llvm dev - Apr 2008 - [LLVMdev] Getting debug information w/ optimizations

I am trying to build a bytecode file with optimizations and debug
information using llvm-gcc.  Compiling with "-g" works fine, but when
I add the optimizations flag, all debug information disappears.

On the other hand, if I first "-emit-llvm" with "-g" and no
optimizations, and then apply "opt -std-compile-opts", then debug
information seems to be preserved.

I have two questions:
1)  The "Source Level Debugging with LLVM" documentation page states
the following:  "Compiling a program with "-O3 -g" gives you full
debug information that is always available and accurate for reading
[...]"  Is this incorrect or am I missing something?  What is causing
the debug info to be wiped?
2)  Are the llvm-gcc -O levels (e.g. -O1, -O2, etc.) approximately
equivalent to the regular gcc -O levels, or are they really quite
different?  I couldn't find any recent discussion on this in the
archives.

Many thanks,
Marc

Hi, running llvm-gcc with optimization turns off debug info.  That
is because the LLVM optimizers do not yet know how to deal with it
well.
> 1)  The "Source Level Debugging with LLVM" documentation page
states
> the following:  "Compiling a program with "-O3 -g" gives you
full
> debug information that is always available and accurate for reading
> [...]"  Is this incorrect or am I missing something?  What is causing
> the debug info to be wiped?
It is not being generated in the first place.  The above quote reflects
a vision of the future and not present reality!
> 2)  Are the llvm-gcc -O levels (e.g. -O1, -O2, etc.) approximately
> equivalent to the regular gcc -O levels, or are they really quite
> different?  I couldn't find any recent discussion on this in the
> archives.
In my experience -O2 is about the same, while gcc's -O3 and llvm-gcc's
-O3 differ quite a lot.  Your mileage may vary :)

Ciao,

Duncan.