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Using the GNU Compiler Collection (GCC)

Footnotes

(1)

loop discovery refers to the process by which a compiler, or indeed any reader of a program, determines which portions of the program are more likely to be executed repeatedly as it is being run. Such discovery typically is done early when compiling using optimization techniques, so the "discovered" loops get more attention--and more run-time resources, such as registers--from the compiler. It is easy to "discover" loops that are constructed out of looping constructs in the language (such as Fortran's DO). For some programs, "discovering" loops constructed out of lower-level constructs (such as IF and GOTO) can lead to generation of more optimal code than otherwise.

(2)

Future versions of GCC may zero-extend, or use a target-defined ptr_extend pattern. Do not rely on sign extension.

(3)

The analogous feature in Fortran is called an assigned goto, but that name seems inappropriate in C, where one can do more than simply store label addresses in label variables.

(4)

A file's basename was the name stripped of all leading path information and of trailing suffixes, such as `.h' or `.C' or `.cc'.