RTL: fix an issue with abs()

[certik]

Previously the abs() was somehow returning a negative number, because we called it with an int8_t argument, but it was expecting "int" argument.

The other bug was that "num" in the for loop stayed at -1 forever. We fixed that by using the condition "num > 0". We also switched to a while loop which make it more readable.

Fixes #1825.

[Smit-create]

Thanks, It's clean!

[ubaidsk]

Team, does this actually fix #1825?

On latest main, compiling using the following commands

./build0.sh
cmake -DWITH_FMT=yes -DCMAKE_CXX_FLAGS_RELEASE="-Wall -Wextra -O3 -funroll-loops -DNDEBUG" -DWITH_LLVM=yes .
cmake --build . -j16

I am experiencing the following:

$ python integration_tests/test_bit_length.py               
7
3
7
7
$ lpython integration_tests/test_bit_length.py               
AssertionError

[ubaidsk]

In #1835 (comment), am I using the correct/expected flags for release mode compilation?

Also,

$ cat integration_tests/test_bit_length.py 
from math import floor, log2
from lpython import i8, i32, i16

def ff3():
    x: i16
    one: i16
    one = i16(1)
    x = -i16(one << i16(13))
    print("ff3(): x.bit_length() =", x.bit_length(), ", where x is", x)
    assert i32(x.bit_length()) == 14

ff3()
$ python integration_tests/test_bit_length.py 
ff3(): x.bit_length() = 14 , where x is -8192
$ lpython integration_tests/test_bit_length.py
ff3(): x.bit_length() = 0 , where x is -8192
AssertionError

[certik]

@Shaikh-Ubaid can you open up a new issue? It looks like you are getting a failure:

$ lpython integration_tests/test_bit_length.py               
AssertionError

But it works on my laptop as well as the CI. Let's try to reproduce the problem that you are seeing and then we'll fix it.

[ubaidsk]

@Shaikh-Ubaid can you open up a new issue? It looks like you are getting a failure:But it works on my laptop as well as the CI. Let's try to reproduce the problem that you are seeing and then we'll fix it.

Sure. Opened here #1836.