stage2: elemPtr for slices

* Restructure elemPtr a bit
* New AIR instruction: slice_elem_ptr, which returns a pointer to an element of a slice
* Value: adapt elemPtr to work on slices

1 files changed, 14 insertions, 0 deletions

diff --git a/src/type.zig b/src/type.zig
index fceb3c4dfd..72347f5adc 100644
--- a/src/type.zig
+++ b/src/type.zig
@@ -2520,6 +2520,20 @@ pub const Type = extern union {
         };
     }
 
+    /// Returns the type of a pointer to an element.
+    /// Asserts that the type is a pointer, and that the element type is indexable.
+    /// For *[N]T, return *T
+    /// For [*]T, returns *T
+    /// For []T, returns *T
+    /// Handles const-ness and address spaces in particular.
+    pub fn elemPtrType(ptr_ty: Type, arena: *Allocator) !Type {
+        return try Type.ptr(arena, .{
+            .pointee_type = ptr_ty.elemType2(),
+            .mutable = ptr_ty.ptrIsMutable(),
+            .@"addrspace" = ptr_ty.ptrAddressSpace(),
+        });
+    }
+
     fn shallowElemType(child_ty: Type) Type {
         return switch (child_ty.zigTypeTag()) {
             .Array, .Vector => child_ty.childType(),