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fix related miri variables 

rename variables like below
 - Value => ConstValue
 - PrimVal => Scalar
 - Value::ByVal => ConstValue::Scalar
 - Value::ByValPair => ConstValue::ScalarPair
This commit is contained in:
rchaser53 2019-01-19 23:48:13 +09:00
parent f12784bc2e
commit a626917262
2 changed files with 11 additions and 11 deletions
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6
src/const-eval.md
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@ -30,9 +30,9 @@ used) and a `GlobalId`. The `GlobalId` is made up of an
Constant evaluation returns a `Result` with either the error, or the simplest Constant evaluation returns a `Result` with either the error, or the simplest
representation of the constant. "simplest" meaning if it is representable as an representation of the constant. "simplest" meaning if it is representable as an
integer or fat pointer, it will directly yield the value (via `Value::ByVal` or integer or fat pointer, it will directly yield the value (via `ConstValue::Scalar` or
`Value::ByValPair`), instead of referring to the [`miri`](./miri.html) virtual `ConstValue::ScalarPair`), instead of referring to the [`miri`](./miri.html) virtual
memory allocation (via `Value::ByRef`). This means that the `const_eval` memory allocation (via `ConstValue::ByRef`). This means that the `const_eval`
function cannot be used to create miri-pointers to the evaluated constant or function cannot be used to create miri-pointers to the evaluated constant or
static. If you need that, you need to directly work with the functions in static. If you need that, you need to directly work with the functions in
[src/librustc_mir/const_eval.rs](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_mir/const_eval/index.html). [src/librustc_mir/const_eval.rs](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_mir/const_eval/index.html).

16
src/miri.md
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@ -55,18 +55,18 @@ Before the evaluation, a virtual memory location (in this case essentially a
`vec![u8; 4]` or `vec![u8; 8]`) is created for storing the evaluation result. `vec![u8; 4]` or `vec![u8; 8]`) is created for storing the evaluation result.
At the start of the evaluation, `_0` and `_1` are At the start of the evaluation, `_0` and `_1` are
`Value::ByVal(PrimVal::Undef)`. When the initialization of `_1` is invoked, the `ConstValue::Scalar(Scalar::Undef)`. When the initialization of `_1` is invoked, the
value of the `FOO` constant is required, and triggers another call to value of the `FOO` constant is required, and triggers another call to
`tcx.const_eval`, which will not be shown here. If the evaluation of FOO is `tcx.const_eval`, which will not be shown here. If the evaluation of FOO is
successful, 42 will be subtracted by its value `4096` and the result stored in successful, 42 will be subtracted by its value `4096` and the result stored in
`_1` as `Value::ByValPair(PrimVal::Bytes(4054), PrimVal::Bytes(0))`. The first `_1` as `ConstValue::ScalarPair(Scalar::Bytes(4054), Scalar::Bytes(0))`. The first
part of the pair is the computed value, the second part is a bool that's true if part of the pair is the computed value, the second part is a bool that's true if
an overflow happened. an overflow happened.
The next statement asserts that said boolean is `0`. In case the assertion The next statement asserts that said boolean is `0`. In case the assertion
fails, its error message is used for reporting a compile-time error. fails, its error message is used for reporting a compile-time error.
Since it does not fail, `Value::ByVal(PrimVal::Bytes(4054))` is stored in the Since it does not fail, `ConstValue::Scalar(Scalar::Bytes(4054))` is stored in the
virtual memory was allocated before the evaluation. `_0` always refers to that virtual memory was allocated before the evaluation. `_0` always refers to that
location directly. location directly.
@ -75,7 +75,7 @@ After the evaluation is done, the virtual memory allocation is interned into the
miri, but just extract the value from the interned allocation. miri, but just extract the value from the interned allocation.
The `tcx.const_eval` function has one additional feature: it will not return a The `tcx.const_eval` function has one additional feature: it will not return a
`ByRef(interned_allocation_id)`, but a `ByVal(computed_value)` if possible. This `ByRef(interned_allocation_id)`, but a `Scalar(computed_value)` if possible. This
makes using the result much more convenient, as no further queries need to be makes using the result much more convenient, as no further queries need to be
executed in order to get at something as simple as a `usize`. executed in order to get at something as simple as a `usize`.
@ -83,15 +83,15 @@ executed in order to get at something as simple as a `usize`.
Miri's core datastructures can be found in Miri's core datastructures can be found in
[librustc/mir/interpret](https://github.com/rust-lang/rust/blob/master/src/librustc/mir/interpret). [librustc/mir/interpret](https://github.com/rust-lang/rust/blob/master/src/librustc/mir/interpret).
This is mainly the error enum and the `Value` and `PrimVal` types. A `Value` can This is mainly the error enum and the `ConstValue` and `Scalar` types. A `ConstValue` can
be either `ByVal` (a single `PrimVal`), `ByValPair` (two `PrimVal`s, usually fat be either `Scalar` (a single `Scalar`), `ScalarPair` (two `Scalar`s, usually fat
pointers or two element tuples) or `ByRef`, which is used for anything else and pointers or two element tuples) or `ByRef`, which is used for anything else and
refers to a virtual allocation. These allocations can be accessed via the refers to a virtual allocation. These allocations can be accessed via the
methods on `tcx.interpret_interner`. methods on `tcx.interpret_interner`.
If you are expecting a numeric result, you can use `unwrap_u64` (panics on If you are expecting a numeric result, you can use `unwrap_u64` (panics on
anything that can't be representad as a `u64`) or `to_raw_bits` which results anything that can't be representad as a `u64`) or `to_raw_bits` which results
in an `Option<u128>` yielding the `ByVal` if possible. in an `Option<u128>` yielding the `Scalar` if possible.
## Allocations ## Allocations
@ -113,7 +113,7 @@ to a pointer to `b`.
Although the main entry point to constant evaluation is the `tcx.const_eval` Although the main entry point to constant evaluation is the `tcx.const_eval`
query, there are additional functions in query, there are additional functions in
[librustc_mir/const_eval.rs](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_mir/const_eval/index.html) [librustc_mir/const_eval.rs](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_mir/const_eval/index.html)
that allow accessing the fields of a `Value` (`ByRef` or otherwise). You should that allow accessing the fields of a `ConstValue` (`ByRef` or otherwise). You should
never have to access an `Allocation` directly except for translating it to the never have to access an `Allocation` directly except for translating it to the
compilation target (at the moment just LLVM). compilation target (at the moment just LLVM).