Re: How many bytes is an instruction?
Re: How many bytes is an instruction?
- Subject: Re: How many bytes is an instruction?
- From: Rick Mann <email@hidden>
- Date: Wed, 24 Jul 2013 14:03:24 -0700
On Jul 24, 2013, at 13:54 , Jerry Krinock <email@hidden> wrote:
>
> On 2013 Jul 24, at 12:30, Rick Mann <email@hidden> wrote:
>
>> I've got a crash log without good symbolication. It shows the crash as myMethod:+657.
>
> The call (line) *above* myMethod:+657 should tell you the procedure which was called by myMethod where the crash occurred. Unless you write really long methods, the answer should jump out at you.
>
>> Can I look at disassembly of the file in Xcode and gauge approximately where that crash occurred by counting instructions? Is there a rule of thumb I can use for instruction width?
>
> You shouldn't need to.
>
> If this doesn't make sense, post more of that crash report.
The crash is actually down deeper than that. I'm fairly sure I know what the cause was, and later symbolication showed I was correct, but in general, I wanted to see how to find the offset. Seems like the assembler should be able to output relative address offsets in some form (perhaps with an extra option Xcode doesn't pass because it's trying to make input that the assembler can accept.
In this case, an exception was thrown when inserting nil into a NSCFPlaceholderDictionary. I had a line of code creating a dictionary literal. But it's possible that the dictionary could've been created deep inside Cocoa, in which case it wouldn't have been so obvious. I wanted to try to pinpoint the line of my code that made the offending call. Knowing relative offsets into the assembly would make that a little easier.
--
Rick
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