All conditional statements ignored in `@ti.func` called from `@ti.real_func`

[Sam-Izdat]

Describe the bug
All conditional statements are ignored in any @ti.func called from any @ti.real_func. Code is executed as though all conditions evaluate to True. This happens on both Linux and Windows, both on gpu and cpu backends.

To Reproduce

A minimal reproducer:

import taichi as ti

ti.init(arch=ti.cpu)

@ti.func
def f_test() -> float:
	foo = 0.
	if False: foo = 1.
	return foo

@ti.real_func
def rf_test() -> float:
	return f_test()


@ti.kernel
def kern_test() -> float:
	return rf_test()

print(kern_test()) # Prints 1.0

Log/Screenshots

$ python my_sample_code.py
[Taichi] version 1.7.0, llvm 15.0.4, commit 2fd24490, linux, python 3.8.13
[Taichi] Starting on arch=x64
...

[Taichi] version 1.7.0, llvm 15.0.1, commit 2fd24490, win, python 3.8.17
[Taichi] Starting on arch=cuda
...

Additional comments
I assume this is a bug, unless I've badly misunderstood what is and is not UB. I still feel like I'm somehow responsible for this, but I haven't found anything to indicate that what I'm doing is forbidden. The code in this example calls func from real_func:

https://github.com/taichi-dev/taichi/blob/master/python/taichi/examples/real_func/graph/stable_fluid_graph.py

[Sam-Izdat]

Interestingly, ternary operators behave as expected:

@ti.func
def f_test1() -> float:
	foo = 1. if False else 0.
	return foo # returns 0.

@ti.func
def f_test2() -> float:
	foo = 1. if True else 0.
	return foo # returns 1.

[PDE26jjk]

Similar situation:
When calling @ti.func inside @ti.real_func, and @ti.func contains conditional statements, the program crashes immediately. The version is 1.7.4.

import taichi as ti

ti.init(arch=ti.cpu)
@ti.func
def f_test() -> float:
    foo = 0.
    if foo > 0.0: # crash
        foo += 1.0 
    return foo


@ti.real_func
def rf_test() -> float:
    return f_test()


@ti.kernel
def kern_test() -> float:
    return rf_test()


print(kern_test())