How to get gcc to produce 64 bit code? m64 option produces "sorry" message!!

This is a discussion on How to get gcc to produce 64 bit code? m64 option produces "sorry" message!! within the C Programming forums, part of the General Programming Boards category; Hello programmers, I have a question about the options of gcc. I have a 64 bit processor with a fedora ...

  1. #1
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    How to get gcc to produce 64 bit code? m64 option produces "sorry" message!!

    Hello programmers,

    I have a question about the options of gcc. I have a 64 bit processor with a fedora 64 bit running on it. Both int and long are 32 bit long and long long is 64. when I use the -m64 option that I found info about somewhere online, the gcc responds with: sorry, unimplemented: 64 bit mode not compiled in.

    What can I do to fix that?

    Thank you,

  2. #2
    spurious conceit MK27's Avatar
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    If you are running FC-64, gcc is producing 64-bit code, you don't need to use a switch.

    Int is still a 4 byte value. "64-bit" refers to the memory addressing. So the difference is in the sizeof() pointers. If you check, all your pointers are 8 bytes long, to hold a 64-bit address. 32-bit pointers are 4 bytes.
    C programming resources:
    GNU C Function and Macro Index -- glibc reference manual
    The C Book -- nice online learner guide
    Current ISO draft standard
    CCAN -- new CPAN like open source library repository
    3 (different) GNU debugger tutorials: #1 -- #2 -- #3
    cpwiki -- our wiki on sourceforge

  3. #3
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    So I understand that gcc defines int to be 4 byte long on both 32 and 64 bit machines?

    Thanks

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