From 489147c78b2091b87a80dac50a3e8f0f8eb42124 Mon Sep 17 00:00:00 2001
From: bsalomon <bsalomon@google.com>
Date: Mon, 14 Dec 2015 12:13:09 -0800
Subject: [PATCH] Add option to control maximum GrBatch lookback

Review URL: https://codereview.chromium.org/1498653002
---
 dm/DMSrcSink.cpp               | 14 +++++---------
 include/gpu/GrContextOptions.h |  4 ++++
 src/gpu/GrContext.cpp          |  1 +
 src/gpu/GrDrawTarget.cpp       |  9 ++++++---
 src/gpu/GrDrawTarget.h         |  4 +++-
 5 files changed, 19 insertions(+), 13 deletions(-)

diff --git a/dm/DMSrcSink.cpp b/dm/DMSrcSink.cpp
index 2503dc3..e27628a 100644
--- a/dm/DMSrcSink.cpp
+++ b/dm/DMSrcSink.cpp
@@ -810,19 +810,15 @@ void PreAbandonGpuContextErrorHandler(SkError, void*) {}
 DEFINE_bool(imm, false, "Run gpu configs in immediate mode.");
 DEFINE_bool(batchClip, false, "Clip each GrBatch to its device bounds for testing.");
 DEFINE_bool(batchBounds, false, "Draw a wireframe bounds of each GrBatch.");
+DEFINE_int32(batchLookback, -1, "Maximum GrBatch lookback for combining, negative means default.");
 
 Error GPUSink::draw(const Src& src, SkBitmap* dst, SkWStream*, SkString* log) const {
     GrContextOptions grOptions;
-    if (FLAGS_imm) {
-        grOptions.fImmediateMode = true;
-    }
-    if (FLAGS_batchClip) {
-        grOptions.fClipBatchToBounds = true;
-    }
+    grOptions.fImmediateMode = FLAGS_imm;
+    grOptions.fClipBatchToBounds = FLAGS_batchClip;
+    grOptions.fDrawBatchBounds = FLAGS_batchBounds;
+    grOptions.fMaxBatchLookback = FLAGS_batchLookback;
 
-    if (FLAGS_batchBounds) {
-        grOptions.fDrawBatchBounds = true;
-    }
     src.modifyGrContextOptions(&grOptions);
 
     GrContextFactory factory(grOptions);
diff --git a/include/gpu/GrContextOptions.h b/include/gpu/GrContextOptions.h
index 2874b52..8e6368a 100644
--- a/include/gpu/GrContextOptions.h
+++ b/include/gpu/GrContextOptions.h
@@ -22,6 +22,7 @@ struct GrContextOptions {
         , fImmediateMode(false)
         , fClipBatchToBounds(false)
         , fDrawBatchBounds(false)
+        , fMaxBatchLookback(-1)
         , fUseShaderSwizzling(false) {}
 
     // EXPERIMENTAL
@@ -63,6 +64,9 @@ struct GrContextOptions {
         of their dev bounds. */
     bool fDrawBatchBounds;
 
+    /** For debugging, override the default maximum look-back window for GrBatch combining. */
+    int fMaxBatchLookback;
+
     /** Force us to do all swizzling manually in the shader and don't rely on extensions to do
         swizzling. */
     bool fUseShaderSwizzling;
diff --git a/src/gpu/GrContext.cpp b/src/gpu/GrContext.cpp
index 1c30d54..2b20e17 100644
--- a/src/gpu/GrContext.cpp
+++ b/src/gpu/GrContext.cpp
@@ -89,6 +89,7 @@ void GrContext::initCommon(const GrContextOptions& options) {
     GrDrawTarget::Options dtOptions;
     dtOptions.fClipBatchToBounds = options.fClipBatchToBounds;
     dtOptions.fDrawBatchBounds = options.fDrawBatchBounds;
+    dtOptions.fMaxBatchLookback = options.fMaxBatchLookback;
     fDrawingManager.reset(new GrDrawingManager(this, dtOptions));
 
     // GrBatchFontCache will eventually replace GrFontCache
diff --git a/src/gpu/GrDrawTarget.cpp b/src/gpu/GrDrawTarget.cpp
index 59488c4..55f6624 100644
--- a/src/gpu/GrDrawTarget.cpp
+++ b/src/gpu/GrDrawTarget.cpp
@@ -32,6 +32,9 @@
 
 ////////////////////////////////////////////////////////////////////////////////
 
+// Experimentally we have found that most batching occurs within the first 10 comparisons.
+static const int kDefaultMaxBatchLookback = 10;
+
 GrDrawTarget::GrDrawTarget(GrRenderTarget* rt, GrGpu* gpu, GrResourceProvider* resourceProvider,
                            const Options& options)
     : fGpu(SkRef(gpu))
@@ -44,6 +47,8 @@ GrDrawTarget::GrDrawTarget(GrRenderTarget* rt, GrGpu* gpu, GrResourceProvider* r
     fClipMaskManager.reset(new GrClipMaskManager(this, options.fClipBatchToBounds));
 
     fDrawBatchBounds = options.fDrawBatchBounds;
+    fMaxBatchLookback = (options.fMaxBatchLookback < 0) ? kDefaultMaxBatchLookback :
+                                                          options.fMaxBatchLookback;
 
     rt->setLastDrawTarget(this);
 
@@ -469,8 +474,6 @@ void GrDrawTarget::recordBatch(GrBatch* batch) {
     // 1) check every draw
     // 2) intersect with something
     // 3) find a 'blocker'
-    // Experimentally we have found that most batching occurs within the first 10 comparisons.
-    static const int kMaxLookback = 10;
 
     GrBATCH_INFO("Re-Recording (%s, B%u)\n"
         "\tBounds LRTB (%f, %f, %f, %f)\n",
@@ -480,7 +483,7 @@ void GrDrawTarget::recordBatch(GrBatch* batch) {
         batch->bounds().fTop, batch->bounds().fBottom);
     GrBATCH_INFO(SkTabString(batch->dumpInfo(), 1).c_str());
     GrBATCH_INFO("\tOutcome:\n");    
-    int maxCandidates = SkTMin(kMaxLookback, fBatches.count());
+    int maxCandidates = SkTMin(fMaxBatchLookback, fBatches.count());
     if (maxCandidates) {
         int i = 0;
         while (true) {
diff --git a/src/gpu/GrDrawTarget.h b/src/gpu/GrDrawTarget.h
index c80ac34..42a6e79 100644
--- a/src/gpu/GrDrawTarget.h
+++ b/src/gpu/GrDrawTarget.h
@@ -44,9 +44,10 @@ class GrDrawTarget final : public SkRefCnt {
 public:
     /** Options for GrDrawTarget behavior. */
     struct Options {
-        Options () : fClipBatchToBounds(false), fDrawBatchBounds(false) {}
+        Options () : fClipBatchToBounds(false), fDrawBatchBounds(false), fMaxBatchLookback(-1) {}
         bool fClipBatchToBounds;
         bool fDrawBatchBounds;
+        int  fMaxBatchLookback;
     };
 
     GrDrawTarget(GrRenderTarget*, GrGpu*, GrResourceProvider*, const Options&);
@@ -297,6 +298,7 @@ private:
     GrRenderTarget*                             fRenderTarget;
 
     bool                                        fDrawBatchBounds;
+    int                                         fMaxBatchLookback;
 
     typedef SkRefCnt INHERITED;
 };
-- 
2.7.4