[LLVMdev] -fomit-frame-pointer on intel darwin

Jack Howarth howarth at bromo.med.uc.edu
Mon Aug 16 11:36:29 PDT 2010

On Mon, Aug 16, 2010 at 11:07:06AM -0700, Eric Christopher wrote:
> On Aug 16, 2010, at 7:59 AM, Jack Howarth wrote:
> > Despite the absence of testsuite failures at -m32 or -m64 on either
> > i386-apple-darwin10 or x86_64-apple-darwin10, there are still some concerns
> > about the origins of the original Mach-O comment above. There also was
> > a concern that -fomit-frame-pointer would break Shark but my testing in
> > darwin10 suggests it still can profile code via the dwarf2. Thanks in
> > advance for any clarifications on the reasoning behind the original code.
> That's a long time ago :)
> At the time we needed to use the frame pointer instead of the eh frame information.  If it works for you now I don't see any harm in turning it on.
> -eric

   Thanks. Often Apple's patches came out of their own branch without a lot
of discussion in gcc-patches so I just wanted to double check that there wasn't any
obscure reason to avoid enabling omit-frame-pointer (aside from the degraded
profiling experience). We are already a tad bleeding edge anyway. On darwin10
we leveraged the linkers tolerance for omission of the eh labels to allow
-freorder-blocks-and-partition functional on darwin10 and later.

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