Merge pull request #2778 from Ms2ger/parallel

Remove some mem::transmute calls and reduce some unsafe blocks in parallel.rs.

src/components/layout/parallel.rs

@@ -26,7 +26,7 @@ use servo_util::workqueue::{WorkQueue, WorkUnit, WorkerProxy};
 use std::mem;
 use std::ptr;
 use std::sync::atomics::{AtomicInt, Relaxed, SeqCst};
-use style::{Stylist, TNode};
+use style::TNode;
 
 #[allow(dead_code)]
 fn static_assertion(node: UnsafeLayoutNode) {
@@ -215,8 +215,7 @@ impl<'a> ParallelPostorderFlowTraversal for AssignHeightsAndStoreOverflowTravers
 
 fn recalc_style_for_node(unsafe_layout_node: UnsafeLayoutNode,
                          proxy: &mut WorkerProxy<*mut LayoutContext,UnsafeLayoutNode>) {
-    unsafe {
-        let layout_context: &mut LayoutContext = mem::transmute(*proxy.user_data());
+    let layout_context = unsafe { &mut **proxy.user_data() };
 
     // Get a real layout node.
     let node: LayoutNode = layout_node_from_unsafe_layout_node(&unsafe_layout_node);
@@ -237,8 +236,10 @@ fn recalc_style_for_node(unsafe_layout_node: UnsafeLayoutNode,
 
     // First, check to see whether we can share a style with someone.
     let style_sharing_candidate_cache = layout_context.style_sharing_candidate_cache();
-        let sharing_result = node.share_style_if_possible(style_sharing_candidate_cache,
-                                                          parent_opt.clone());
+    let sharing_result = unsafe {
+        node.share_style_if_possible(style_sharing_candidate_cache,
+                                     parent_opt.clone())
+    };
 
     // Otherwise, match and cascade selectors.
     match sharing_result {
@@ -247,14 +248,16 @@ fn recalc_style_for_node(unsafe_layout_node: UnsafeLayoutNode,
 
             if node.is_element() {
                 // Perform the CSS selector matching.
-                    let stylist: &Stylist = mem::transmute(layout_context.stylist);
+                let stylist = unsafe { &*layout_context.stylist };
                 node.match_node(stylist, &mut applicable_declarations, &mut shareable);
             }
 
             // Perform the CSS cascade.
+            unsafe {
                 node.cascade_node(parent_opt,
                                   &applicable_declarations,
                                   layout_context.applicable_declarations_cache());
+            }
 
             // Add ourselves to the LRU cache.
             if shareable {
@@ -299,14 +302,11 @@ fn recalc_style_for_node(unsafe_layout_node: UnsafeLayoutNode,
     // If we got here, we're a leaf. Start construction of flows for this node.
     construct_flows(unsafe_layout_node, proxy)
 }
-}
 
 fn construct_flows(mut unsafe_layout_node: UnsafeLayoutNode,
                    proxy: &mut WorkerProxy<*mut LayoutContext,UnsafeLayoutNode>) {
     loop {
-        let layout_context: &mut LayoutContext = unsafe {
-            mem::transmute(*proxy.user_data())
-        };
+        let layout_context = unsafe { &mut **proxy.user_data() };
 
         // Get a real layout node.
         let node: LayoutNode = layout_node_from_unsafe_layout_node(&unsafe_layout_node);
@@ -373,9 +373,7 @@ fn construct_flows(mut unsafe_layout_node: UnsafeLayoutNode,
 
 fn assign_widths(unsafe_flow: UnsafeFlow,
                  proxy: &mut WorkerProxy<*mut LayoutContext,UnsafeFlow>) {
-    let layout_context: &mut LayoutContext = unsafe {
-        mem::transmute(*proxy.user_data())
-    };
+    let layout_context = unsafe { &mut **proxy.user_data() };
     let mut assign_widths_traversal = AssignWidthsTraversal {
         layout_context: layout_context,
     };
@@ -384,9 +382,7 @@ fn assign_widths(unsafe_flow: UnsafeFlow,
 
 fn assign_heights_and_store_overflow(unsafe_flow: UnsafeFlow,
                                      proxy: &mut WorkerProxy<*mut LayoutContext,UnsafeFlow>) {
-    let layout_context: &mut LayoutContext = unsafe {
-        mem::transmute(*proxy.user_data())
-    };
+    let layout_context = unsafe { &mut **proxy.user_data() };
     let mut assign_heights_traversal = AssignHeightsAndStoreOverflowTraversal {
         layout_context: layout_context,
     };
@@ -449,9 +445,7 @@ fn compute_absolute_position(unsafe_flow: UnsafeFlow,
 
 fn build_display_list(mut unsafe_flow: UnsafeFlow,
                       proxy: &mut WorkerProxy<*mut LayoutContext,UnsafeFlow>) {
-    let layout_context: &mut LayoutContext = unsafe {
-        mem::transmute(*proxy.user_data())
-    };
+    let layout_context = unsafe { &mut **proxy.user_data() };
 
     loop {
         unsafe {
@@ -510,9 +504,7 @@ fn build_display_list(mut unsafe_flow: UnsafeFlow,
 pub fn recalc_style_for_subtree(root_node: &LayoutNode,
                                 layout_context: &mut LayoutContext,
                                 queue: &mut WorkQueue<*mut LayoutContext,UnsafeLayoutNode>) {
-    unsafe {
-        queue.data = mem::transmute(layout_context)
-    }
+    queue.data = layout_context as *mut _;
 
     // Enqueue the root node.
     queue.push(WorkUnit {
@@ -529,9 +521,7 @@ pub fn traverse_flow_tree_preorder(root: &mut FlowRef,
                                    time_profiler_chan: TimeProfilerChan,
                                    layout_context: &mut LayoutContext,
                                    queue: &mut WorkQueue<*mut LayoutContext,UnsafeFlow>) {
-    unsafe {
-        queue.data = mem::transmute(layout_context)
-    }
+    queue.data = layout_context as *mut _;
 
     profile(time::LayoutParallelWarmupCategory, time_profiler_chan, || {
         queue.push(WorkUnit {
@@ -549,9 +539,7 @@ pub fn build_display_list_for_subtree(root: &mut FlowRef,
                                       time_profiler_chan: TimeProfilerChan,
                                       layout_context: &mut LayoutContext,
                                       queue: &mut WorkQueue<*mut LayoutContext,UnsafeFlow>) {
-    unsafe {
-        queue.data = mem::transmute(layout_context)
-    }
+    queue.data = layout_context as *mut _;
 
     profile(time::LayoutParallelWarmupCategory, time_profiler_chan, || {
         queue.push(WorkUnit {