Rollup merge of #110190 - cbeuw:mir-offset, r=oli-obk

Custom MIR: Support `BinOp::Offset`

Since offset doesn't have an infix operator, a new function `Offset` is added which is lowered to `Rvalue::BinaryOp(BinOp::Offset, ..)`

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

2 files changed, 21 insertions, 0 deletions

diff --git a/tests/mir-opt/building/custom/references.raw_pointer_offset.built.after.mir b/tests/mir-opt/building/custom/references.raw_pointer_offset.built.after.mir
new file mode 100644
index 00000000000..f614aef4029
--- /dev/null
+++ b/tests/mir-opt/building/custom/references.raw_pointer_offset.built.after.mir
@@ -0,0 +1,10 @@
+// MIR for `raw_pointer_offset` after built
+
+fn raw_pointer_offset(_1: *const i32) -> *const i32 {
+    let mut _0: *const i32;              // return place in scope 0 at $DIR/references.rs:+0:45: +0:55
+
+    bb0: {
+        _0 = Offset(_1, const 1_isize);  // scope 0 at $DIR/references.rs:+2:9: +2:33
+        return;                          // scope 0 at $DIR/references.rs:+3:9: +3:17
+    }
+}
diff --git a/tests/mir-opt/building/custom/references.rs b/tests/mir-opt/building/custom/references.rs
index a1c896de04c..f87f6664c7a 100644
--- a/tests/mir-opt/building/custom/references.rs
+++ b/tests/mir-opt/building/custom/references.rs
@@ -45,11 +45,22 @@ pub fn raw_pointer(x: *const i32) -> *const i32 {
     })
 }
 
+// EMIT_MIR references.raw_pointer_offset.built.after.mir
+#[custom_mir(dialect = "built")]
+pub fn raw_pointer_offset(x: *const i32) -> *const i32 {
+    mir!({
+        RET = Offset(x, 1_isize);
+        Return()
+    })
+}
+
 fn main() {
     let mut x = 5;
+    let arr = [1, 2];
     assert_eq!(*mut_ref(&mut x), 5);
     assert_eq!(*immut_ref(&x), 5);
     unsafe {
         assert_eq!(*raw_pointer(addr_of!(x)), 5);
+        assert_eq!(*raw_pointer_offset(addr_of!(arr[0])), 2);
     }
 }