When should I use GCC's -pipe option?

user_33732 0
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The GCC 4.1.2 documentation has this to say about the -pipe option:

-pipe

Use pipes rather than temporary files for communication between the various stages of compilation. This fails to work on some systems where the assembler is unable to read from a pipe; but the GNU assembler has no trouble.

I assume I'd be able to tell from error message if my systems' assemblers didn't support pipes, so besides that issue, when does it matter whether I use that option? What factors should go into deciding to use it?

compiler-options pipe gcc
6 Answers

In our experience with a medium-sized project, adding -pipe made no discernible difference in build times. We ran into a couple of problems with it (sometimes failing to delete intermediate files if an error was encountered, IIRC), and so since it wasn't gaining us anything, we quit using it rather than trying to troubleshoot those problems.

Josh_Kelley_255070

One advantage is that with -pipe will the compiler interact less with a file system. Even when it is a ram disk does the data still need to go through the block I/O and file system layers when using temporary files whereas with a pipe it becomes a bit more direct.

With files does the compiler first need to finish writing before it can call the assembler. Another advantage of pipes is that both, the compiler and assembler, can run at the same time and it is making a bit more use of SMP architectures. Especially when the compiler needs to wait for the data from the source file (because of blocking I/O calls) can the operating system give the assembler full CPU time and let it do its job faster.

user_12981210
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