portable SIMD: add rem intrinsic; test div and rem intrinsic UB

Author: RalfJung

src/shims/intrinsics.rs

@@ -306,7 +306,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
             }
 
             // SIMD operations
-            "simd_add" | "simd_sub" | "simd_mul" | "simd_div" => {
+            "simd_add" | "simd_sub" | "simd_mul" | "simd_div" | "simd_rem" => {
                 let &[ref left, ref right] = check_arg_count(args)?;
                 let (left, left_len) = this.operand_to_simd(left)?;
                 let (right, right_len) = this.operand_to_simd(right)?;
@@ -320,6 +320,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
                     "simd_sub" => mir::BinOp::Sub,
                     "simd_mul" => mir::BinOp::Mul,
                     "simd_div" => mir::BinOp::Div,
+                    "simd_rem" => mir::BinOp::Rem,
                     _ => unreachable!(),
                 };
 

tests/compile-fail/intrinsics/div-by-zero-1.rs renamed to tests/compile-fail/intrinsics/div-by-zero.rs

@@ -0,0 +1,15 @@
+#![feature(platform_intrinsics, repr_simd)]
+
+extern "platform-intrinsic" {
+    pub(crate) fn simd_div<T>(x: T, y: T) -> T;
+}
+
+#[repr(simd)]
+#[allow(non_camel_case_types)]
+struct i32x2(i32, i32);
+
+fn main() { unsafe {
+    let x = i32x2(1, 1);
+    let y = i32x2(1, 0);
+    simd_div(x, y); //~ERROR Undefined Behavior: dividing by zero
+} }

tests/compile-fail/intrinsics/div-by-zero-2.rs renamed to tests/compile-fail/intrinsics/rem-by-zero.rs

@@ -0,0 +1,15 @@
+#![feature(platform_intrinsics, repr_simd)]
+
+extern "platform-intrinsic" {
+    pub(crate) fn simd_rem<T>(x: T, y: T) -> T;
+}
+
+#[repr(simd)]
+#[allow(non_camel_case_types)]
+struct i32x2(i32, i32);
+
+fn main() { unsafe {
+    let x = i32x2(1, 1);
+    let y = i32x2(1, 0);
+    simd_rem(x, y); //~ERROR Undefined Behavior: calculating the remainder with a divisor of zero
+} }

tests/compile-fail/intrinsics/simd-div-by-zero.rs

@@ -9,6 +9,7 @@ fn simd_ops_f32() {
     assert_eq!(a * b, f32x4::from_array([10.0, 20.0, 30.0, 40.0]));
     assert_eq!(b / a, f32x4::from_array([0.1, 0.2, 0.3, 0.4]));
     assert_eq!(a / 2.0, f32x4::splat(5.0));
+    assert_eq!(a % b, f32x4::from_array([0.0, 0.0, 1.0, 2.0]));
 }
 
 fn simd_ops_i32() {
@@ -19,6 +20,7 @@ fn simd_ops_i32() {
     assert_eq!(a * b, i32x4::from_array([10, 20, 30, 40]));
     assert_eq!(a / b, i32x4::from_array([10, 5, 3, 2]));
     assert_eq!(a / 2, i32x4::splat(5));
+    assert_eq!(a % b, i32x4::from_array([0, 0, 1, 2]));
 }
 
 fn main() {