llvm dev - Mar 2013 - [LLVMdev] PROPOSAL: struct-access-path aware TBAA

On Mar 11, 2013, at 12:14 PM, Krzysztof Parzyszek wrote:
> On 3/11/2013 1:41 PM, Manman Ren wrote:
>> 
>>   |  x  |
>>          extends
>>   |    z         |
>>       super-type
>>            |  y  |
> 
> What does this mean?  "The type of z extends the type of x, and the
type of z is a super-type of y"?
Extends x into a subobject z, and z is a super-type of y.

-Manman
> 
> -Krzysztof
> 
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What cases does this proposal solve that the current analyses don't?  Do 
you have a motivating example?

-Krzysztof

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, 
hosted by The Linux Foundation

On Mar 12, 2013, at 8:22 AM, Krzysztof Parzyszek wrote:
> What cases does this proposal solve that the current analyses don't? 
Do you have a motivating example?
Given
  struct A {
    int x;
    int y;
  };
  struct B {
    A a;
    int z;
  };
  struct C {
    B b1;
    B b2;
  };
  struct D {
    C c;
  };

with struct-access-path aware TBAA, C::b1.a.x does not alias with D::c.b2.a.x.
without it, the 2 scalar accesses can alias since both have int type.

Manman
> 
> -Krzysztof
> 
> -- 
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted
by The Linux Foundation