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rust/tests/mir-opt/instsimplify/casts.roundtrip.InstSimplify-after-simplifycfg.diff

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Perform instsimplify before inline to eliminate some trivial calls
2024-07-27 14:36:17 +08:00
- // MIR for `roundtrip` before InstSimplify-after-simplifycfg
+ // MIR for `roundtrip` after InstSimplify-after-simplifycfg
FileCheck casts.
2023-10-16 19:58:20 +00:00
fn roundtrip(_1: *const u8) -> *const u8 {
debug x => _1;
let mut _0: *const u8;
Never consider raw pointer casts to be trival HIR typeck tries to figure out which casts are trivial by doing them as coercions and seeing whether this works. Since HIR typeck is oblivious of lifetimes, this doesn't work for pointer casts that only change the lifetime of the pointee, which are, as borrowck will tell you, not trivial. This change makes it so that raw pointer casts are never considered trivial. This also incidentally fixes the "trivial cast" lint false positive on the same code. Unfortunately, "trivial cast" lints are now never emitted on raw pointer casts, even if they truly are trivial. This could be fixed by also doing the lint in borrowck for raw pointers specifically.
2023-07-02 17:50:24 +02:00
let mut _2: *const u8;
let mut _3: *mut u8;
let mut _4: *const u8;
FileCheck casts.
2023-10-16 19:58:20 +00:00
bb0: {
StorageLive(_2);
StorageLive(_3);
Never consider raw pointer casts to be trival HIR typeck tries to figure out which casts are trivial by doing them as coercions and seeing whether this works. Since HIR typeck is oblivious of lifetimes, this doesn't work for pointer casts that only change the lifetime of the pointee, which are, as borrowck will tell you, not trivial. This change makes it so that raw pointer casts are never considered trivial. This also incidentally fixes the "trivial cast" lint false positive on the same code. Unfortunately, "trivial cast" lints are now never emitted on raw pointer casts, even if they truly are trivial. This could be fixed by also doing the lint in borrowck for raw pointers specifically.
2023-07-02 17:50:24 +02:00
StorageLive(_4);
_4 = copy _1;
_3 = move _4 as *mut u8 (PtrToPtr);
Ban `ArrayToPointer` and `MutToConstPointer` from runtime MIR Apparently MIR borrowck cares about at least one of these for checking variance. In runtime MIR, though, there's no need for them as `PtrToPtr` does the same thing. (Banning them simplifies passes like GVN that no longer need to handle multiple cast possibilities.)
2024-06-12 01:22:31 -07:00
_2 = move _3 as *const u8 (PtrToPtr);
Never consider raw pointer casts to be trival HIR typeck tries to figure out which casts are trivial by doing them as coercions and seeing whether this works. Since HIR typeck is oblivious of lifetimes, this doesn't work for pointer casts that only change the lifetime of the pointee, which are, as borrowck will tell you, not trivial. This change makes it so that raw pointer casts are never considered trivial. This also incidentally fixes the "trivial cast" lint false positive on the same code. Unfortunately, "trivial cast" lints are now never emitted on raw pointer casts, even if they truly are trivial. This could be fixed by also doing the lint in borrowck for raw pointers specifically.
2023-07-02 17:50:24 +02:00
StorageDead(_4);
FileCheck casts.
2023-10-16 19:58:20 +00:00
StorageDead(_3);
Never consider raw pointer casts to be trival HIR typeck tries to figure out which casts are trivial by doing them as coercions and seeing whether this works. Since HIR typeck is oblivious of lifetimes, this doesn't work for pointer casts that only change the lifetime of the pointee, which are, as borrowck will tell you, not trivial. This change makes it so that raw pointer casts are never considered trivial. This also incidentally fixes the "trivial cast" lint false positive on the same code. Unfortunately, "trivial cast" lints are now never emitted on raw pointer casts, even if they truly are trivial. This could be fixed by also doing the lint in borrowck for raw pointers specifically.
2023-07-02 17:50:24 +02:00
- _0 = move _2 as *const u8 (PtrToPtr);
+ _0 = move _2;
FileCheck casts.
2023-10-16 19:58:20 +00:00
StorageDead(_2);
return;
}
}
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