Noop away PushCull/PopCull pairs with nothing between them.

src/record/SkRecordOpts.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkRecordOpts.h"
 
 #include "SkRecordPattern.h"
 #include "SkRecords.h"
 #include "SkTDArray.h"
 
 using namespace SkRecords;
 
 void SkRecordOptimize(SkRecord* record) {
     // TODO(mtklein): fuse independent optimizations to reduce number of passes?
+    SkRecordNoopCulls(record);
     SkRecordNoopSaveRestores(record);
     SkRecordNoopSaveLayerDrawRestores(record);
+
     SkRecordAnnotateCullingPairs(record);
     SkRecordReduceDrawPosTextStrength(record);  // Helpful to run this before BoundDrawPosTextH.
     SkRecordBoundDrawPosTextH(record);
 }
 
 // Most of the optimizations in this file are pattern-based.  These are all defined as structs with:
 //   - a Pattern typedef
 //   - a bool onMatch(SkRceord*, Pattern*, unsigned begin, unsigned end) method,
 //     which returns true if it made changes and false if not.
 
 // Run a pattern-based optimization once across the SkRecord, returning true if it made any changes.
 // It looks for spans which match Pass::Pattern, and when found calls onMatch() with the pattern,
 // record, and [begin,end) span of the commands that matched.
 template <typename Pass>
 static bool apply(Pass* pass, SkRecord* record) {
     typename Pass::Pattern pattern;
     bool changed = false;
     unsigned begin, end = 0;
 
     while (pattern.search(record, &begin, &end)) {
         changed |= pass->onMatch(record, &pattern, begin, end);
     }
     return changed;
 }
 
+struct CullNooper {
+    typedef Pattern3<Is<PushCull>, Star<Is<NoOp> >, Is<PopCull> > Pattern;
+
+    bool onMatch(SkRecord* record, Pattern* pattern, unsigned begin, unsigned end) {
+        record->replace<NoOp>(begin);  // PushCull
+        record->replace<NoOp>(end-1);  // PopCull
+        return true;
+    }
+};
+
+void SkRecordNoopCulls(SkRecord* record) {
+    CullNooper pass;
+    while (apply(&pass, record));
+}
+
 // Turns the logical NoOp Save and Restore in Save-Draw*-Restore patterns into actual NoOps.
 struct SaveOnlyDrawsRestoreNooper {
     typedef Pattern3<Is<Save>,
                      Star<Or<Is<NoOp>, IsDraw> >,
                      Is<Restore> >
         Pattern;
 
     bool onMatch(SkRecord* record, Pattern* pattern, unsigned begin, unsigned end) {
         record->replace<NoOp>(begin);  // Save
         record->replace<NoOp>(end-1);  // Restore
@@ skipping 220 matching lines @@
     };
 
     SkTDArray<Pair> fPushStack;
     SkRecord* fRecord;
     unsigned fIndex;
 };
 void SkRecordAnnotateCullingPairs(SkRecord* record) {
     CullAnnotator pass;
     pass.apply(record);
 }