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Re: Inexpensive ARM compilers
Paul,

you got it to the point (the libs) where the weakest point of GNU is.
The standard library generates slightly humongus code.

AFAIK, the Keil version you used is actually a GNU C-Compiler with the
Standard LIB, embedded in the Keil uVision.  There is a new compiler,
non-GNU which generates much better code and has its own libraries.

As a compiler, not looking at the libraries, numbers that I have seen
compiling some benchmarks ourselves were in the range 20-30 larger than
best in class (was ARM about 18 months ago). Nevertheless, using the
GNU Libs, it was more than a factor of 2.

Summary: the secret is mostly in the libraries

Robertus


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Re: Inexpensive ARM compilers

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Hmm, Ulf references -30% on the kernel, and I think the kernel doesn't
utilize the "C standard library" much compared to a user app, so the
gain might be in "core" code optimization.

In fairness to this thread, I should have stated that "my informal
comparisons" used compilers for other (i.e., non-ARM) RISC
architectures (e.g., PowerPC, i960, and 29000) and are now dated.  For
example MetaWare's PPC compiler *was* pretty good compared to GCC's
code generation.  Is it still?  I don't know.

If GCC has reeled in some of the gap, I'm happy because the last two
and the current projects are at the Linux bootloader/kernel/driver
level with me still using GCC.

--
Dan Henry

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