Add const eval test

Author: Centri3

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

@@ -149,7 +149,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
             // Would not be considered UB, or the other way around (`is_val_statically_known(0)`).
             "is_val_statically_known" => {
                 let [_] = check_arg_count(args)?;
-                let branch = this.machine.rng.get_mut().gen();
+                let branch: bool = this.machine.rng.get_mut().gen();
                 this.write_scalar(Scalar::from_bool(branch), dest)?;
             }
 
@@ -477,11 +477,10 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
                 }
             }
             // Nothing else
-            _ =>
-                span_bug!(
-                    this.cur_span(),
-                    "`float_to_int_unchecked` called with non-int output type {dest_ty:?}"
-                ),
+            _ => span_bug!(
+                this.cur_span(),
+                "`float_to_int_unchecked` called with non-int output type {dest_ty:?}"
+            ),
         })
     }
 >>>>>>> acbf90a9489 (Make MIRI choose the path randomly and rename the intrinsic)

src/tools/miri/tests/pass/intrinsics.rs

@@ -33,11 +33,20 @@ fn main() {
     assert_eq!(intrinsics::likely(false), false);
     assert_eq!(intrinsics::unlikely(true), true);
 
-    if unsafe { intrinsics::is_val_statically_known(&0 as _) } {
-        0
-    } else {
-        0
-    };
+    let mut saw_true = false;
+    let mut saw_false = false;
+
+    for _ in 0..50 {
+        if unsafe { intrinsics::is_val_statically_known(0) } {
+            saw_true = true;
+        } else {
+            saw_false = true;
+        }
+    }
+    assert!(
+        saw_true && saw_false,
+        "`is_val_statically_known` failed to return both true and false. Congrats, you won the lottery!"
+    );
 
     intrinsics::forget(Bomb);
 

tests/codegen/is_val_statically_known.rs

@@ -1,4 +1,7 @@
-// compile-flags: --crate-type=lib
+// #[cfg(bootstrap)]
+// ignore-stage1
+// compile-flags: --crate-type=lib -Zmerge-functions=disabled
+
 #![feature(core_intrinsics)]
 
 use std::intrinsics::is_val_statically_known;

tests/codegen/pow_of_two.rs

@@ -1,4 +1,6 @@
-// compile-flags: --crate-type=lib
+// #[cfg(bootstrap)]
+// ignore-stage1
+// compile-flags: --crate-type=lib -Zmerge-functions=disabled
 
 // CHECK-LABEL: @a(
 #[no_mangle]
@@ -10,9 +12,12 @@ pub fn a(exp: u32) -> u64 {
     2u64.pow(exp)
 }
 
-// This is sometimes an alias to `a`, but this isn't guaranteed
 #[no_mangle]
 pub fn b(exp: u32) -> i64 {
+    // CHECK: %[[R:.+]] = and i32 %exp, 63
+    // CHECK: %[[R:.+]] = zext i32 %[[R:.+]] to i64
+    // CHECK: %[[R:.+]] = shl nuw i64 %[[R:.+]].i, %[[R:.+]]
+    // CHECK: ret i64 %[[R:.+]]
     2i64.pow(exp)
 }
 

tests/ui/consts/is_val_statically_known.rs

@@ -0,0 +1,14 @@
+// run-pass
+
+#![feature(core_intrinsics)]
+#![feature(is_val_statically_known)]
+
+use std::intrinsics::is_val_statically_known;
+
+const CONST_TEST: bool = unsafe { is_val_statically_known(0) };
+
+fn main() {
+    if CONST_TEST {
+        unreachable!("guaranteed to return false during const eval");
+    }
+}