On 28 February 2017 at 16:04, Dibyendu Majumdar <mobile@xxxxxxxxxxxxxxx> wrote:
> On 28 February 2017 at 15:09, Luc Van Oostenryck
> <luc.vanoostenryck@xxxxxxxxx> wrote:
>> On Tue, Feb 28, 2017 at 06:20:43AM +0000, Dibyendu Majumdar wrote:
>>> I am trying to debug a failure in sparse-llvm when compiling following:
>>>
>>> struct mytype {
>>> int *foo;
>>> };
>>> extern void init_mytype(struct mytype *mt);
>>> void init_mytype(struct mytype *mt) {
>>> mt->foo = (void *)0;
>>> }
>>>
>>
>> I think that the best you can do for us to be able to help you is to create
>> test case showing concretely the issues you have.
>>
>
> Above is a simple test case. If you use an LLVM build with assertions
> enabled then the code generator aborts:
>
> Assertion failed: getOperand(0)->getType() ==
> cast<PointerType>(getOperand(1)->getType())->getElementType() && "Ptr
> must be a pointer to Val type!", file
> C:\d\llvm-3.9.0.src\lib\IR\Instructions.cpp, line 1436
>
> In the details I posted I was trying to say that :
>
> a) The Expression Value does not appear to pass down the fact that it
> has found a NULL pointer - i.e. (void *)0.
> b) And even if this is conveyed (by making changes I suggested) then
> it is lost at the time of converting to value pseudo. As far as I can
> tell the cast is not being optimized away, it is just lost in
> translation.
>
> I could be wrong in my analysis as I mentioned before. I will try to
> generate some debug info to further show what seems to be happening.
>
I should add that if (int *) is used instead of (void *) in the above
example, it still aborts, although this time the changes I suggested
are not relevant.
Regards
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