[LLVMdev] llvm-gcc -O0 compile times

Duncan Sands baldrick at free.fr
Sun Jun 22 00:46:14 PDT 2008

Hi Chris,

> I've started investigating -O0 -g compile times with llvm-gcc, which  
> are pretty important for people in development mode (e.g. all debug  
> builds of llvm itself!).

even without -g the -O0 performance is not great.  I compared the time
for llvm-gcc to compile to bitcode (-emit-llvm) against the time for
mainline gcc-4.2 to compile to assembler.  llvm-gcc was about 15% slower
even though it didn't have to do codegen.  Removing all names "tmp" (as
recently committed on mainline) speed up llvm-gcc enough that it was taking
the same time as mainline.  This is still without llvm-gcc doing codegen;
adding codegen in is sure to slow things down noticeably...



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