This commit drops libptc in favor of its new form libtcg.
It brings several improvements, among which:
* The QEMU version we work on has been upgraded.
* CPUStateAccessAnalysis has been reimplemented in a way that makes it
easier to debug and solves some limitations (e.g., tracking leaking
pointers).
* Identification of pieces of the CPU state that are read by each helper
and fixing access to the CPU state is now performed at build-time.
* We no longer mmap the code we need to translate, dropping all the
issues related to code that needed to be mapped where something is
already present.
* We now have two distinct flavors of helper modules: the full one and
the "slim" one. The latter contains the definition only of functions
we intend to inline. It is used in most of the pipeline, a good thing
since we spend less time optimizing code we don't really care about.
The full module is only used on the re-compilation branch of the
pipeline.
* We no longer split the `cpu_loop` function.
* We change MetaAddress to rely on architectures from `model::` as
opposed to the LLVM ones.
* We no longer attach debug info to LLVM IR containing the original
assembly.
* We now verify that the lifted code only contains code we expect.
This commit a non-deterministic bug on ARM's switch-disjoint-ranges
test.
The problem was that we were setting as initial nodes of the monotone
framework all the nodes that are not reachable from the nodes classified
as initial nodes *so far*.
This approach is susceptible to the visit order.
Classifying certain nodes as entry nodes degrades the analysis results
since we associates a top value to them.
Electing initial nodes by traversing a list of nodes sorted by dominance
solves this problem.
This commit introduces a change in AdvancedValueInfoMFI which forces to
consider constraints valid on 32-bit values to be valid on their
untruncated 64-bit counterparts.
While being unsound, this is important to easily devirtualize indirect
branches on 64-bit architectures where often constraints are expressed
on 32-bit switch values.
`ValueMaterializer` is a rewrite of what was called `AdvancedValueInfo`
which follows the same principles.
The main benefits over the old version is:
* We materialize the data-flow graph and the CFG of the relevant part of
root. This makes debugging significantly easier.
* We drop the old MonotoneFramework infrastructure in favor of
getMaximalFixedPoint.
* We significantly reduce the amount of queries we make to
AdvancedValueInfo.
Giacomo Vercesi