Hi Duncan,
Duncan Sands wrote:
Hi,
I'm using the ppc-linux gcc-4.2.2 compiler and noted the code
size have increased significantly (about 40%!), comparing with
old 4.0.0 when using the -Os option. Same code, same compile-
and configuration-time options. Binutils are differ
(2.16.1 vs 2.17.50), though.
what LLVM version is old 4.0.0? Are you compiling C++ (I don't know
what CSiBE is)? Are you using exception handling?
LLVM? From what I know llvm-gcc is an alternative for gcc. Are any
parts of LLVM used in current GCC? None of what I know.
CSiBE is the Code-Size Benchmark Environment, see
http://www.inf.u-szeged.hu/csibe
I've looked at the CSiBE testing results for ppc-elf with -Os,
comparing gcc_4_0_0 with mainline and found that the mainline
actually optimizes better, at least for the CSiBE test environment.
After some analysis I've came to the following results:
Number of packages in the CSiBE test environment: 863
N of packages where mainline GCC optimizes better: 290
N of packages where mainline GCC optimizes worse: 436
From these numbers it looks like llvm-gcc is better than mainline
most of the time. However you say: "... found that the mainline
actually optimizes better". Can you please clarify.
No, all results are for the GCC project. "Mainline" here means the
current development version of GCC. For it, the sum of the test code
size is 3503061, vs. 3542052 for the gcc_4_0_0 branch. But again,
this performance is achieved by the significant regression for the
most of the test packages.
Regards,
Sergei
Best wishes,
Duncan.
