Auto merge of #113720 - eduardosm:miri-target-feature, r=RalfJung,oli-obk

miri: fail when calling a function that requires an unavailable target feature

miri will report an UB when calling a function that has a `#[target_feature(enable = ...)]` attribute is called and the required feature is not available.

"Available features" are the same that `is_x86_feature_detected!` (or equivalent) reports to be available during miri execution (which can be enabled or disabled with the `-C target-feature` flag).

compiler/rustc_const_eval/messages.ftl

@@ -399,6 +399,9 @@ const_eval_unallowed_mutable_refs_raw =
 const_eval_unallowed_op_in_const_context =
     {$msg}
 
+const_eval_unavailable_target_features_for_fn =
+    calling a function that requires unavailable target features: {$unavailable_feats}
+
 const_eval_undefined_behavior =
     it is undefined behavior to use this value
 

compiler/rustc_const_eval/src/interpret/terminator.rs

@@ -503,6 +503,11 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                     }
                 }
 
+                // Check that all target features required by the callee (i.e., from
+                // the attribute `#[target_feature(enable = ...)]`) are enabled at
+                // compile time.
+                self.check_fn_target_features(instance)?;
+
                 if !callee_fn_abi.can_unwind {
                     // The callee cannot unwind, so force the `Unreachable` unwind handling.
                     unwind = mir::UnwindAction::Unreachable;
@@ -786,6 +791,31 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         }
     }
 
+    fn check_fn_target_features(&self, instance: ty::Instance<'tcx>) -> InterpResult<'tcx, ()> {
+        let attrs = self.tcx.codegen_fn_attrs(instance.def_id());
+        if attrs
+            .target_features
+            .iter()
+            .any(|feature| !self.tcx.sess.target_features.contains(feature))
+        {
+            throw_ub_custom!(
+                fluent::const_eval_unavailable_target_features_for_fn,
+                unavailable_feats = attrs
+                    .target_features
+                    .iter()
+                    .filter(|&feature| !self.tcx.sess.target_features.contains(feature))
+                    .fold(String::new(), |mut s, feature| {
+                        if !s.is_empty() {
+                            s.push_str(", ");
+                        }
+                        s.push_str(feature.as_str());
+                        s
+                    }),
+            );
+        }
+        Ok(())
+    }
+
     fn drop_in_place(
         &mut self,
         place: &PlaceTy<'tcx, M::Provenance>,

src/tools/miri/tests/fail/function_calls/target_feature.rs

@@ -0,0 +1,11 @@
+//@only-target-x86_64: uses x86 target features
+
+fn main() {
+    assert!(!is_x86_feature_detected!("ssse3"));
+    unsafe {
+        ssse3_fn(); //~ ERROR: calling a function that requires unavailable target features: ssse3
+    }
+}
+
+#[target_feature(enable = "ssse3")]
+unsafe fn ssse3_fn() {}

src/tools/miri/tests/fail/function_calls/target_feature.stderr

@@ -0,0 +1,15 @@
+error: Undefined Behavior: calling a function that requires unavailable target features: ssse3
+  --> $DIR/target_feature.rs:LL:CC
+   |
+LL |         ssse3_fn();
+   |         ^^^^^^^^^^ calling a function that requires unavailable target features: ssse3
+   |
+   = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
+   = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
+   = note: BACKTRACE:
+   = note: inside `main` at $DIR/target_feature.rs:LL:CC
+
+note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
+
+error: aborting due to previous error
+

src/tools/miri/tests/pass/function_calls/target_feature.rs

@@ -0,0 +1,12 @@
+//@only-target-x86_64: uses x86 target features
+//@compile-flags: -C target-feature=+ssse3
+
+fn main() {
+    assert!(is_x86_feature_detected!("ssse3"));
+    unsafe {
+        ssse3_fn();
+    }
+}
+
+#[target_feature(enable = "ssse3")]
+unsafe fn ssse3_fn() {}

tests/ui/consts/const-eval/const_fn_target_feature.rs

@@ -0,0 +1,17 @@
+// only-x86_64
+// compile-flags:-C target-feature=+ssse3
+
+#![crate_type = "lib"]
+
+// ok (ssse3 enabled at compile time)
+const A: () = unsafe { ssse3_fn() };
+
+// error (avx2 not enabled at compile time)
+const B: () = unsafe { avx2_fn() };
+//~^ ERROR evaluation of constant value failed
+
+#[target_feature(enable = "ssse3")]
+const unsafe fn ssse3_fn() {}
+
+#[target_feature(enable = "avx2")]
+const unsafe fn avx2_fn() {}

tests/ui/consts/const-eval/const_fn_target_feature.stderr

@@ -0,0 +1,9 @@
+error[E0080]: evaluation of constant value failed
+  --> $DIR/const_fn_target_feature.rs:10:24
+   |
+LL | const B: () = unsafe { avx2_fn() };
+   |                        ^^^^^^^^^ calling a function that requires unavailable target features: avx2
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0080`.