Support statics in custom mir

Author: JakobDegen

compiler/rustc_mir_build/src/build/custom/parse/instruction.rs

@@ -1,3 +1,4 @@
+use rustc_middle::mir::interpret::{ConstValue, Scalar};
 use rustc_middle::{mir::*, thir::*, ty};
 
 use super::{parse_by_kind, PResult, ParseCtxt};
@@ -45,6 +46,8 @@ impl<'tcx, 'body> ParseCtxt<'tcx, 'body> {
     fn parse_operand(&self, expr_id: ExprId) -> PResult<Operand<'tcx>> {
         parse_by_kind!(self, expr_id, expr, "operand",
             @call("mir_move", args) => self.parse_place(args[0]).map(Operand::Move),
+            @call("mir_static", args) => self.parse_static(args[0]),
+            @call("mir_static_mut", args) => self.parse_static(args[0]),
             ExprKind::Literal { .. }
             | ExprKind::NamedConst { .. }
             | ExprKind::NonHirLiteral { .. }
@@ -79,4 +82,24 @@ impl<'tcx, 'body> ParseCtxt<'tcx, 'body> {
             ExprKind::VarRef { id } => Ok(self.block_map[id]),
         )
     }
+
+    fn parse_static(&self, expr_id: ExprId) -> PResult<Operand<'tcx>> {
+        let expr_id = parse_by_kind!(self, expr_id, _, "static",
+            ExprKind::Deref { arg } => *arg,
+        );
+
+        parse_by_kind!(self, expr_id, expr, "static",
+            ExprKind::StaticRef { alloc_id, ty, .. } => {
+                let const_val =
+                    ConstValue::Scalar(Scalar::from_pointer((*alloc_id).into(), &self.tcx));
+                let literal = ConstantKind::Val(const_val, *ty);
+
+                Ok(Operand::Constant(Box::new(Constant {
+                    span: expr.span,
+                    user_ty: None,
+                    literal
+                })))
+            },
+        )
+    }
 }

library/core/src/intrinsics/mir.rs

@@ -80,6 +80,8 @@ define!("mir_goto", fn Goto(destination: BasicBlock) -> BasicBlock);
 define!("mir_retag", fn Retag<T>(place: T));
 define!("mir_retag_raw", fn RetagRaw<T>(place: T));
 define!("mir_move", fn Move<T>(place: T) -> T);
+define!("mir_static", fn Static<T>(s: T) -> &'static T);
+define!("mir_static_mut", fn StaticMut<T>(s: T) -> *mut T);
 
 /// Convenience macro for generating custom MIR.
 ///

src/test/mir-opt/building/custom/consts.rs

@@ -18,6 +18,19 @@ fn consts<const C: u32>() {
     })
 }
 
+static S: i32 = 5;
+static mut T: i32 = 10;
+// EMIT_MIR consts.statics.built.after.mir
+#[custom_mir(dialect = "built")]
+fn statics() {
+    mir!({
+        let _a: &i32 = Static(S);
+        let _b: *mut i32 = StaticMut(T);
+        Return()
+    })
+}
+
 fn main() {
     consts::<5>();
+    statics();
 }

src/test/mir-opt/building/custom/consts.statics.built.after.mir

@@ -0,0 +1,27 @@
+// MIR for `statics` after built
+
+fn statics() -> () {
+    let mut _0: ();                      // return place in scope 0 at $DIR/consts.rs:25:14: 25:14
+    let mut _1: &i32;                    // in scope 0 at $SRC_DIR/core/src/intrinsics/mir.rs:LL:COL
+    let mut _2: *mut i32;                // in scope 0 at $SRC_DIR/core/src/intrinsics/mir.rs:LL:COL
+
+    bb0: {
+        _1 = const {alloc1: &i32};       // scope 0 at $DIR/consts.rs:+0:1: +0:13
+                                         // mir::Constant
+                                         // + span: $DIR/consts.rs:27:31: 27:32
+                                         // + literal: Const { ty: &i32, val: Value(Scalar(alloc1)) }
+        _2 = const {alloc2: *mut i32};   // scope 0 at $DIR/consts.rs:+0:1: +0:13
+                                         // mir::Constant
+                                         // + span: $DIR/consts.rs:28:38: 28:39
+                                         // + literal: Const { ty: *mut i32, val: Value(Scalar(alloc2)) }
+        return;                          // scope 0 at $DIR/consts.rs:+0:1: +0:13
+    }
+}
+
+alloc2 (static: T, size: 4, align: 4) {
+    0a 00 00 00                                     │ ....
+}
+
+alloc1 (static: S, size: 4, align: 4) {
+    05 00 00 00                                     │ ....
+}