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Revert "store ScalarPair via memset when one side is undef and the other side can be memset" #137894

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Merged
merged 2 commits into from
Mar 4, 2025
Merged

Revert "store ScalarPair via memset when one side is undef and the other side can be memset" #137894

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a59a8f9
Revert "Auto merge of #135335 - oli-obk:push-zxwssomxxtnq, r=saethlin"
compiler-errors Mar 2, 2025
5f575bc
Add a test
compiler-errors Mar 2, 2025
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14 changes: 14 additions & 0 deletions tests/codegen/slice-init.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -89,6 +89,20 @@ pub fn option_none_init() -> [Option<u8>; N] {
[None; N]
}

use std::mem::MaybeUninit;

// FIXME: This could be optimized into a memset.
// Regression test for <https://github.com/rust-lang/rust/issues/137892>.
#[no_mangle]
pub fn half_uninit() -> [(u128, MaybeUninit<u128>); N] {
// CHECK-NOT: select
// CHECK: br label %repeat_loop_header{{.*}}
// CHECK-NOT: switch
// CHECK: icmp
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@compiler-errors compiler-errors Mar 2, 2025

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I copied all this from above :clueless:

// CHECK-NOT: call void @llvm.memset.p0
[const { (0, MaybeUninit::uninit()) }; N]
}

// Use an opaque function to prevent rustc from removing useless drops.
#[inline(never)]
pub fn opaque(_: impl Sized) {}
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