diff options
Diffstat (limited to 'third_party/rust/encoding_rs/src/mem.rs')
| -rw-r--r-- | third_party/rust/encoding_rs/src/mem.rs | 18 |
1 files changed, 16 insertions, 2 deletions
diff --git a/third_party/rust/encoding_rs/src/mem.rs b/third_party/rust/encoding_rs/src/mem.rs index ba8d9e3f4c..0f9f3c1977 100644 --- a/third_party/rust/encoding_rs/src/mem.rs +++ b/third_party/rust/encoding_rs/src/mem.rs @@ -116,6 +116,11 @@ macro_rules! by_unit_check_alu { } let len_minus_stride = len - ALU_ALIGNMENT / unit_size; if offset + (4 * (ALU_ALIGNMENT / unit_size)) <= len { + // Safety: the above check lets us perform 4 consecutive reads of + // length ALU_ALIGNMENT / unit_size. ALU_ALIGNMENT is the size of usize, and unit_size + // is the size of the `src` pointer, so this is equal to performing four usize reads. + // + // This invariant is upheld on all loop iterations let len_minus_unroll = len - (4 * (ALU_ALIGNMENT / unit_size)); loop { let unroll_accu = unsafe { *(src.add(offset) as *const usize) } @@ -134,12 +139,14 @@ macro_rules! by_unit_check_alu { return false; } offset += 4 * (ALU_ALIGNMENT / unit_size); + // Safety: this check lets us continue to perform the 4 reads earlier if offset > len_minus_unroll { break; } } } while offset <= len_minus_stride { + // Safety: the above check lets us perform one usize read. accu |= unsafe { *(src.add(offset) as *const usize) }; offset += ALU_ALIGNMENT / unit_size; } @@ -189,6 +196,11 @@ macro_rules! by_unit_check_simd { } let len_minus_stride = len - SIMD_STRIDE_SIZE / unit_size; if offset + (4 * (SIMD_STRIDE_SIZE / unit_size)) <= len { + // Safety: the above check lets us perform 4 consecutive reads of + // length SIMD_STRIDE_SIZE / unit_size. SIMD_STRIDE_SIZE is the size of $simd_ty, and unit_size + // is the size of the `src` pointer, so this is equal to performing four $simd_ty reads. + // + // This invariant is upheld on all loop iterations let len_minus_unroll = len - (4 * (SIMD_STRIDE_SIZE / unit_size)); loop { let unroll_accu = unsafe { *(src.add(offset) as *const $simd_ty) } @@ -208,6 +220,7 @@ macro_rules! by_unit_check_simd { return false; } offset += 4 * (SIMD_STRIDE_SIZE / unit_size); + // Safety: this check lets us continue to perform the 4 reads earlier if offset > len_minus_unroll { break; } @@ -215,6 +228,7 @@ macro_rules! by_unit_check_simd { } let mut simd_accu = $splat; while offset <= len_minus_stride { + // Safety: the above check lets us perform one $simd_ty read. simd_accu = simd_accu | unsafe { *(src.add(offset) as *const $simd_ty) }; offset += SIMD_STRIDE_SIZE / unit_size; } @@ -234,8 +248,8 @@ macro_rules! by_unit_check_simd { cfg_if! { if #[cfg(all(feature = "simd-accel", any(target_feature = "sse2", all(target_endian = "little", target_arch = "aarch64"), all(target_endian = "little", target_feature = "neon"))))] { use crate::simd_funcs::*; - use packed_simd::u8x16; - use packed_simd::u16x8; + use core::simd::u8x16; + use core::simd::u16x8; const SIMD_ALIGNMENT: usize = 16; |