ConstProp: Correctly remove const if unknown value assigned to it.
Closes#118328
The problematic sequence of MIR is:
```rust
_1 = const 0_usize;
_1 = const _; // This is an associated constant we can't know before monomorphization.
_0 = _1;
```
1. When `ConstProp::visit_assign` happens on `_1 = const 0_usize;`, it records that `0x0usize` is the value for `_1`.
2. Next `visit_assign` happens on `_1 = const _;`. Because the rvalue `.has_param()`, it can't be const evaled.
3. Finaly, `visit_assign` happens on `_0 = _1;`. Here it would think the value of `_1` was `0x0usize` from step 1.
The solution is to remove consts when checking the RValue fails, as they may have contained values that should now be invalidated, as that local was overwritten.
This should probably be back-ported to beta. Stable is more iffy, as it's gone unidentified since 1.70, so I only think it's worthwhile if there's another reason for a 1.74.1 release anyway.
Add FileCheck annotations to a few MIR opt tests
const_debuginfo did not specify which passes were running.
const_prop_miscompile is renamed and moved to const_prop directory.
while_storage was broken.
It makes it sound like the `ExprKind` and `Rvalue` are supposed to represent all pointer related
casts, when in reality their just used to share a some enum variants. Make it clear there these
are only coercion to make it clear why only some pointer related "casts" are in the enum.
To reproduce the changes in this commit locally:
- Run `./x test tidy` and remove all the output files not associated
with a test file anymore, as reported by tidy.
- Run `./x test tests/mir-opt --bless` to generate the new outputs.
Implement builtin # syntax and use it for offset_of!(...)
Add `builtin #` syntax to the parser, as well as a generic infrastructure to support both item and expression position builtin syntaxes. The PR also uses this infrastructure for the implementation of the `offset_of!` macro, added by #106934.
cc `@petrochenkov` `@DrMeepster`
cc #110680 `builtin #` tracking issue
cc #106655 `offset_of!` tracking issue
ConstProp into PlaceElem::Index.
Noticed this while looking at keccak output MIR.
This pass aims to replace `ProjectionElem::Index` with `ProjectionElem::ConstantIndex` during ConstProp.
r? `@ghost`
Rename InstCombine to InstSimplify
```
╭ ➜ ben@archlinux:~/rust
╰ ➤ rg -i instcombine
src/doc/rustc-dev-guide/src/mir/optimizations.md
134:may have been misapplied. Examples of this are `InstCombine` and `ConstantPropagation`.
src/ci/docker/host-x86_64/disabled/dist-x86_64-haiku/llvm-config.sh
38: instcombine instrumentation interpreter ipo irreader lanai \
tests/codegen/slice_as_from_ptr_range.rs
4:// min-llvm-version: 15.0 (because this is a relatively new instcombine)
```
r? `@scottmcm`
Don't validate constants in const propagation
Validation is neither necessary nor desirable.
The constant validation is already omitted at mir-opt-level >= 3, so there there are not changes in MIR test output (the propagation of invalid constants is covered by an existing test in tests/mir-opt/const_prop/invalid_constant.rs).
