Module miri::interpret

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An interpreter for MIR used in CTFE and by miri


A lot of the flexibility above is just needed for Miri, but all “compile-time” machines (CTFE and ConstProp) use the same instance. Here, we share that code.


The information that makes up a memory access: offset and size.
A reference to some allocation that was already bounds-checked for the given region and had the on-access machine hooks run.
A reference to some allocation that was already bounds-checked for the given region and had the on-access machine hooks run.
This type represents an Allocation in the Miri/CTFE core engine.
Represents the result of const evaluation via the eval_to_allocation query.
Interned types generally have an Outer type and an Inner type, where Outer is a newtype around Interned<Inner>, and all the operations are done on Outer, because all occurrences are interned. E.g. Ty is an outer type and TyKind is its inner type.
A stack frame.
What we store about a frame in an interpreter backtrace.
Uniquely identifies one of the following:
Packages the kind of error we got from the const code interpreter up with a Rust-level backtrace of where the error occurred. These should always be constructed by calling .into() on an InterpError. In rustc_mir::interpret, we have throw_err_* macros for this.
Input argument for tcx.lit_to_const.
State of a local variable including a memoized layout
A MemPlace with its layout. Constructing it is only possible in this module.
Represents a pointer in the Miri engine.
State for tracking recursive validation of references
Information about a size mismatch.
Details of an access to uninitialized bytes where it is not allowed.


We have our own error type that does not know about the AllocId; that information is added when converting to InterpError.
The return value of get_alloc_info indicates the “kind” of the allocation.
Details of why a pointer had to be in-bounds.
Represents a constant value in Rust. Scalar and Slice are optimizations for array length computations, enum discriminants and the pattern matching logic.
Extra things to check for during validation of CTFE results.
The value of a function pointer.
An allocation in the global (tcx-managed) memory can be either a function pointer, a static, or a “real” allocation with some data in it.
An Immediate represents a single immediate self-contained Rust value.
A contiguous chunk of initialized or uninitialized memory.
Error information for when the program we executed turned out not to actually be a valid program. This cannot happen in stand-alone Miri, but it can happen during CTFE/ConstProp where we work on generic code or execution does not have all information available.
Error type for tcx.lit_to_const.
Current value of a local variable
Information required for the sound usage of a MemPlace.
An Operand is the result of computing a mir::Operand. It can be immediate, or still in memory. The latter is an optimization, to delay reading that chunk of memory and to avoid having to store arbitrary-sized data here.
Error information for when the program exhausted the resources granted to it by the interpreter.
A Scalar represents an immediate, primitive value existing outside of a memory::Allocation. It is in many ways like a small chunk of an Allocation, up to 16 bytes in size. Like a range of bytes in an Allocation, a Scalar can either represent the raw bytes of a simple value or a pointer into another Allocation
Data returned by Machine::stack_pop, to provide further control over the popping of the stack frame
Unwind information.
Error information for when the program caused Undefined Behavior.
Error information for when the program did something that might (or might not) be correct to do according to the Rust spec, but due to limitations in the interpreter, the operation could not be carried out. These limitations can differ between CTFE and the Miri engine, e.g., CTFE does not support dereferencing pointers at integral addresses.


The functionality needed by memory to manage its allocations
Methods of this trait signifies a point where CTFE evaluation would fail and some use case dependent behaviour can instead be applied.
A trait for machine-specific errors (or other “machine stop” conditions).
Whether this kind of memory is allowed to leak
How to traverse a value and what to do when we are at the leaves.
This trait abstracts over the kind of provenance that is associated with a Pointer. It is mostly opaque; the Machine trait extends it with some more operations that also have access to some global state. The Debug rendering is used to distplay bare provenance, and for the default impl of fmt.
A thing that we can project into, and that has a layout. This wouldn’t have to depend on Machine but with the current type inference, that’s just more convenient to work with (avoids repeating all the Machine bounds).
How to traverse a value and what to do when we are at the leaves.


Free-starting constructor for less syntactic overhead.
Gets the bytes of a constant slice value.
Intern ret and everything it references.

Type Definitions