How do I set 64-bit alignment for gcc from the command line?

In the man page I only found 8, 16 and 32 bits开发者_如何学运维.

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Use the -falign-* options: -falign-functions, -falign-labels, -falign-jumps.

Or, on i386/x86_64, if it's the stack boundary you want to keep aligned, use -mpreferred-stack-boundary=6 (2^6 = 64).