llvm dev - Sep 2007 - [LLVMdev] Crash on accessing deleted MBBs (new backend)

Yeah, that will cause problems. However, I expect an assertion  
somewhere. Any chance you can track down the exact problem?

Thanks.

Evan

On Sep 28, 2007, at 1:37 PM, Andreas Fredriksson  
<deplinenoise at gmail.com> wrote:
> Replying to my self here. It seems I was missing an isTerminator = 1
> on the branch instruction in question, so LLVM didn't know that the
> instruction terminated a basic block. Does that make sense, or is just
> masking some other problem?
>
> Thanks,
> Andreas
>
> On 9/28/07, Andreas Fredriksson <deplinenoise at gmail.com> wrote:
>> Hi,
>> I'm trying to write up my little m68k backend things have been
going
>> smoothly. I've been working with the x86 backend as a template,  
>> fixing
>> things as I go.
>>
>> Now I've run into branches and I have a crash I don't really
>> understand. Here's the sample IR I'm running llc on to generate
>> assembly:
>> <snip>
>> llc crashes at this point because the target branch of the BLT  
>> (branch
>> if lower than) has gone away. On my win32 box it's filled with
>> 0xfeeefeee (deleted data).
>>
>> I've verified that the block is actually removed by the branch
>> folding, but for some reason this poor BLT instruction never hears
>> about that. What can I do to fix this?
>>
>> Thanks,
>> Andreas
>>
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I guess isUnpredicatedTerminator() and friends would just return
false, but maybe there should be an assertion in an earlier pass that
all instructions in the tail position of basic blocks really are
terminators, or is that not required?

// A

On 9/29/07, Evan Cheng <evan.cheng at apple.com>
wrote:
> Yeah, that will cause problems. However, I expect an assertion
> somewhere. Any chance you can track down the exact problem?
>
> Thanks.
>
> Evan
>

Please file a bug so I will remember to take a look. Thanks.

Evan

On Sep 29, 2007, at 2:49 AM, Andreas Fredriksson wrote:
> I guess isUnpredicatedTerminator() and friends would just return
> false, but maybe there should be an assertion in an earlier pass that
> all instructions in the tail position of basic blocks really are
> terminators, or is that not required?
>
> // A
>
> On 9/29/07, Evan Cheng <evan.cheng at apple.com> wrote:
>> Yeah, that will cause problems. However, I expect an assertion
>> somewhere. Any chance you can track down the exact problem?
>>
>> Thanks.
>>
>> Evan
>>
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