diff options
| -rw-r--r-- | src/tools/miri/src/helpers.rs | 20 | ||||
| -rw-r--r-- | src/tools/miri/src/shims/x86/sse2.rs | 74 |
2 files changed, 54 insertions, 40 deletions
diff --git a/src/tools/miri/src/helpers.rs b/src/tools/miri/src/helpers.rs index 7805fe25bcd..bbd905be0a9 100644 --- a/src/tools/miri/src/helpers.rs +++ b/src/tools/miri/src/helpers.rs @@ -14,7 +14,7 @@ use rustc_middle::mir; use rustc_middle::ty::{ self, layout::{IntegerExt as _, LayoutOf, TyAndLayout}, - Ty, TyCtxt, + IntTy, Ty, TyCtxt, UintTy, }; use rustc_span::{def_id::CrateNum, sym, Span, Symbol}; use rustc_target::abi::{Align, FieldIdx, FieldsShape, Integer, Size, Variants}; @@ -1067,6 +1067,24 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> { ), } } + + /// Returns an integer type that is twice wide as `ty` + fn get_twice_wide_int_ty(&self, ty: Ty<'tcx>) -> Ty<'tcx> { + let this = self.eval_context_ref(); + match ty.kind() { + // Unsigned + ty::Uint(UintTy::U8) => this.tcx.types.u16, + ty::Uint(UintTy::U16) => this.tcx.types.u32, + ty::Uint(UintTy::U32) => this.tcx.types.u64, + ty::Uint(UintTy::U64) => this.tcx.types.u128, + // Signed + ty::Int(IntTy::I8) => this.tcx.types.i16, + ty::Int(IntTy::I16) => this.tcx.types.i32, + ty::Int(IntTy::I32) => this.tcx.types.i64, + ty::Int(IntTy::I64) => this.tcx.types.i128, + _ => span_bug!(this.cur_span(), "unexpected type: {ty:?}"), + } + } } impl<'mir, 'tcx> MiriMachine<'mir, 'tcx> { diff --git a/src/tools/miri/src/shims/x86/sse2.rs b/src/tools/miri/src/shims/x86/sse2.rs index 098409d6e35..28aebc8cba8 100644 --- a/src/tools/miri/src/shims/x86/sse2.rs +++ b/src/tools/miri/src/shims/x86/sse2.rs @@ -2,6 +2,7 @@ use rustc_apfloat::{ ieee::{Double, Single}, Float as _, }; +use rustc_middle::mir; use rustc_middle::ty::layout::LayoutOf as _; use rustc_middle::ty::Ty; use rustc_span::Symbol; @@ -36,9 +37,9 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> { // Intrinsincs sufixed with "epiX" or "epuX" operate with X-bit signed or unsigned // vectors. match unprefixed_name { - // Used to implement the _mm_avg_epu8 function. - // Averages packed unsigned 8-bit integers in `left` and `right`. - "pavg.b" => { + // Used to implement the _mm_avg_epu8 and _mm_avg_epu16 functions. + // Averages packed unsigned 8/16-bit integers in `left` and `right`. + "pavg.b" | "pavg.w" => { let [left, right] = this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?; @@ -50,46 +51,41 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> { assert_eq!(dest_len, right_len); for i in 0..dest_len { - let left = this.read_scalar(&this.project_index(&left, i)?)?.to_u8()?; - let right = this.read_scalar(&this.project_index(&right, i)?)?.to_u8()?; + let left = this.read_immediate(&this.project_index(&left, i)?)?; + let right = this.read_immediate(&this.project_index(&right, i)?)?; let dest = this.project_index(&dest, i)?; - // Values are expanded from u8 to u16, so adds cannot overflow. - let res = u16::from(left) - .checked_add(u16::from(right)) - .unwrap() - .checked_add(1) - .unwrap() - / 2; - this.write_scalar(Scalar::from_u8(res.try_into().unwrap()), &dest)?; - } - } - // Used to implement the _mm_avg_epu16 function. - // Averages packed unsigned 16-bit integers in `left` and `right`. - "pavg.w" => { - let [left, right] = - this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?; - - let (left, left_len) = this.operand_to_simd(left)?; - let (right, right_len) = this.operand_to_simd(right)?; - let (dest, dest_len) = this.place_to_simd(dest)?; - - assert_eq!(dest_len, left_len); - assert_eq!(dest_len, right_len); + // Widen the operands to avoid overflow + let twice_wide_ty = this.get_twice_wide_int_ty(left.layout.ty); + let twice_wide_layout = this.layout_of(twice_wide_ty)?; + let left = this.int_to_int_or_float(&left, twice_wide_ty)?; + let right = this.int_to_int_or_float(&right, twice_wide_ty)?; + + // Calculate left + right + 1 + let (added, _overflow, _ty) = this.overflowing_binary_op( + mir::BinOp::Add, + &ImmTy::from_immediate(left, twice_wide_layout), + &ImmTy::from_immediate(right, twice_wide_layout), + )?; + let (added, _overflow, _ty) = this.overflowing_binary_op( + mir::BinOp::Add, + &ImmTy::from_scalar(added, twice_wide_layout), + &ImmTy::from_uint(1u32, twice_wide_layout), + )?; - for i in 0..dest_len { - let left = this.read_scalar(&this.project_index(&left, i)?)?.to_u16()?; - let right = this.read_scalar(&this.project_index(&right, i)?)?.to_u16()?; - let dest = this.project_index(&dest, i)?; + // Calculate (left + right + 1) / 2 + let (divided, _overflow, _ty) = this.overflowing_binary_op( + mir::BinOp::Div, + &ImmTy::from_scalar(added, twice_wide_layout), + &ImmTy::from_uint(2u32, twice_wide_layout), + )?; - // Values are expanded from u16 to u32, so adds cannot overflow. - let res = u32::from(left) - .checked_add(u32::from(right)) - .unwrap() - .checked_add(1) - .unwrap() - / 2; - this.write_scalar(Scalar::from_u16(res.try_into().unwrap()), &dest)?; + // Narrow back to the original type + let res = this.int_to_int_or_float( + &ImmTy::from_scalar(divided, twice_wide_layout), + dest.layout.ty, + )?; + this.write_immediate(res, &dest)?; } } // Used to implement the _mm_mulhi_epi16 function. |