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cgccassemblycodeblocksmingw-w64

How to view assembly code in codeblocks?

I want to see the assembly version of my C code and I've learned that -S option can show it but I get this error when using that option:

cannot specify -o with -c, -S or -E with multiple files

The only compiler options I have used besides that one are: -m64 and -Wfatal-errors. I use the Codebloc::Blocks IDE and mingw64 compiler. The source file is a43.c and I inserted the option in this place:

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Am I doing it right? I prefer using the GUI instead of command line.

Solution

  • The compiler options:

    -c  # compile only (don't link)
-S  # assemble only (don't compile or link)
-E  # preprocess only (don't assemble, compile or link)

    are mutually exclusive. Furthermore, you cannot specify:

    -o foo.o    # write output to `foo.o`

    if you are specifying multiple input source files.

    You are adding -S a43.c to the Other compiler options. That means you are adding them to the existing compilation options for your project. Those options already include -c by default, because that's the option to compile, so adding -S conflicts with -c.

    -S does not take any argument, specifically no filename argument. It tells gcc only to assemble (not compile or link) the input files, whatever they are. So adding:

    -S a43.c

    as well as adding -S to the existing options, adds an input file, a43.c, to the project's compiler options. But of course Code::Blocks will add the name of an input file to the compiler options whenever it compiles one of the files in the project. So there will be two source filenames in the commandline. Hence the error:

    cannot specify -o with -c, -S or -E with multiple files

    If you want to modify your Code::Blocks compilation options so that they will also produce the assembly listing of each file compiled, then remove

    -S a43.c

    from Other compiler options and replace it with

    -save-temps

    Then, whenever gcc compiles a file foo.c in the project, it will save the intermediate files as:

    foo.s   # The assembly
foo.i   # The preprocessed source

    These files will be saved in the same directory as foo.c itself; not in the directory where the object file foo.o is output.

    See the documentation of -save-temps in the GCC manual