Rollup merge of #111587 - cbeuw:copy-for-deref, r=oli-obk

Custom MIR: Support `Rvalue::CopyForDeref`

r? `@oli-obk` or `@tmiasko` or `@JakobDegen`

3 files changed, 34 insertions, 11 deletions

diff --git a/tests/mir-opt/building/custom/projections.copy_for_deref.built.after.mir b/tests/mir-opt/building/custom/projections.copy_for_deref.built.after.mir
new file mode 100644
index 00000000000..5233d0489c6
--- /dev/null
+++ b/tests/mir-opt/building/custom/projections.copy_for_deref.built.after.mir
@@ -0,0 +1,12 @@
+// MIR for `copy_for_deref` after built
+
+fn copy_for_deref(_1: (&i32, i32)) -> i32 {
+    let mut _0: i32;                     // return place in scope 0 at $DIR/projections.rs:+0:38: +0:41
+    let mut _2: &i32;                    // in scope 0 at $SRC_DIR/core/src/intrinsics/mir.rs:LL:COL
+
+    bb0: {
+        _2 = deref_copy (_1.0: &i32);    // scope 0 at $DIR/projections.rs:+4:13: +4:37
+        _0 = (*_2);                      // scope 0 at $DIR/projections.rs:+5:13: +5:24
+        return;                          // scope 0 at $DIR/projections.rs:+6:13: +6:21
+    }
+}
diff --git a/tests/mir-opt/building/custom/projections.rs b/tests/mir-opt/building/custom/projections.rs
index 5e472e531c7..3c155deae4b 100644
--- a/tests/mir-opt/building/custom/projections.rs
+++ b/tests/mir-opt/building/custom/projections.rs
@@ -21,13 +21,10 @@ fn unions(u: U) -> i32 {
 #[custom_mir(dialect = "analysis", phase = "post-cleanup")]
 fn tuples(i: (u32, i32)) -> (u32, i32) {
     mir!(
-        // FIXME(JakobDegen): This is necessary because we can't give type hints for `RET`
-        let temp: (u32, i32);
+        type RET = (u32, i32);
         {
-            temp.0 = i.0;
-            temp.1 = i.1;
-
-            RET = temp;
+            RET.0 = i.0;
+            RET.1 = i.1;
             Return()
         }
     )
@@ -71,6 +68,19 @@ fn simple_index(a: [i32; 10], b: &[i32]) -> i32 {
     })
 }
 
+// EMIT_MIR projections.copy_for_deref.built.after.mir
+#[custom_mir(dialect = "runtime", phase = "initial")]
+fn copy_for_deref(x: (&i32, i32)) -> i32 {
+    mir!(
+        let temp: &i32;
+        {
+            temp = CopyForDeref(x.0);
+            RET = *temp;
+            Return()
+        }
+    )
+}
+
 fn main() {
     assert_eq!(unions(U { a: 5 }), 5);
     assert_eq!(tuples((5, 6)), (5, 6));
@@ -82,4 +92,7 @@ fn main() {
     assert_eq!(o, Some(10));
 
     assert_eq!(simple_index([0; 10], &[0; 10]), 0);
+
+    let one = 1;
+    assert_eq!(copy_for_deref((&one, one)), 1);
 }
diff --git a/tests/mir-opt/building/custom/projections.tuples.built.after.mir b/tests/mir-opt/building/custom/projections.tuples.built.after.mir
index 65487d3c9ed..dec575200c6 100644
--- a/tests/mir-opt/building/custom/projections.tuples.built.after.mir
+++ b/tests/mir-opt/building/custom/projections.tuples.built.after.mir
@@ -2,12 +2,10 @@
 
 fn tuples(_1: (u32, i32)) -> (u32, i32) {
     let mut _0: (u32, i32);              // return place in scope 0 at $DIR/projections.rs:+0:29: +0:39
-    let mut _2: (u32, i32);              // in scope 0 at $SRC_DIR/core/src/intrinsics/mir.rs:LL:COL
 
     bb0: {
-        (_2.0: u32) = (_1.0: u32);       // scope 0 at $DIR/projections.rs:+5:13: +5:25
-        (_2.1: i32) = (_1.1: i32);       // scope 0 at $DIR/projections.rs:+6:13: +6:25
-        _0 = _2;                         // scope 0 at $DIR/projections.rs:+8:13: +8:23
-        return;                          // scope 0 at $DIR/projections.rs:+9:13: +9:21
+        (_0.0: u32) = (_1.0: u32);       // scope 0 at $DIR/projections.rs:+4:13: +4:24
+        (_0.1: i32) = (_1.1: i32);       // scope 0 at $DIR/projections.rs:+5:13: +5:24
+        return;                          // scope 0 at $DIR/projections.rs:+6:13: +6:21
     }
 }