Where are the Predefined Macros defined?

[bx L]

Hello everyone,
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.
Any ideas? Thanks.

[Andreas Schwab]

Post by bx L
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.

[bx L]

Cool, thanks!

Post by Andreas Schwab

Post by bx L
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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