[LLVMbugs] [Bug 705] bizarre llvm-gcc behaviour (followup of llvm-g++ bug)

bugzilla-daemon at cs.uiuc.edu bugzilla-daemon at cs.uiuc.edu
Tue Feb 7 08:12:30 PST 2006


sabre at nondot.org changed:

           What    |Removed                     |Added
             Status|NEW                         |RESOLVED
         Resolution|                            |INVALID

------- Additional Comments From sabre at nondot.org  2006-02-07 10:12 -------
There are three reasons that it is far more costly to use llvm-g++ like that than G++:

1. LLVM is statically linking libstdc++ into your program, g++ is not (if you're using g++-4.0 on OS/X).
2. LLVM is interprocedurally optimizing the resultant program, which is several orders of magnitude 
more expensive than what GCC is doing.
3. You're almost certainly using a debug build, which is about 10x slower than a release build, as 
Andrew says.

For #3, when you build LLVM (not llvm-gcc), make sure to use 'make ENABLE_OPTIMIZED=1', then make 
sure that the llvm/Release/bin directory is in you path, not the llvm/Debug/bin directory.

If you don't that me closing this bug is reasonable, please reopen it.


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