I tried to config the 8051 project and found a problem after disassembler the code.
There are some library link in the code such as libsdcc.lib (startup.rel).

After reset the program call a few thing and then jump to 0x03 and then long jump to address 0x62.
which the start of (Main)
I have yet found clear ram or set stack pointer assembly code from startup.rel

By the way , the example code (dht11 sdcc toolchian) from remote repository found the same problem.

I insert hex code as here after.

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