[LLVMdev] DataStructure Analysis ds-aa can not stop when passing mysqld

[Andrew Lenharth]

On Wed, May 13, 2009 at 1:36 PM,  <hc2428 at columbia.edu> wrote:
> Quoting Chris Lattner <clattner at apple.com>:
>
> Dear staff,
>     I am using the ds-aa to pass mysqld. I compile mysqld 4.0.12
> statically (compile all libraries statically to the executable) and
> got the bc file, named it as mysqld.bc3.
>     I use the command to pass:
>
> opt -load <poolalloc install dir>/lib/libLLVMDataStructure.so -ds-aa
> mysqld.bc3 -print-alias-sets -disable-output
>
>     However, I got a lot of "cast in ... " on output screen like this:
>
> cast in strxnmov
>         %13 = inttoptr i32 %10 to i8*           ; <i8*> [#uses=1]
>
>     In addition, and pass can not stop for a long time, and the last
> output is the "cast in ... " as above.

inttoptr casts are very bad for alias analysis.  DSA has some code in
it these days to try to track common inttoptr idioms, but this code
likely doesn't scale well.

Andrew

> Thanks,
> Heming
>
>
>>
>> On May 13, 2009, at 7:22 AM, Stripf, Timo wrote:
>>
>>> Hi all,
>>>
>>> i?m working atm on a backend for a processor architecture that is
>>> capable of storing the carry flag of ADDC in an 1-bit register
>>> class. So I tried to lower the ADDC instruction to generate two
>>> register values as result. On the tablegen description of the
>>> instruction i came across the tablegen restriction that only one
>>> output result of one instruction is possible:
>>>
>>>  assert(NumResults <= 1 &&
>>>         "We only work with nodes with zero or one result so far!");
>>>
>>> So my question is now how much work it would be to remove this
>>> restriction in tablegen. What do I have to take into consideration?
>>>
>>
>> I don't know offhand, but this would be a very welcome improvement!
>>
>> -Chris
>
>
>
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