Move provenance checks out of interning method.

Author: cjgillot

compiler/rustc_const_eval/src/interpret/intern.rs

@@ -450,7 +450,7 @@ pub fn intern_const_alloc_recursive<
     Ok(())
 }
 
-/// Intern `ret`, checking it references no other allocation.
+/// Intern `ret`. This function assumes that `ret` references no other allocation.
 #[instrument(level = "debug", skip(ecx))]
 pub fn intern_const_alloc_for_constprop<
     'mir,
@@ -461,17 +461,7 @@ pub fn intern_const_alloc_for_constprop<
     ecx: &mut InterpCx<'mir, 'tcx, M>,
     ret: &MPlaceTy<'tcx>,
 ) -> InterpResult<'tcx, ()> {
-    let Some((size, align)) = ecx.size_and_align_of_mplace(ret)? else {
-        throw_inval!(ConstPropNonsense)
-    };
-
-    let alloc_ref = ecx.get_ptr_alloc(ret.ptr(), size, align)?.unwrap();
-    // Do not try interning a value that contains provenance.
-    if alloc_ref.has_provenance() {
-        throw_inval!(ConstPropNonsense)
-    }
-
-    // remove allocation
+    // Move allocation to `tcx`.
     let alloc_id = ret.ptr().provenance.unwrap();
     let Some((_, mut alloc)) = ecx.memory.alloc_map.remove(&alloc_id) else {
         // Pointer not found in local memory map. It is either a pointer to the global

compiler/rustc_const_eval/src/interpret/memory.rs

@@ -1021,7 +1021,7 @@ impl<'tcx, 'a, Prov: Provenance, Extra, Bytes: AllocBytes> AllocRef<'a, 'tcx, Pr
     }
 
     /// Returns whether the allocation has provenance anywhere in the range of the `AllocRef`.
-    pub(crate) fn has_provenance(&self) -> bool {
+    pub fn has_provenance(&self) -> bool {
         !self.alloc.provenance().range_empty(self.range, &self.tcx)
     }
 }

compiler/rustc_mir_transform/src/gvn.rs

@@ -832,6 +832,7 @@ fn op_to_prop_const<'tcx>(
     // If this constant has scalar ABI, return it as a `ConstValue::Scalar`.
     if let Abi::Scalar(abi::Scalar::Initialized { .. }) = op.layout.abi
         && let Ok(scalar) = ecx.read_scalar(op)
+        && scalar.try_to_int().is_ok()
     {
         return Some(ConstValue::Scalar(scalar));
     }
@@ -840,6 +841,14 @@ fn op_to_prop_const<'tcx>(
     if let Either::Left(mplace) = op.as_mplace_or_imm()
         && let MemPlaceMeta::None = mplace.meta()
     {
+        let (size, align) = ecx.size_and_align_of_mplace(&mplace).ok()??;
+
+        let alloc_ref = ecx.get_ptr_alloc(mplace.ptr(), size, align).ok()??;
+        // Do not try interning a value that contains provenance.
+        if alloc_ref.has_provenance() {
+            return None;
+        }
+
         intern_const_alloc_for_constprop(ecx, &mplace).ok()?;
         let pointer = mplace.ptr().into_pointer_or_addr().ok()?;
         let (alloc_id, offset) = pointer.into_parts();
@@ -853,7 +862,13 @@ fn op_to_prop_const<'tcx>(
     // Everything failed: create a new allocation to hold the data.
     let alloc_id =
         ecx.intern_with_temp_alloc(op.layout, |ecx, dest| ecx.copy_op(op, dest, false)).ok()?;
-    Some(ConstValue::Indirect { alloc_id, offset: Size::ZERO })
+    let value = ConstValue::Indirect { alloc_id, offset: Size::ZERO };
+
+    if !value.has_provenance(*ecx.tcx, op.layout.size) {
+        return Some(value);
+    }
+
+    None
 }
 
 impl<'tcx> VnState<'_, 'tcx> {
@@ -905,9 +920,7 @@ impl<'tcx> VnState<'_, 'tcx> {
 
         // Check that we do not leak a pointer.
         // Those pointers may lose part of their identity in codegen.
-        if value.has_provenance(self.tcx, op.layout.size) {
-            return None;
-        }
+        assert!(!value.has_provenance(self.tcx, op.layout.size));
 
         let const_ = Const::Val(value, op.layout.ty);
         Some(ConstOperand { span: rustc_span::DUMMY_SP, user_ty: None, const_ })