[cfe-commits] r166236 - in /cfe/trunk: include/clang/Driver/CC1Options.td include/clang/Driver/Options.td include/clang/Frontend/CodeGenOptions.h lib/CodeGen/CGDebugInfo.cpp lib/Driver/Tools.cpp lib/Frontend/CompilerInvocation.cpp test/CodeGen/debug-info-iv.c test/CodeGen/debug-info-line3.c test/CodeGen/debug-info-line4.c test/CodeGen/debug-line-1.c test/CodeGenCXX/debug-info-globalinit.cpp test/CodeGenCXX/destructor-debug-info.cpp

[Chris Lattner]

On Oct 18, 2012, at 2:58 PM, Douglas Gregor <dgregor at apple.com> wrote:

> 
> On Oct 18, 2012, at 2:52 PM, Eric Christopher <echristo at gmail.com> wrote:
> 
>> Author: echristo
>> Date: Thu Oct 18 16:52:18 2012
>> New Revision: 166236
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=166236&view=rev
>> Log:
>> Add a new option for and disable column number information as there
>> are no known current users of column info. Robustify and fix up
>> a few tests in the process. Reduces the size of debug information
>> by a small amount.
> 
> 
> I'd rather we try to optimize column-number computation first. If we can make it fast enough, we don't need to add this tweaking flag.

Did you take a look at the comments in the PR?  There is no known client of this information, it bloats debug information, and it forces computation (which, yes, could be sped up) that isn't otherwise needed.  It seems like clearly the wrong thing to enable by default.

When/if we want to enable it by default, it can be carefully measured and other options can be considered (maybe subexpression range info, not just line/col info, etc).

-Chris