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Also InstSimplify &raw*

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We do this for `&*` and `&mut*` already; might as well do it for raw pointers too.
This commit is contained in:
Scott McMurray 2024-05-30 22:05:30 -07:00
parent 366da30d55
commit 4b96e44ebb
4 changed files with 157 additions and 1 deletions
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2
compiler/rustc_mir_transform/src/instsimplify.rs
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@ -123,7 +123,7 @@ impl<'tcx> InstSimplifyContext<'tcx, '_> {
/// Transform `&(*a)` ==> `a`.
fn simplify_ref_deref(&self, source_info: &SourceInfo, rvalue: &mut Rvalue<'tcx>) {
if let Rvalue::Ref(_, _, place) = rvalue {
if let Rvalue::Ref(_, _, place) | Rvalue::AddressOf(_, place) = rvalue {
if let Some((base, ProjectionElem::Deref)) = place.as_ref().last_projection() {
if rvalue.ty(self.local_decls, self.tcx) != base.ty(self.local_decls, self.tcx).ty {
return;

58
tests/mir-opt/instsimplify/ref_of_deref.pointers.InstSimplify.diff Normal file
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@ -0,0 +1,58 @@
- // MIR for `pointers` before InstSimplify
+ // MIR for `pointers` after InstSimplify
fn pointers(_1: *const [i32], _2: *mut i32) -> () {
debug const_ptr => _1;
debug mut_ptr => _2;
let mut _0: ();
let _3: &[i32];
scope 1 {
debug _a => _3;
let _4: &i32;
scope 2 {
debug _b => _4;
let _5: &mut i32;
scope 3 {
debug _c => _5;
let _6: *const [i32];
scope 4 {
debug _d => _6;
let _7: *const i32;
scope 5 {
debug _e => _7;
let _8: *mut i32;
scope 6 {
debug _f => _8;
}
}
}
}
}
}
bb0: {
StorageLive(_3);
_3 = &(*_1);
StorageLive(_4);
_4 = &(*_2);
StorageLive(_5);
_5 = &mut (*_2);
StorageLive(_6);
- _6 = &raw const (*_1);
+ _6 = _1;
StorageLive(_7);
_7 = &raw const (*_2);
StorageLive(_8);
- _8 = &raw mut (*_2);
+ _8 = _2;
_0 = const ();
StorageDead(_8);
StorageDead(_7);
StorageDead(_6);
StorageDead(_5);
StorageDead(_4);
StorageDead(_3);
return;
}
}

58
tests/mir-opt/instsimplify/ref_of_deref.references.InstSimplify.diff Normal file
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@ -0,0 +1,58 @@
- // MIR for `references` before InstSimplify
+ // MIR for `references` after InstSimplify
fn references(_1: &i32, _2: &mut [i32]) -> () {
debug const_ref => _1;
debug mut_ref => _2;
let mut _0: ();
let _3: &i32;
scope 1 {
debug _a => _3;
let _4: &[i32];
scope 2 {
debug _b => _4;
let _5: &mut [i32];
scope 3 {
debug _c => _5;
let _6: *const i32;
scope 4 {
debug _d => _6;
let _7: *const [i32];
scope 5 {
debug _e => _7;
let _8: *mut [i32];
scope 6 {
debug _f => _8;
}
}
}
}
}
}
bb0: {
StorageLive(_3);
- _3 = &(*_1);
+ _3 = _1;
StorageLive(_4);
_4 = &(*_2);
StorageLive(_5);
- _5 = &mut (*_2);
+ _5 = _2;
StorageLive(_6);
_6 = &raw const (*_1);
StorageLive(_7);
_7 = &raw const (*_2);
StorageLive(_8);
_8 = &raw mut (*_2);
_0 = const ();
StorageDead(_8);
StorageDead(_7);
StorageDead(_6);
StorageDead(_5);
StorageDead(_4);
StorageDead(_3);
return;
}
}

40
tests/mir-opt/instsimplify/ref_of_deref.rs Normal file
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@ -0,0 +1,40 @@
//@ test-mir-pass: InstSimplify
#![crate_type = "lib"]
#![feature(raw_ref_op)]
// For each of these, only 2 of the 6 should simplify,
// as the others have the wrong types.
// EMIT_MIR ref_of_deref.references.InstSimplify.diff
// CHECK-LABEL: references
pub fn references(const_ref: &i32, mut_ref: &mut [i32]) {
// CHECK: _3 = _1;
let _a = &*const_ref;
// CHECK: _4 = &(*_2);
let _b = &*mut_ref;
// CHECK: _5 = _2;
let _c = &mut *mut_ref;
// CHECK: _6 = &raw const (*_1);
let _d = &raw const *const_ref;
// CHECK: _7 = &raw const (*_2);
let _e = &raw const *mut_ref;
// CHECK: _8 = &raw mut (*_2);
let _f = &raw mut *mut_ref;
}
// EMIT_MIR ref_of_deref.pointers.InstSimplify.diff
// CHECK-LABEL: pointers
pub unsafe fn pointers(const_ptr: *const [i32], mut_ptr: *mut i32) {
// CHECK: _3 = &(*_1);
let _a = &*const_ptr;
// CHECK: _4 = &(*_2);
let _b = &*mut_ptr;
// CHECK: _5 = &mut (*_2);
let _c = &mut *mut_ptr;
// CHECK: _6 = _1;
let _d = &raw const *const_ptr;
// CHECK: _7 = &raw const (*_2);
let _e = &raw const *mut_ptr;
// CHECK: _8 = _2;
let _f = &raw mut *mut_ptr;
}