Depending on the target and how GCC was configured, a slightly different set of optimizations may be enabled at each -O level than those listed here. You can invoke GCC with -Q --help=optimizers to find out the exact set of optimizations that are enabled at each level.

Here is a summary of all the options, grouped by type. Explanations are in the following sections. See Options Controlling the Kind of Output. See Options Controlling C Dialect. See Options Controlling C++ Dialect. See Options Controlling Objective-C and Objective-C++ Dialects. See Options Controlling OpenMP and OpenACC.

2022年4月5日 · -O3 optimizes for speed, whereas -Os optimizes for space. That means -O3 will give you a fast executable, but it may be rather large, and -Os gives you a smaller executable, but it might be slower. Space and time efficiency is usually a trade-off.

If you only want some of the stages of compilation, you can use -x (or filename suffixes) to tell gcc where to start, and one of the options -c, -S, or -E to say where gcc is to stop. Note that some combinations (for example, ‘ -x cpp-output -E ’) instruct gcc to do nothing at all.

Like most GNU software, GCC must be configured before it can be built. This document describes the recommended configuration procedure for both native and cross targets. We use srcdir to refer to the toplevel source directory for GCC; we use objdir to …

To be pedantic, there are 8 different valid -O options you can give to gcc, though there are some that mean the same thing. The original version of this answer stated there were 7 options. GCC has since added -Og to bring the total to 8. From the man page:

The GNU Compiler Collection (GCC) is a toolkit for compiling and assembling programs for a wide variety of platforms and languages. It is one of the core utilities in the Free Software Foundation's GNU Project.

2011年5月12日 · Seems odd to me that 90% of this "map" is user-space programs. Why is cp or mkdir considered part of the GNU/Linux OS internals?

The GNU Compiler Collection (GCC) is a collection of compilers from the GNU Project that support various programming languages, hardware architectures and operating systems. The Free Software Foundation (FSF) distributes GCC as free software under the GNU General Public License (GNU GPL).

2017年2月2日 · You could either type exactly /usr/bin/gcc, or add some alias to your interactive shell configuration (often ~/.bashrc which you might edit with great care), or change your PATH setting, or, assuming which gcc gives something like /home/zaid/bin/gcc (i.e. your $HOME/bin/gcc if $HOME/bin appears early in your $PATH), add a symbolic link ln -sv ...