Ignorance of exception "integer divide by zero" in llvm-jit mode

[unicornt]

Test Case

report7.zip

Result

If I run this code on llvm-jit mode, it will exit normally. But in fast-jit mode or interp mode, it will threw an integer divide by zero exception.
By the way, I tried the same code with other runtimes. They all throw integer divide by zero exception.

Extra Information

If I change i32.div_s (in line 79) into i32.add, all runtimes will exit normally.
Maybe it is a problem of i32.rotl instruction because its result is different between llvm-jit mode and fast-jit mode.

Versions and Environment

wamr version : 1.2.3

Operating system: Ubuntu 20.04

Architecture: x86_64

[lum1n0us]

Because of the drop at L80, llvm-jit optimizer treats above Wasm instrctions as a kind of dead code and removes them in generation.

[unicornt]

Thank you for the explanation! Please let me know when and how you fix it.

[wenyongh]

Hi, I checked the issue again, it seems that it is caused by the i32.rotl opcode but not the i32.div_s opcode. It runs OK after applying patch #2697. For opcode i32.div_s, the AOT compiler adds checks and generates call IR to call aot_set_exception_with_id function, normally it should not be eliminated as dead code.

For example, for the wasm function below:

(func (export "test") (param i32)
   (i32.const 1234)
   (local.get 0)
   i32.div_s
   drop
)

The drop is added after i32.div_s, but after running iwasm -f test test.aot 0, the exception integer divide by zero was thrown.

[unicornt]

Hi, I checked the issue again, it seems that it is caused by the i32.rotl opcode but not the i32.div_s opcode. It runs OK after applying patch #2697. For opcode i32.div_s, the AOT compiler adds checks and generates call IR to call aot_set_exception_with_id function, normally it should not be eliminated as dead code.

For example, for the wasm function below:

(func (export "test") (param i32)
   (i32.const 1234)
   (local.get 0)
   i32.div_s
   drop
)

The drop is added after i32.div_s, but after running iwasm -f test test.aot 0, the exception integer divide by zero was thrown.

Yes, I tried it with patch #2697 and it can throw exception correctly. Thank you for the explanation about i32.div_s opcode!