implement SIMD ptr casts

Author: RalfJung

src/tools/miri/src/shims/intrinsics/simd.rs

@@ -421,34 +421,50 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
  }
  }
  #[rustfmt::skip]
- "cast" | "as" => {
+ "cast" | "as" | "cast_ptr" | "expose_addr" | "from_exposed_addr" => {
  let [op] = check_arg_count(args)?;
  let (op, op_len) = this.operand_to_simd(op)?;
  let (dest, dest_len) = this.place_to_simd(dest)?;
 
  assert_eq!(dest_len, op_len);
 
+ let unsafe_cast = intrinsic_name == "cast";
  let safe_cast = intrinsic_name == "as";
+ let ptr_cast = intrinsic_name == "cast_ptr";
+ let expose_cast = intrinsic_name == "expose_addr";
+ let from_exposed_cast = intrinsic_name == "from_exposed_addr";
 
  for i in 0..dest_len {
  let op = this.read_immediate(&this.mplace_index(&op, i)?.into())?;
  let dest = this.mplace_index(&dest, i)?;
 
  let val = match (op.layout.ty.kind(), dest.layout.ty.kind()) {
  // Int-to-(int|float): always safe
- (ty::Int(_) | ty::Uint(_), ty::Int(_) | ty::Uint(_) | ty::Float(_)) =>
+ (ty::Int(_) | ty::Uint(_), ty::Int(_) | ty::Uint(_) | ty::Float(_)) if safe_cast || unsafe_cast =>
  this.int_to_int_or_float(&op, dest.layout.ty)?,
  // Float-to-float: always safe
- (ty::Float(_), ty::Float(_)) =>
+ (ty::Float(_), ty::Float(_)) if safe_cast || unsafe_cast =>
  this.float_to_float_or_int(&op, dest.layout.ty)?,
  // Float-to-int in safe mode
  (ty::Float(_), ty::Int(_) | ty::Uint(_)) if safe_cast =>
  this.float_to_float_or_int(&op, dest.layout.ty)?,
  // Float-to-int in unchecked mode
- (ty::Float(FloatTy::F32), ty::Int(_) | ty::Uint(_)) if !safe_cast =>
+ (ty::Float(FloatTy::F32), ty::Int(_) | ty::Uint(_)) if unsafe_cast =>
  this.float_to_int_unchecked(op.to_scalar().to_f32()?, dest.layout.ty)?.into(),
- (ty::Float(FloatTy::F64), ty::Int(_) | ty::Uint(_)) if !safe_cast =>
+ (ty::Float(FloatTy::F64), ty::Int(_) | ty::Uint(_)) if unsafe_cast =>
  this.float_to_int_unchecked(op.to_scalar().to_f64()?, dest.layout.ty)?.into(),
+ // Ptr-to-ptr cast
+ (ty::RawPtr(..), ty::RawPtr(..)) if ptr_cast => {
+ this.ptr_to_ptr(&op, dest.layout.ty)?
+ }
+ // Ptr/Int casts
+ (ty::RawPtr(..), ty::Int(_) | ty::Uint(_)) if expose_cast => {
+ this.pointer_expose_address_cast(&op, dest.layout.ty)?
+ }
+ (ty::Int(_) | ty::Uint(_), ty::RawPtr(..)) if from_exposed_cast => {
+ this.pointer_from_exposed_address_cast(&op, dest.layout.ty)?
+ }
+ // Error otherwise
  _ =>
  throw_unsup_format!(
  "Unsupported SIMD cast from element type {from_ty} to {to_ty}",

src/tools/miri/tests/pass/portable-simd-ptrs.rs

@@ -0,0 +1,12 @@
+// Separate test without strict provenance
+//@compile-flags: -Zmiri-permissive-provenance
+#![feature(portable_simd, platform_intrinsics)]
+use std::ptr;
+use std::simd::*;
+
+fn main() {
+ // Pointer casts
+ let _val: Simd<*const u8, 4> = Simd::<*const i32, 4>::splat(ptr::null()).cast_ptr();
+ let addrs = Simd::<*const i32, 4>::splat(ptr::null()).expose_addr();
+ let _ptrs = Simd::<*const i32, 4>::from_exposed_addr(addrs);
+}