The current fact is that C1 uses more stack space than the C2 compiler, taking method `java.lang.Object::<init>`as an example on the x86_64 platform , the stack size used is 48 bytes for C1 compiler, while only 16 bytes is used for C2 compiler.

========== C1-compiled nmethod =====
0x00007f93311cc747: push %rbp
0x00007f93311cc748: sub $0x30,%rsp // stack sizes is 48 bytes


========== C2-compiled nmethod =======
    pushq rbp # Save rbp
    subq rsp, #16 # Create frame //stack sizes is 16 bytes

Therefore, the stack space of C1 compiler has great optimization possibilities.