How to disable compiler optimizations in gcc?

c gcc compiler-optimization compiler-options
Neal picture Neal · Apr 23, 2011 · Viewed 105.9k times · Source

I am trying to learn assembly language. I have searched and found how to disassemble a .c file but I think it produces some optimized version of the program. Is there any way so that I can see the exact assembly code which corresponds to my C file.

Answer

pmr picture pmr · Apr 23, 2011

The gcc option -O enables different levels of optimization. Use -O0 to disable them and use -S to output assembly. -O3 is the highest level of optimization.

Starting with gcc 4.8 the optimization level -Og is available. It enables optimizations that do not interfere with debugging and is the recommended default for the standard edit-compile-debug cycle.

To change the dialect of the assembly to either intel or att use -masm=intel or -masm=att.

You can also enable certain optimizations manually with -fname.

Have a look at the gcc manual for much more.

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