const eval: respect target.min_global_align

Author: folkertdev

compiler/rustc_const_eval/src/interpret/memory.rs

@@ -893,7 +893,10 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
 
         // # Global allocations
         if let Some(global_alloc) = self.tcx.try_get_global_alloc(id) {
-            let (size, align) = global_alloc.size_and_align(*self.tcx, self.typing_env);
+            let (size, mut align) = global_alloc.size_and_align(*self.tcx, self.typing_env);
+            if let Some(min_global_align) = self.tcx.sess.target.min_global_align {
+                align = Ord::max(align, min_global_align);
+            }
             let mutbl = global_alloc.mutability(*self.tcx, self.typing_env);
             let kind = match global_alloc {
                 GlobalAlloc::Static { .. } | GlobalAlloc::Memory { .. } => AllocKind::LiveData,

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

@@ -0,0 +1,52 @@
+// Test that miri respects the `target.min_global_align` value for the target.
+//
+// The only way to observe its effect currently is to test for the alignment of statics with a
+// natural alignment of 1 on s390x. On that target, the `min_global_align` is 2 bytes.
+
+static T0: bool = true;
+static T1: bool = true;
+static T2: bool = true;
+static T3: bool = true;
+static T4: bool = true;
+static T5: bool = true;
+static T6: bool = true;
+static T7: bool = true;
+static T8: bool = true;
+static T9: bool = true;
+
+static F0: bool = false;
+static F1: bool = false;
+static F2: bool = false;
+static F3: bool = false;
+static F4: bool = false;
+static F5: bool = false;
+static F6: bool = false;
+static F7: bool = false;
+static F8: bool = false;
+static F9: bool = false;
+
+fn main() {
+    let min_align = if cfg!(target_arch = "s390x") { 2 } else { 1 };
+
+    assert!(((&T0) as *const bool).addr().is_multiple_of(min_align));
+    assert!(((&T1) as *const bool).addr().is_multiple_of(min_align));
+    assert!(((&T2) as *const bool).addr().is_multiple_of(min_align));
+    assert!(((&T3) as *const bool).addr().is_multiple_of(min_align));
+    assert!(((&T4) as *const bool).addr().is_multiple_of(min_align));
+    assert!(((&T5) as *const bool).addr().is_multiple_of(min_align));
+    assert!(((&T6) as *const bool).addr().is_multiple_of(min_align));
+    assert!(((&T7) as *const bool).addr().is_multiple_of(min_align));
+    assert!(((&T8) as *const bool).addr().is_multiple_of(min_align));
+    assert!(((&T9) as *const bool).addr().is_multiple_of(min_align));
+
+    assert!(((&F0) as *const bool).addr().is_multiple_of(min_align));
+    assert!(((&F1) as *const bool).addr().is_multiple_of(min_align));
+    assert!(((&F2) as *const bool).addr().is_multiple_of(min_align));
+    assert!(((&F3) as *const bool).addr().is_multiple_of(min_align));
+    assert!(((&F4) as *const bool).addr().is_multiple_of(min_align));
+    assert!(((&F5) as *const bool).addr().is_multiple_of(min_align));
+    assert!(((&F6) as *const bool).addr().is_multiple_of(min_align));
+    assert!(((&F7) as *const bool).addr().is_multiple_of(min_align));
+    assert!(((&F8) as *const bool).addr().is_multiple_of(min_align));
+    assert!(((&F9) as *const bool).addr().is_multiple_of(min_align));
+}