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.
* Make the following private headers public:
* Lift/CPUStateAccessAnalysisPass.h
* Lift/CSVOffsets.h
* Lift/PTCDump.h
* Lift/VariableManager.h
* Move from revngSupport to revngLift:
* IRAnnotators.{h,cpp}
* SelfReferencingDbgAnnotationWriter.{h,cpp}
* Move from revngSupport to revngModel:
* FunctionTags.{h,cpp}
* ProgramCounterHandler.{h,cpp}
* Move from revngSupport to revngRecompile:
* OriginalAssemblyAnnotationWriter.{h,cpp}
Improve the way in which we connect the non reachable `JumpTargets` when
rebuilding the dispatcher for non `SemanticsPreserving` `CFGForm`s.
When connecting group of jump targets that are not currently reachable
from the entry dispatcher, we elect the jump target with the lowest
program counter value, as the one to be connected to the dispatcher.
We also mark the jump targets now transitively reachables from the
elected one, as reachable, so to avoid adding other unnecessary edges
from the dispatcher.
Replace the stub implementation of invalidation with the proper
implementation. A ReadPathCache is added to each global so that it can
keep tracks of what target are associated to which read paths.
`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.
This commit adopts `llvm::DenseSet`, `llvm::DenseMap` and
`std::unordered_set` where needed.
It also tweaks some `llvm::SmallVector` sizes.
It brings an additional ~3% improvement during lifting.
This commit disables GVN in order to improve lifting performance.
It also increases `EarlyCSEMssaOptCap` so we keep catching all the jump
target we used to.
Lifting /bin/bash goes from ~29mins to ~5mins
We used to jump to the dispatcher, however we only sink to an
unreachable `anypc`. We were threfore significantly complicating the CFG
in case of indirect function calls.
Alessandro Di Federico