> by applying a union used in one part of the code to another to replace a dereferencing cast
Type punning via pointer casts often violates the "strict aliasing rules" and the compiler might do wonky optimizations. Type punning via unions, on the other hand, is explicitly allowed in C. It is *not* allowed in C++, although in practice I haven't encountered a case where it didn't work. (The legal way to do type punning in C++ has been memcpy() , which gets fully optimized away; C++20 finally has std::bit_cast()).
You probably know this anyway. Just writing for other people who are reading :-)
Christof
The stack trace was really not that useful, but I did look into the dip-specific functions.
In the end I think I fixed it, but I'm not 100% sure how. I did some simple cleanup in the float sample conversion by applying a union used in one part of the code to another to replace a dereferencing cast. That seems to have helped, at least in my testing so far.
On Feb 8, 2020, at 12:00 PM, pd-dev-request@lists.iem.at wrote:
Message: 2
Date: Sat, 8 Feb 2020 11:06:30 +0100
From: Christof Ressi <info@christofressi.com>
To: pd-dev@lists.iem.at
Subject: Re: [PD-dev] Tips on debugging dip crashes?
Message-ID: <99ab2074-1961-26c3-7d75-1de6067435f6@christofressi.com>
Content-Type: text/plain; charset="windows-1252"; Format="flowed"
Hi Dan,
if you're accidentally writing beyond the stack, then the backtrace
becomes useless. You can notice this by looking at the function
addresses/names. If they have low addresses like 0x9 or don't show a
name (although Pd is built with debug symbols), than this is strong
indication for a stack overflow. Sometimes GDB will detect a stack overflow.
Two things you can do: 1) set appropiate breakpoints in the debugger to
find out where it crashes 2) good ol' printf-debugging :-)
I'm currently working on a complicated external and I highly appreciate
the visual debugging tools IDEs like QtCreator give me.
Maybe you can post the stacktrace?
Christof
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