simply change the MSTORE this example:

SWAP1 PUSH1 0 MSTORE PUSH1 32 MSTORE

to MSTORE8:

SWAP1 PUSH1 0 MSTORE8 PUSH1 32 MSTORE8

Then you will get:

...
  File ".../gasol-optimizer-0.2.0/sfs_generator/gasol_optimization.py", line 4862, in are_dependent
    if ins1.find("mstore8")!=-1 and var1>=var2 and var1<var2+32:
TypeError: can only concatenate str (not "int") to str
...

The problem is that in gasol-optimizer-0.2.0/sfs_generator/gasol_optimization.py, the function are_dependent(var1,var2,ins1,ins2) expect that var1 and var2 are int, but somehow they are actually str.

alexcere commented 2 years ago

Hi RicoloveFeng,

Thanks for reporting the bug! The current dev branch basically consists of an improvement in the Max-SMT encoding, so both the latest release and the dev branch contain this bug. We were not aware of it before.

The fix is easy: in case var1 and var2 are not stack variables (i.e. they do not start with "s..."), and one of the instructions is MSTORE8, these variables must be cast to int. It seems we failed to notice this bug due to not appearing in any of our tests/experiments.

However, it also reveals some unexpected behavior when removing redundant combinations of MSTORE8, so we need to look thoroughly into the issue. We will let you know as soon as the full fix is ready.

tutugordillo commented 2 years ago

PUSH1 0 MSTORE8 MSTORE8 PUSH1 0 MSTORE8