Give the assume intrinsic a fallback body

oli-obk · oli-obk · commit 6a671bdbf1c0 · 2024-02-16T22:24:50.000Z
diff --git a/compiler/rustc_hir_analysis/src/check/intrinsic.rs b/compiler/rustc_hir_analysis/src/check/intrinsic.rs
@@ -407,7 +407,7 @@ pub fn check_intrinsic_type(
             }
             sym::float_to_int_unchecked => (2, 0, vec![param(0)], param(1)),
 
-            sym::assume => (0, 0, vec![tcx.types.bool], Ty::new_unit(tcx)),
+            sym::assume => (0, 1, vec![tcx.types.bool], Ty::new_unit(tcx)),
             sym::likely => (0, 0, vec![tcx.types.bool], tcx.types.bool),
             sym::unlikely => (0, 0, vec![tcx.types.bool], tcx.types.bool),
 
diff --git a/library/core/src/intrinsics.rs b/library/core/src/intrinsics.rs
@@ -937,20 +937,30 @@ extern "rust-intrinsic" {
     #[rustc_nounwind]
     pub fn unreachable() -> !;
 
-    /// Informs the optimizer that a condition is always true.
-    /// If the condition is false, the behavior is undefined.
-    ///
-    /// No code is generated for this intrinsic, but the optimizer will try
-    /// to preserve it (and its condition) between passes, which may interfere
-    /// with optimization of surrounding code and reduce performance. It should
-    /// not be used if the invariant can be discovered by the optimizer on its
-    /// own, or if it does not enable any significant optimizations.
-    ///
-    /// This intrinsic does not have a stable counterpart.
-    #[rustc_const_stable(feature = "const_assume", since = "1.77.0")]
-    #[rustc_nounwind]
-    pub fn assume(b: bool);
+}
+
+/// Informs the optimizer that a condition is always true.
+/// If the condition is false, the behavior is undefined.
+///
+/// No code is generated for this intrinsic, but the optimizer will try
+/// to preserve it (and its condition) between passes, which may interfere
+/// with optimization of surrounding code and reduce performance. It should
+/// not be used if the invariant can be discovered by the optimizer on its
+/// own, or if it does not enable any significant optimizations.
+///
+/// This intrinsic does not have a stable counterpart.
+#[rustc_const_stable(feature = "const_assume", since = "1.77.0")]
+#[rustc_nounwind]
+#[unstable(feature = "core_intrinsics", issue = "none")]
+#[cfg_attr(not(bootstrap), rustc_intrinsic)]
+pub const unsafe fn assume(b: bool) {
+    if !b {
+        // SAFETY: the caller must guarantee the argument is never `false`
+        unsafe { unreachable() }
+    }
+}
 
+extern "rust-intrinsic" {
     /// Hints to the compiler that branch condition is likely to be true.
     /// Returns the value passed to it.
     ///

Original file line number	Diff line number	Diff line change
`@@ -407,7 +407,7 @@ pub fn check_intrinsic_type(`
`407`	`407`	`}`
`408`	`408`	`sym::float_to_int_unchecked => (2, 0, vec![param(0)], param(1)),`
`409`	`409`
`410`		`- sym::assume => (0, 0, vec![tcx.types.bool], Ty::new_unit(tcx)),`
	`410`	`+ sym::assume => (0, 1, vec![tcx.types.bool], Ty::new_unit(tcx)),`
`411`	`411`	`sym::likely => (0, 0, vec![tcx.types.bool], tcx.types.bool),`
`412`	`412`	`sym::unlikely => (0, 0, vec![tcx.types.bool], tcx.types.bool),`
`413`	`413`