rusticl/mesa: make PipeResource repr(transparent)

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30082>

src/gallium/frontends/rusticl/core/context.rs

@@ -81,7 +81,7 @@ impl Context {
 
         if !user_ptr.is_null() {
             res.iter()
-                .filter(|(_, r)| copy || !r.is_user)
+                .filter(|(_, r)| copy || !r.is_user())
                 .map(|(d, r)| {
                     d.helper_ctx()
                         .exec(|ctx| ctx.buffer_subdata(r, 0, user_ptr, size.try_into().unwrap()))
@@ -163,7 +163,7 @@ impl Context {
             let layer_stride = desc.slice_pitch();
 
             res.iter()
-                .filter(|(_, r)| copy || !r.is_user)
+                .filter(|(_, r)| copy || !r.is_user())
                 .map(|(d, r)| {
                     d.helper_ctx()
                         .exec(|ctx| ctx.texture_subdata(r, &bx, user_ptr, stride, layer_stride))

src/gallium/frontends/rusticl/core/memory.rs

@@ -712,7 +712,7 @@ impl MemBase {
 
     fn is_pure_user_memory(&self, d: &Device) -> CLResult<bool> {
         let r = self.get_res_of_dev(d)?;
-        Ok(r.is_user)
+        Ok(r.is_user())
     }
 
     fn map<T>(

src/gallium/frontends/rusticl/mesa/pipe/resource.rs

@@ -3,11 +3,13 @@ use mesa_rust_gen::*;
 use std::{mem, ptr};
 
 #[derive(PartialEq, Eq, Hash)]
+#[repr(transparent)]
 pub struct PipeResource {
     pipe: *mut pipe_resource,
-    pub is_user: bool,
 }
 
+const PIPE_RESOURCE_FLAG_RUSTICL_IS_USER: u32 = PIPE_RESOURCE_FLAG_FRONTEND_PRIV;
+
 // SAFETY: pipe_resource is considered a thread safe type
 unsafe impl Send for PipeResource {}
 unsafe impl Sync for PipeResource {}
@@ -68,10 +70,13 @@ impl PipeResource {
             return None;
         }
 
-        Some(Self {
-            pipe: res,
-            is_user: is_user,
-        })
+        if is_user {
+            unsafe {
+                res.as_mut().unwrap().flags |= PIPE_RESOURCE_FLAG_RUSTICL_IS_USER;
+            }
+        }
+
+        Some(Self { pipe: res })
     }
 
     pub(super) fn pipe(&self) -> *mut pipe_resource {
@@ -110,6 +115,10 @@ impl PipeResource {
         self.as_ref().usage() == pipe_resource_usage::PIPE_USAGE_STAGING
     }
 
+    pub fn is_user(&self) -> bool {
+        self.as_ref().flags & PIPE_RESOURCE_FLAG_RUSTICL_IS_USER != 0
+    }
+
     pub fn pipe_image_view(
         &self,
         format: pipe_format,