Skip flush in GrDrawingManager if the specifed proxy doesn't have any work

This is rather ham-fisted but I would like to have a short-term fix for the "always-flush" perf regressions.

Change-Id: Id359ad5a01a290e7e6c06f7ccc1c385ad47d2c06
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/206277
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>

include/private/GrOpList.h

@@ -113,6 +113,16 @@ protected:
 private:
     friend class GrDrawingManager; // for resetFlag, TopoSortTraits & gatherProxyIntervals
 
+    virtual bool onIsUsed(GrSurfaceProxy*) const = 0;
+
+    bool isUsed(GrSurfaceProxy* proxy) const {
+        if (proxy == fTarget.get()) {
+            return true;
+        }
+
+        return this->onIsUsed(proxy);
+    }
+
     void addDependency(GrOpList* dependedOn);
     void addDependent(GrOpList* dependent);
     SkDEBUGCODE(bool isDependedent(const GrOpList* dependent) const;)

src/gpu/GrDrawingManager.cpp

@@ -72,6 +72,16 @@ void GrDrawingManager::OpListDAG::removeOpLists(int startIndex, int stopIndex) {
     }
 }
 
+bool GrDrawingManager::OpListDAG::isUsed(GrSurfaceProxy* proxy) const {
+    for (int i = 0; i < fOpLists.count(); ++i) {
+        if (fOpLists[i] && fOpLists[i]->isUsed(proxy)) {
+            return true;
+        }
+    }
+
+    return false;
+}
+
 void GrDrawingManager::OpListDAG::add(sk_sp<GrOpList> opList) {
     fOpLists.emplace_back(std::move(opList));
 }
@@ -209,6 +219,10 @@ GrSemaphoresSubmitted GrDrawingManager::flush(GrSurfaceProxy* proxy,
 
     SkDEBUGCODE(this->validate());
 
+    if (SkSurface::kNone_FlushFlags == flags && !numSemaphores && proxy && !fDAG.isUsed(proxy)) {
+        return GrSemaphoresSubmitted::kNo;
+    }
+
     auto direct = fContext->priv().asDirectContext();
     if (!direct) {
         return GrSemaphoresSubmitted::kNo; // Can't flush while DDL recording

src/gpu/GrDrawingManager.h

@@ -118,6 +118,8 @@ private:
         bool empty() const { return fOpLists.empty(); }
         int numOpLists() const { return fOpLists.count(); }
 
+        bool isUsed(GrSurfaceProxy*) const;
+
         GrOpList* opList(int index) { return fOpLists[index].get(); }
         const GrOpList* opList(int index) const { return fOpLists[index].get(); }
 

src/gpu/GrRenderTargetOpList.cpp

@@ -610,6 +610,21 @@ void GrRenderTargetOpList::purgeOpsWithUninstantiatedProxies() {
     }
 }
 
+bool GrRenderTargetOpList::onIsUsed(GrSurfaceProxy* proxyToCheck) const {
+    bool used = false;
+
+    auto visit = [ proxyToCheck, &used ] (GrSurfaceProxy* p) {
+        if (p == proxyToCheck) {
+            used = true;
+        }
+    };
+    for (const OpChain& recordedOp : fOpChains) {
+        recordedOp.visitProxies(visit, GrOp::VisitorType::kOther);
+    }
+
+    return used;
+}
+
 void GrRenderTargetOpList::gatherProxyIntervals(GrResourceAllocator* alloc) const {
 
     for (int i = 0; i < fDeferredProxies.count(); ++i) {

src/gpu/GrRenderTargetOpList.h

@@ -126,6 +126,8 @@ private:
     // however, requires that the RTC be able to coordinate with the op list to achieve similar ends
     friend class GrRenderTargetContext;
 
+    bool onIsUsed(GrSurfaceProxy*) const override;
+
     // Must only be called if native stencil buffer clearing is enabled
     void setStencilLoadOp(GrLoadOp op);
     // Must only be called if native color buffer clearing is enabled.

src/gpu/GrTextureOpList.cpp

@@ -180,6 +180,24 @@ void GrTextureOpList::purgeOpsWithUninstantiatedProxies() {
     }
 }
 
+bool GrTextureOpList::onIsUsed(GrSurfaceProxy* proxyToCheck) const {
+    bool used = false;
+
+    auto visit = [ proxyToCheck, &used ] (GrSurfaceProxy* p) {
+        if (p == proxyToCheck) {
+            used = true;
+        }
+    };
+    for (int i = 0; i < fRecordedOps.count(); ++i) {
+        const GrOp* op = fRecordedOps[i].get();
+        if (op) {
+            op->visitProxies(visit, GrOp::VisitorType::kOther);
+        }
+    }
+
+    return used;
+}
+
 void GrTextureOpList::gatherProxyIntervals(GrResourceAllocator* alloc) const {
 
     // Add the interval for all the writes to this opList's target

src/gpu/GrTextureOpList.h

@@ -59,6 +59,8 @@ public:
     SkDEBUGCODE(void dump(bool printDependencies) const override;)
 
 private:
+    bool onIsUsed(GrSurfaceProxy*) const override;
+
     void deleteOp(int index);
     void deleteOps();