Introduce NullOp::AlignOf

nbdd0121 · nbdd0121 · commit bfa210e3e6d2 · 2021-09-07T16:48:09.000+01:00
diff --git a/compiler/rustc_codegen_ssa/src/mir/intrinsic.rs b/compiler/rustc_codegen_ssa/src/mir/intrinsic.rs
@@ -104,7 +104,6 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 }
             }
             sym::pref_align_of
-            | sym::min_align_of
             | sym::needs_drop
             | sym::type_id
             | sym::type_name
diff --git a/compiler/rustc_codegen_ssa/src/mir/rvalue.rs b/compiler/rustc_codegen_ssa/src/mir/rvalue.rs
@@ -501,6 +501,20 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 )
             }
 
+            mir::Rvalue::NullaryOp(mir::NullOp::AlignOf, ty) => {
+                let ty = self.monomorphize(ty);
+                assert!(bx.cx().type_is_sized(ty));
+                let val = bx.cx().const_usize(bx.cx().layout_of(ty).align.abi.bytes());
+                let tcx = self.cx.tcx();
+                (
+                    bx,
+                    OperandRef {
+                        val: OperandValue::Immediate(val),
+                        layout: self.cx.layout_of(tcx.types.usize),
+                    },
+                )
+            }
+
             mir::Rvalue::NullaryOp(mir::NullOp::Box, content_ty) => {
                 let content_ty = self.monomorphize(content_ty);
                 let content_layout = bx.cx().layout_of(content_ty);
diff --git a/compiler/rustc_middle/src/mir/mod.rs b/compiler/rustc_middle/src/mir/mod.rs
@@ -2252,6 +2252,8 @@ impl BinOp {
 pub enum NullOp {
     /// Returns the size of a value of that type
     SizeOf,
+    /// Returns the minimum alignment of a type
+    AlignOf,
     /// Creates a new uninitialized box for a value of that type
     Box,
 }
diff --git a/compiler/rustc_middle/src/mir/tcx.rs b/compiler/rustc_middle/src/mir/tcx.rs
@@ -196,7 +196,7 @@ impl<'tcx> Rvalue<'tcx> {
             Rvalue::UnaryOp(UnOp::Not | UnOp::Neg, ref operand) => operand.ty(local_decls, tcx),
             Rvalue::Discriminant(ref place) => place.ty(local_decls, tcx).ty.discriminant_ty(tcx),
             Rvalue::NullaryOp(NullOp::Box, t) => tcx.mk_box(t),
-            Rvalue::NullaryOp(NullOp::SizeOf, _) => tcx.types.usize,
+            Rvalue::NullaryOp(NullOp::SizeOf | NullOp::AlignOf, _) => tcx.types.usize,
             Rvalue::Aggregate(ref ak, ref ops) => match **ak {
                 AggregateKind::Array(ty) => tcx.mk_array(ty, ops.len() as u64),
                 AggregateKind::Tuple => tcx.mk_tup(ops.iter().map(|op| op.ty(local_decls, tcx))),
diff --git a/compiler/rustc_mir/src/dataflow/move_paths/builder.rs b/compiler/rustc_mir/src/dataflow/move_paths/builder.rs
@@ -343,7 +343,7 @@ impl<'b, 'a, 'tcx> Gatherer<'b, 'a, 'tcx> {
             | Rvalue::AddressOf(..)
             | Rvalue::Discriminant(..)
             | Rvalue::Len(..)
-            | Rvalue::NullaryOp(NullOp::SizeOf, _)
+            | Rvalue::NullaryOp(NullOp::SizeOf | NullOp::AlignOf, _)
             | Rvalue::NullaryOp(NullOp::Box, _) => {
                 // This returns an rvalue with uninitialized contents. We can't
                 // move out of it here because it is an rvalue - assignments always
diff --git a/compiler/rustc_mir/src/interpret/intrinsics.rs b/compiler/rustc_mir/src/interpret/intrinsics.rs
@@ -160,17 +160,14 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 self.write_scalar(Scalar::from_machine_usize(result, self), dest)?;
             }
 
-            sym::min_align_of
-            | sym::pref_align_of
+            sym::pref_align_of
             | sym::needs_drop
             | sym::type_id
             | sym::type_name
             | sym::variant_count => {
                 let gid = GlobalId { instance, promoted: None };
                 let ty = match intrinsic_name {
-                    sym::min_align_of | sym::pref_align_of | sym::variant_count => {
-                        self.tcx.types.usize
-                    }
+                    sym::pref_align_of | sym::variant_count => self.tcx.types.usize,
                     sym::needs_drop => self.tcx.types.bool,
                     sym::type_id => self.tcx.types.u64,
                     sym::type_name => self.tcx.mk_static_str(),
diff --git a/compiler/rustc_mir/src/interpret/step.rs b/compiler/rustc_mir/src/interpret/step.rs
@@ -284,6 +284,23 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 self.write_scalar(Scalar::from_machine_usize(layout.size.bytes(), self), &dest)?;
             }
 
+            NullaryOp(mir::NullOp::AlignOf, ty) => {
+                let ty = self.subst_from_current_frame_and_normalize_erasing_regions(ty);
+                let layout = self.layout_of(ty)?;
+                if layout.is_unsized() {
+                    // FIXME: This should be a span_bug (#80742)
+                    self.tcx.sess.delay_span_bug(
+                        self.frame().current_span(),
+                        &format!("SizeOf nullary MIR operator called for unsized type {}", ty),
+                    );
+                    throw_inval!(SizeOfUnsizedType(ty));
+                }
+                self.write_scalar(
+                    Scalar::from_machine_usize(layout.align.abi.bytes(), self),
+                    &dest,
+                )?;
+            }
+
             InitBox(ref operand, _) => {
                 let src = self.eval_operand(operand, None)?;
                 let v = self.read_immediate(&src)?;
diff --git a/compiler/rustc_mir/src/transform/check_consts/check.rs b/compiler/rustc_mir/src/transform/check_consts/check.rs
@@ -648,7 +648,7 @@ impl Visitor<'tcx> for Checker<'mir, 'tcx> {
                 }
             }
 
-            Rvalue::NullaryOp(NullOp::SizeOf, _) => {}
+            Rvalue::NullaryOp(NullOp::SizeOf | NullOp::AlignOf, _) => {}
             Rvalue::NullaryOp(NullOp::Box, _) => self.check_op(ops::HeapAllocation),
             Rvalue::InitBox(_, _) => {}
 
diff --git a/compiler/rustc_mir/src/transform/lower_intrinsics.rs b/compiler/rustc_mir/src/transform/lower_intrinsics.rs
@@ -105,6 +105,19 @@ impl<'tcx> MirPass<'tcx> for LowerIntrinsics {
                             terminator.kind = TerminatorKind::Goto { target };
                         }
                     }
+                    sym::min_align_of => {
+                        if let Some((destination, target)) = *destination {
+                            let tp_ty = substs.type_at(0);
+                            block.statements.push(Statement {
+                                source_info: terminator.source_info,
+                                kind: StatementKind::Assign(Box::new((
+                                    destination,
+                                    Rvalue::NullaryOp(NullOp::AlignOf, tp_ty),
+                                ))),
+                            });
+                            terminator.kind = TerminatorKind::Goto { target };
+                        }
+                    }
                     sym::discriminant_value => {
                         if let (Some((destination, target)), Some(arg)) =
                             (*destination, args[0].place())
diff --git a/compiler/rustc_mir/src/transform/promote_consts.rs b/compiler/rustc_mir/src/transform/promote_consts.rs
@@ -520,6 +520,7 @@ impl<'tcx> Validator<'_, 'tcx> {
             Rvalue::NullaryOp(op, _) => match op {
                 NullOp::Box => return Err(Unpromotable),
                 NullOp::SizeOf => {}
+                NullOp::AlignOf => {}
             },
 
             Rvalue::InitBox(_, _) => return Err(Unpromotable),
diff --git a/src/tools/clippy/clippy_utils/src/qualify_min_const_fn.rs b/src/tools/clippy/clippy_utils/src/qualify_min_const_fn.rs
@@ -194,7 +194,7 @@ fn check_rvalue(tcx: TyCtxt<'tcx>, body: &Body<'tcx>, def_id: DefId, rvalue: &Rv
                 ))
             }
         },
-        Rvalue::NullaryOp(NullOp::SizeOf, _) => Ok(()),
+        Rvalue::NullaryOp(NullOp::SizeOf | NullOp::AlignOf, _) => Ok(()),
         Rvalue::NullaryOp(NullOp::Box, _) => Err((span, "heap allocations are not allowed in const fn".into())),
         Rvalue::InitBox(_, _) => Ok(()),
         Rvalue::UnaryOp(_, operand) => {

Original file line number	Diff line number	Diff line change
`@@ -104,7 +104,6 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {`
`104`	`104`	`}`
`105`	`105`	`}`
`106`	`106`	`sym::pref_align_of`
`107`		`- \| sym::min_align_of`
`108`	`107`	`\| sym::needs_drop`
`109`	`108`	`\| sym::type_id`
`110`	`109`	`\| sym::type_name`
Original file line number	Diff line number	Diff line change
`@@ -2252,6 +2252,8 @@ impl BinOp {`
`2252`	`2252`	`pub enum NullOp {`
`2253`	`2253`	`/// Returns the size of a value of that type`
`2254`	`2254`	`SizeOf,`
	`2255`	`+ /// Returns the minimum alignment of a type`
	`2256`	`+ AlignOf,`
`2255`	`2257`	`/// Creates a new uninitialized box for a value of that type`
`2256`	`2258`	`Box,`
`2257`	`2259`	`}`
Original file line number	Diff line number	Diff line change
`@@ -648,7 +648,7 @@ impl Visitor<'tcx> for Checker<'mir, 'tcx> {`
`648`	`648`	`}`
`649`	`649`	`}`
`650`	`650`
`651`		`- Rvalue::NullaryOp(NullOp::SizeOf, _) => {}`
	`651`	`+ Rvalue::NullaryOp(NullOp::SizeOf \| NullOp::AlignOf, _) => {}`
`652`	`652`	`Rvalue::NullaryOp(NullOp::Box, _) => self.check_op(ops::HeapAllocation),`
`653`	`653`	`Rvalue::InitBox(_, _) => {}`
`654`	`654`
Original file line number	Diff line number	Diff line change
`@@ -194,7 +194,7 @@ fn check_rvalue(tcx: TyCtxt<'tcx>, body: &Body<'tcx>, def_id: DefId, rvalue: &Rv`
`194`	`194`	`))`
`195`	`195`	`}`
`196`	`196`	`},`
`197`		`- Rvalue::NullaryOp(NullOp::SizeOf, _) => Ok(()),`
	`197`	`+ Rvalue::NullaryOp(NullOp::SizeOf \| NullOp::AlignOf, _) => Ok(()),`
`198`	`198`	`Rvalue::NullaryOp(NullOp::Box, _) => Err((span, "heap allocations are not allowed in const fn".into())),`
`199`	`199`	`Rvalue::InitBox(_, _) => Ok(()),`
`200`	`200`	`Rvalue::UnaryOp(_, operand) => {`