I am trying to optimize a lot of multiplications and pointer arithmetics and would like to see what the compiler does underneath when I put in optimization flags.
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How to restrict it to a specific function or a code block?
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How to let gcc generate a less verbose assembly-code?
Add -S switch to your command line.
Edit: Do not forget that it will place the assembly to the files you specified under -o switch.
How to restrict it to a specific function or a code block?
Put that function in a separate source file (and use a different command-line parameter for that one source file).
You could also run that program in a debugger like gdb and use a disassembly view. In gdb you could use the command disass/m to view the assembly mixed with the C code on the current location.
You could stop you program at a breakpoint in the Visual Studio debugger and do "show assembly" and even step through it one instruction at a time.
来源：https://stackoverflow.com/questions/1354899/how-can-i-see-the-assembly-code-that-is-generated-by-a-gcc-any-flavor-compiler