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debug-assert ptr sanity in ptr::write #69509

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Merged
bors merged 4 commits into from
Mar 20, 2020
Merged

debug-assert ptr sanity in ptr::write #69509

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058ff72
debug-assert ptr sanity in ptr::write
RalfJung Feb 27, 2020
59350e4
increase slack for stack size test
RalfJung Feb 17, 2020
139a8c3
fix a codegen test
RalfJung Mar 12, 2020
c95f08a
increase stack slack for x86_64-pc-windows-gnu
RalfJung Mar 18, 2020
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4 changes: 1 addition & 3 deletions src/libcore/ptr/mod.rs
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Expand Up @@ -810,9 +810,7 @@ pub unsafe fn read_unaligned<T>(src: *const T) -> T {
#[inline]
#[stable(feature = "rust1", since = "1.0.0")]
pub unsafe fn write<T>(dst: *mut T, src: T) {
// FIXME: the debug assertion here causes codegen test failures on some architectures.
// See <https://github.com/rust-lang/rust/pull/69208#issuecomment-591326757>.
// debug_assert!(is_aligned_and_not_null(dst), "attempt to write to unaligned or null pointer");
debug_assert!(is_aligned_and_not_null(dst), "attempt to write to unaligned or null pointer");
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intrinsics::move_val_init(&mut *dst, src)
}

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7 changes: 1 addition & 6 deletions src/test/codegen/repeat-trusted-len.rs
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Expand Up @@ -5,14 +5,9 @@

use std::iter;

// CHECK: @helper([[USIZE:i[0-9]+]] %_1)
#[no_mangle]
pub fn helper(_: usize) {
}

// CHECK-LABEL: @repeat_take_collect
#[no_mangle]
pub fn repeat_take_collect() -> Vec<u8> {
// CHECK: call void @llvm.memset.p0i8.[[USIZE]](i8* {{(nonnull )?}}align 1{{.*}} %{{[0-9]+}}, i8 42, [[USIZE]] 100000, i1 false)
// CHECK: call void @llvm.memset.p0i8.i{{[0-9]+}}(i8* {{(nonnull )?}}align 1{{.*}} %{{[0-9]+}}, i8 42, i{{[0-9]+}} 100000, i1 false)
iter::repeat(42).take(100000).collect()
}
4 changes: 2 additions & 2 deletions src/test/ui/issues/issue-40883.rs
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Expand Up @@ -78,8 +78,8 @@ fn verify_stack_usage(before_ptr: *mut Vec<Big>) {
let stack_usage = isize::abs(
(&mut stack_var as *mut _ as isize) -
(before_ptr as isize)) as usize;
// give space for 2 copies of `Big` + 128 "misc" bytes.
if stack_usage > mem::size_of::<Big>() * 2 + 128 {
// give space for 2 copies of `Big` + 256 "misc" bytes.
if stack_usage > mem::size_of::<Big>() * 2 + 256 {
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@eddyb eddyb Mar 12, 2020 •
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Could this constant be binary searched so it's less than double the previous value?

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@RalfJung RalfJung Mar 12, 2020

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I thought powers of two were nice, but sure. ;)

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@RalfJung RalfJung Mar 12, 2020

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208 is the smallest value that works for me.
But I am a bit worried it might be larger for other platforms / architectures.

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@eddyb eddyb Mar 12, 2020

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We don't support a target with larger sizes/alignments than x64 I don't think.

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@eddyb eddyb Mar 12, 2020 •
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Oh nevermind, they could less efficient in their stack usage even if the types aren't larger.

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@RalfJung RalfJung Mar 12, 2020

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Yeah that's what I meant.

panic!("used {} bytes of stack, but `struct Big` is only {} bytes",
stack_usage, mem::size_of::<Big>());
}
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