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Alessandro Di Federico
9ce805415b
The Reaching Definitions Analysis used to ignore all the memory access
that were not relative to a CSV or an `alloca`. In certain situations,
in particular in x86 which makes heavy use of the stack, this led to
miss certain links that were vital for a correct identification of
certain jump targets.
As an example consider the following example:
cmp DWORD PTR [rbx+0x8],0x5
ja 4bc5c8 <uw_update_context_1+0x148>
mov eax,DWORD PTR [rbx+0x8]
movsxd rax,DWORD PTR [r12+rax*4]
add rax,r12
jmp rax
The constaint on `rbx+0x8` is not propagated to the use after the jump,
due to a missing link.
This commit fixes this by tracking all the memory accesses within the
expressive power of the `MemoryAccess` class, in particular those
expressed as register plus offset.
Additionally, this commit also makes RDA consider as reaching
definitions for a `load` only those definitions that match exactly the
load address, while previously we were considering all the `mayAlias`
definitions. This situation, in combination with the previous change,
led to have paths with multiple reaching definitions, which was
problematic for the path sensitive merge.
Finally, we consider a definition to be clobbered only if there's an
exact store to the esame address, instead of a store on an aliasing
address.