search for: accesstop0

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2017 Apr 11
2
[RFC] Design of a TBAA sanitizer
...;t want to > > > digress). You can also recreate the pattern with realloc. > > > > > > > In both of your examples there is no place in the program where both P0 > and > > P1 are live simultaneously, > > i.e. no analysis path is expected to query MayAlias(AccessToP0, > > AccessToP1). No? > > I may be misunderstanding what you meant, but I don't see why not. > > Say you had (all values are SSA values): > > %p0 = malloc() > store i32 0, i32* %p0 // S0 > free(%p0) > %p1 = malloc() > store i32 1, i32* %p1 // S1 > > a...
2017 Apr 11
2
[RFC] Design of a TBAA sanitizer
...eal soundness issue here in LLVM's semantics, but I don't want to > digress). You can also recreate the pattern with realloc. > In both of your examples there is no place in the program where both P0 and P1 are live simultaneously, i.e. no analysis path is expected to query MayAlias(AccessToP0, AccessToP1). No? > > The same problem exists with constant addresses. LLVM states that > constant locations are noalias with themselves, and you again have the > "noalias does not imply pointer inequality" problem. > That won't even have to be special cased, becaus...
2017 Apr 11
2
[RFC] Design of a TBAA sanitizer
Hi Kostya, On April 11, 2017 at 1:30:10 PM, Kostya Serebryany (kcc at google.com) wrote: > of course, but accesses are done via pointers, and if TBAA queries > MayAlias(AccessViaP1, AccessViaP2) > there should (??) be a point in the IR where both P1 and P2 exist together > and can be compared. That may not be possible (though I'm second guessing what exactly you have in mind so