Re: Debugging stack traces
Re: Debugging stack traces
- Subject: Re: Debugging stack traces
- From: Jens Alfke <email@hidden>
- Date: Wed, 2 Dec 2009 17:17:15 -0800
On Dec 2, 2009, at 4:55 PM, Graham Cox wrote:
> When I get a stack trace in a crash report, as exampled below, can I use the offsets (+71, +50) to locate the relevant line in the source code? What do these numbers actually mean?
They're byte offsets from the start of the function, in the machine code.
I don't know of a good way to convert these back into line numbers. If you have that exact same version of the code open in Xcode (including configuration and architecture) you can choose Build > Show Assembly Code, then look for the function in the assembly; there are ".line" directives that show source line numbers, but unfortunately that listing doesn't show byte offsets. Or you can use otool to disassemble the function out of the binary, which includes the offsets but not the line numbers. :/
If you manage to solve that, you then have the lesser problem that optimized code is often heavily rearranged from the way it looks in the source, so the line numbers may not make much sense.
—Jens_______________________________________________
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