From 95aed7ab3b38f908d357ee5e433946639fff6b03 Mon Sep 17 00:00:00 2001 From: Ralf Jung Date: Tue, 29 Dec 2020 22:46:17 +0100 Subject: [PATCH 1/2] Miri: make size/align_of_val work for dangling raw ptrs --- compiler/rustc_mir/src/interpret/intrinsics.rs | 6 ++++-- compiler/rustc_mir/src/interpret/validity.rs | 2 +- 2 files changed, 5 insertions(+), 3 deletions(-) diff --git a/compiler/rustc_mir/src/interpret/intrinsics.rs b/compiler/rustc_mir/src/interpret/intrinsics.rs index 474e1f8e577..03f3bd34949 100644 --- a/compiler/rustc_mir/src/interpret/intrinsics.rs +++ b/compiler/rustc_mir/src/interpret/intrinsics.rs @@ -141,9 +141,11 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> { } sym::min_align_of_val | sym::size_of_val => { - let place = self.deref_operand(args[0])?; + // Avoid `deref_operand` -- this is not a deref, the ptr does not have to be + // dereferencable! + let place = self.ref_to_mplace(self.read_immediate(args[0])?)?; let (size, align) = self - .size_and_align_of(place.meta, place.layout)? + .size_and_align_of_mplace(place)? .ok_or_else(|| err_unsup_format!("`extern type` does not have known layout"))?; let result = match intrinsic_name { diff --git a/compiler/rustc_mir/src/interpret/validity.rs b/compiler/rustc_mir/src/interpret/validity.rs index 57aec0953b8..aff80dddfdf 100644 --- a/compiler/rustc_mir/src/interpret/validity.rs +++ b/compiler/rustc_mir/src/interpret/validity.rs @@ -391,7 +391,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, ' } // Make sure this is dereferenceable and all. let size_and_align = try_validation!( - self.ecx.size_and_align_of(place.meta, place.layout), + self.ecx.size_and_align_of_mplace(place), self.path, err_ub!(InvalidMeta(msg)) => { "invalid {} metadata: {}", kind, msg }, ); From f76bae924438fbf4a885fd8827d43499ab5d1f68 Mon Sep 17 00:00:00 2001 From: Ralf Jung Date: Wed, 30 Dec 2020 14:29:33 +0100 Subject: [PATCH 2/2] CTFE: test size/align_of_val_raw on dangling pointers --- library/core/src/mem/mod.rs | 6 ++++-- src/test/ui/consts/const-size_of_val-align_of_val.rs | 7 +++++++ 2 files changed, 11 insertions(+), 2 deletions(-) diff --git a/library/core/src/mem/mod.rs b/library/core/src/mem/mod.rs index e84014c68a6..70c3fded692 100644 --- a/library/core/src/mem/mod.rs +++ b/library/core/src/mem/mod.rs @@ -374,7 +374,8 @@ pub const fn size_of_val(val: &T) -> usize { /// ``` #[inline] #[unstable(feature = "layout_for_ptr", issue = "69835")] -pub unsafe fn size_of_val_raw(val: *const T) -> usize { +#[rustc_const_unstable(feature = "const_size_of_val_raw", issue = "46571")] +pub const unsafe fn size_of_val_raw(val: *const T) -> usize { intrinsics::size_of_val(val) } @@ -505,7 +506,8 @@ pub const fn align_of_val(val: &T) -> usize { /// ``` #[inline] #[unstable(feature = "layout_for_ptr", issue = "69835")] -pub unsafe fn align_of_val_raw(val: *const T) -> usize { +#[rustc_const_unstable(feature = "const_align_of_val_raw", issue = "46571")] +pub const unsafe fn align_of_val_raw(val: *const T) -> usize { intrinsics::min_align_of_val(val) } diff --git a/src/test/ui/consts/const-size_of_val-align_of_val.rs b/src/test/ui/consts/const-size_of_val-align_of_val.rs index e8e6f1d3900..5c0d7d94d64 100644 --- a/src/test/ui/consts/const-size_of_val-align_of_val.rs +++ b/src/test/ui/consts/const-size_of_val-align_of_val.rs @@ -1,6 +1,7 @@ // run-pass #![feature(const_size_of_val, const_align_of_val)] +#![feature(const_size_of_val_raw, const_align_of_val_raw, layout_for_ptr)] use std::mem; @@ -32,6 +33,9 @@ const ALIGN_OF_UGH: usize = mem::align_of_val(&UGH); const SIZE_OF_SLICE: usize = mem::size_of_val("foobar".as_bytes()); +const SIZE_OF_DANGLING: usize = unsafe { mem::size_of_val_raw(0x100 as *const i32) }; +const ALIGN_OF_DANGLING: usize = unsafe { mem::align_of_val_raw(0x100 as *const i16) }; + fn main() { assert_eq!(SIZE_OF_FOO, mem::size_of::()); assert_eq!(SIZE_OF_BAR, mem::size_of::()); @@ -41,5 +45,8 @@ fn main() { assert_eq!(ALIGN_OF_BAR, mem::align_of::()); assert_eq!(ALIGN_OF_UGH, mem::align_of::()); + assert_eq!(SIZE_OF_DANGLING, mem::size_of::()); + assert_eq!(ALIGN_OF_DANGLING, mem::align_of::()); + assert_eq!(SIZE_OF_SLICE, "foobar".len()); }