Where are the Predefined Macros defined?

[Andreas Schwab]

On Sep 29 2018, bx L <lbxlbxlbxlbxlbx@gmail.com> wrote:

>      I notice that gcc has some predefined macros, which can be
> obtained with " gcc -dM -E - < /dev/null". I guess many of them are
> machine-specified, such as __LDBL_MANT_DIG__. However, I can't find
> where these macros are defined when browsing GCC's source codes. I'm
> very curious about how these macros are defined.

Look for builtin_define, then inspect the context to see where the macro
names are constructed.  For example, c-family/c-cppbuiltin.c has a lot
of them.

Andreas.

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Andreas Schwab, schwab@linux-m68k.org
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