== Quote from Walter Bright (newshou...@digitalmars.com)'s article > retard wrote: > > Mon, 31 May 2010 18:23:18 +0200, Pelle wrote: > > > >> On 05/31/2010 05:43 PM, retard wrote: > >>> DMD is much slower than Sun Javac/Jvm 7, GNU GCC 4.5, and LLVM. > >> For very special values of much, I suppose. > > > > Polymorphic method calls, auto-vectorization, link-time optimization, > > floating point performance, etc. > Link time optimization? Let's examine it: > https://lwn.net/Articles/387122/ > "When source files are compiled and linked using -flto, GCC applies > optimizations as if all the source code were in a single file. This allows GCC > to perform more aggressive optimizations across files, such as inlining the > body > of a function from one file that is called from a different file, and > propagating constants across files. In general, the LTO framework enables all > the usual optimizations that work at a higher level than a single function to > also work across files that are independently compiled." > D has had that for 8 years now, it's just done in the compiler instead of the > linker. You can specify as many D source modules as you want on the command > line > to the compiler, and it will compile & optimizer & inline them all together > and > generate one object file. > Essentially, link time optimization is a hack to get around the language > problem > C/C++ have with their separate compilation model. > To say D code is slower because it lacks link-time optimization is a false > supposition.
I was not aware that specifying multiple files at the same time affects optimization. This feature needs to be better integrated into IDEs. For small but computationally intensive scientific computing programs, I would rather ditch separate compilation entirely and just compile the entire program in one go. Nonetheless, CodeBlocks compiles each file separately by default, and if this is customizable I don't how how.
