This mostly deals with the splitting of the old `sym` type into
two: one for dealing with expression creation, and a new simulator
backend type for dealing with control-flow and assertions.
See the writeup in Crucible.hs in this commit for details. In short, the recent
changes to generalize `PtrAdd` triggered a failing proof obligation due to a use
of `llvmPointer_bv`. The new implementation is as sound as the previous one,
but more general.
Fixes#260
Adds support in macaw-aarch32 for conditional returns. These are not supported in core macaw, and are thus architecture-specific block terminators.
This required changes to the type of arch-specific block terminators. Before, `ArchTermStmt` was only parameterized by a state thread (`ids`). This meant that they could not contain macaw (or crucible) values. Some work on. AArch32 requires being able to store condition values in arch terminators (to support conditional returns). This change modifies the `ArchTermStmt` to enable this, which requires a bit of plumbing through various definitions and some extra instances.
In support of actually using this, it also became necessary to plumb fallthrough block labels through the architecture-specific terminator translation in macaw-symbolic.
Note that this change was overdue, as the PowerPC backend was storing macaw values in a way that would have rendered them unusable in the macaw-ppc-symbolic translation, had any interpretation been provided. These new changes will enable a handler to be written for the conditional PowerPC trap instructions.
PowerPC, x86, and ARM have been updated.
Improves the macaw-aarch32 tests. There is now a command line option to save the generated macaw IR for each
discovered function to /tmp. Note that this reuses some infrastructure from the macaw-symbolic tests. This
shared functionality should be extracted into a macaw-testing library.
This change adds an optional argument to `genArchVals` that allows client code to override the backend translation behavior of `MacawArchStmtExtension`s on a statement-by-statement basis. The new argument has type `Maybe (MacawArchStmtExtensionOverride arch)`, where `MacawArchStmtExtensionOverride` is a function that takes a statement and a crucible state, and returns an optional tuple containing the value produced by the statement, as well as an updated state. Returning 'Nothing' indicates that the backend should use its default handler for the statement.
Client code that wishes to maintain the existing default behavior in all cases can simply pass `Nothing` for the new argument to `genArchVals`.
GaloisInc/crucible#794 increases the number of functions that use
implicit `MemOptions`, including a handful of key LLVM memory model–related
functions. As a result, many parts of `macaw` need to add implicit `?memOpts`
parameters to accommodate to this change.
The new test suites cover x86_64, PowerPC, and ARM. They test that the semantics are actually correct (rather than just seeing if symbolic execution produces any result). The `Data.Macaw.Symbolic.Testing` module in macaw-symbolic provides some common utilities for symbolic execution engine setup, while there are tailored test harnesses for each architecture.
The semantics of the test harnesses are documented in each architecture test suite, but they:
1. Discover all of the test binaries (which are generated from the included makefiles)
2. Treat each function whose name begins with `test_` as a test entry point
3. Symbolically executes each test case with fully symbolic register states
4. Extracts the return value after symbolic execution, which is treated as the predicate to an assertion that must be proved
- If the test case is in the `pass` subdirectory, it is proved and expected to hold
- If the test case is in the `fail` subdirectory, it is proved and expected to not hold.
Each test harness supports two options for debugging:
- Dumping generated SMT queries
- Dumping generated Macaw IR for inspection
This testing uncovered a bug in the (previously untested) macaw-aarch32-symbolic code. It required a number of submodule updates to:
- Adapt to some what4 changes
- Fix a bug in the LLVM memory model that lets these tests pass
- Adapt to changes to some crucible APIs
This change also modifies the CI configuration to install SMT solvers earlier (which are now needed for all of the symbolic package tests).
This commit reduces duplication in the PowerPC backend. Instances are now in terms of the generic `AnyPPC` type, rather than having separate instances for 32 and 64 bit. Shuffling some type parameters also allows us to remove a large number of type equalities that e.g., fix the arch register type to `PPCReg`.
Update to API changes in macaw-base in macaw-ppc and macaw-arm
The "block label" abstraction (used during arch-specific disassembly) was removed some time ago in the base macaw library. This change updates macaw-ppc and macaw-arm to remove uses of block labels. The major change is that the disassembly function only returns a single block at a time instead of a sequence of blocks.
To facilitate this, the handling of the PowerPC conditional trap instruction (trap doubleword) is now an architecture-specific terminator instruction instead of encoding the logic of conditional trapping. We will now have to encode the conditional trapping logic in macaw-ppc-symbolic. Note that we have not done so yet.
This commit also updates the expected results of the PowerPC tests; the number of discovered blocks is different, but not significantly so. It is hard to tell if this is a regression or an improvement.
Except for Attn, these are all no-ops since we don't have a concurrency model.
That could change later - we might want to model them as both failing and
succeeding in some cases (esp the transactional memory instructions).
