Miri: let machine hook dynamically decide about alignment checks

diff --git a/src/librustc_mir/const_eval/machine.rs b/src/librustc_mir/const_eval/machine.rs
index e92634714789495b383426a3d58b654235544f9d..3f9aa9ed02d2aeee76907cf7f94bed3032b7478b 100644 (file)
--- a/src/librustc_mir/const_eval/machine.rs
+++ b/src/librustc_mir/const_eval/machine.rs
@@ -179,9 +179,12 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter {
 
     const GLOBAL_KIND: Option<!> = None; // no copying of globals from `tcx` to machine memory
 
-    // We do not check for alignment to avoid having to carry an `Align`
-    // in `ConstValue::ByRef`.
-    const CHECK_ALIGN: bool = false;
+    #[inline(always)]
+    fn enforce_alignment(_memory_extra: &Self::MemoryExtra) -> bool {
+        // We do not check for alignment to avoid having to carry an `Align`
+        // in `ConstValue::ByRef`.
+        false
+    }
 
     #[inline(always)]
     fn enforce_validity(_ecx: &InterpCx<'mir, 'tcx, Self>) -> bool {

diff --git a/src/librustc_mir/interpret/machine.rs b/src/librustc_mir/interpret/machine.rs
index fd67b088c93cff162b2f5363e9aa4936e6924619..dd3803eb96255ed41181a278f949f48c145d1f6c 100644 (file)
--- a/src/librustc_mir/interpret/machine.rs
+++ b/src/librustc_mir/interpret/machine.rs
@@ -118,7 +118,7 @@ pub trait Machine<'mir, 'tcx>: Sized {
     const GLOBAL_KIND: Option<Self::MemoryKind>;
 
     /// Whether memory accesses should be alignment-checked.
-    const CHECK_ALIGN: bool;
+    fn enforce_alignment(memory_extra: &Self::MemoryExtra) -> bool;
 
     /// Whether to enforce the validity invariant
     fn enforce_validity(ecx: &InterpCx<'mir, 'tcx, Self>) -> bool;

diff --git a/src/librustc_mir/interpret/memory.rs b/src/librustc_mir/interpret/memory.rs
index 539537e9de80c414fe6b19d8622466fe5d3c510d..bcad7855c373690963870560eda95850fdee620e 100644 (file)
--- a/src/librustc_mir/interpret/memory.rs
+++ b/src/librustc_mir/interpret/memory.rs
@@ -323,12 +323,12 @@ pub fn check_ptr_access(
         size: Size,
         align: Align,
     ) -> InterpResult<'tcx, Option<Pointer<M::PointerTag>>> {
-        let align = M::CHECK_ALIGN.then_some(align);
+        let align = M::enforce_alignment(&self.extra).then_some(align);
         self.check_ptr_access_align(sptr, size, align, CheckInAllocMsg::MemoryAccessTest)
     }
 
     /// Like `check_ptr_access`, but *definitely* checks alignment when `align`
-    /// is `Some` (overriding `M::CHECK_ALIGN`). Also lets the caller control
+    /// is `Some` (overriding `M::enforce_alignment`). Also lets the caller control
     /// the error message for the out-of-bounds case.
     pub fn check_ptr_access_align(
         &self,

diff --git a/src/librustc_mir/transform/const_prop.rs b/src/librustc_mir/transform/const_prop.rs
index 5a00f206a7646892463e56a32264fda2c7cc1ed6..9a6d5ab34a5ace5b5f3b6e7a7b86a7333f8b0100 100644 (file)
--- a/src/librustc_mir/transform/const_prop.rs
+++ b/src/librustc_mir/transform/const_prop.rs
@@ -173,7 +173,10 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for ConstPropMachine {
 
     const GLOBAL_KIND: Option<!> = None; // no copying of globals from `tcx` to machine memory
 
-    const CHECK_ALIGN: bool = false;
+    #[inline(always)]
+    fn enforce_alignment(_memory_extra: &Self::MemoryExtra) -> bool {
+        false
+    }
 
     #[inline(always)]
     fn enforce_validity(_ecx: &InterpCx<'mir, 'tcx, Self>) -> bool {