Disassemble the .lib file compiled with gcc-arm-8.3-2019.03-x86_64-arm-eabi compilation tool chain, and found that malloc is optimized to calloc.

[魏亚茹]

Dear gcc:
I find that disassemble the .lib file compiled with 
gcc-arm-8.3-2019.03-x86_64-arm-eabi compilation tool chain, and found that 
malloc is optimized to calloc. I want to know under what circumstances malloc 
will be optimized to calloc?
Thanks