lab/gprof

Gprof test program

• Needs gprof-enabled CeGCC.
• make to compile AppMain.exe.

CFLAGS

By default, GCC emits code that is not comformant to APCS. Gprof's _mcount assumes APCS-compliant and fp being present in the binary.

• -mapcs-frame is disabled by default for all optimization level
  • It leads to a crash without APCS. Must be enabled explicitly.
• -fno-omit-frame-pointer is enabled for all optimization level but -O0
  • It might have some effect on the compilation, but not sure
  • As I experiment unsetting (disabling) this flag, it doesn't crash even with -O2

Experiment results: flags' effect

• -fno-omit-frame-pointer looks like it has nothing to do with calling convention because of -mapcs-frame
• Optimization other than -O0 optimizes the func call (inlining etc) and the resulting graph becomes strange (lack of main() etc.)

CFLAGS	Screenshot
-O0
-O2