Remove pre-allocated clip space from GrRenderTargetOpList

It seems like this should be safe (perf-regression-wise) since the arena allocated clips are used infrequently.

In the following, each GM run has 621 srcs and a total of 81087 ops.
Each skp run has 87 srcs and a total of 14709 ops.
The following table shows how many times the arena allocator is called for each config/src.
Overall, I think is safe to only allocate the arena-allocated space on an as needed basis.

gl-gm:       0
gl-skp:      0

gl-msaa4:    0
gl-msaa4:    0

glinst-gm:   1225
glinst-skp:  579

glnvpr4-gm:  623
glnvpr4-skp: 77

Change-Id: I78e04b060b6ad3b78697519249bb4b9c3193fc85
Reviewed-on: https://skia-review.googlesource.com/14392
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>

2 files changed, 4 insertions, 5 deletions

diff --git a/src/gpu/GrRenderTargetOpList.cpp b/src/gpu/GrRenderTargetOpList.cpp
index 3abc21c131..5c81a92ab3 100644
--- a/src/gpu/GrRenderTargetOpList.cpp
+++ b/src/gpu/GrRenderTargetOpList.cpp
@@ -28,9 +28,7 @@ static const int kMaxOpLookahead = 10;
 GrRenderTargetOpList::GrRenderTargetOpList(sk_sp<GrRenderTargetProxy> proxy, GrGpu* gpu,
                                            GrAuditTrail* auditTrail)
         : INHERITED(std::move(proxy), auditTrail)
-        , fLastClipStackGenID(SK_InvalidUniqueID)
-        , fClipAllocator(fClipAllocatorStorage, sizeof(fClipAllocatorStorage),
-                         sizeof(fClipAllocatorStorage)) {
+        , fLastClipStackGenID(SK_InvalidUniqueID) {
     if (GrCaps::InstancedSupport::kNone != gpu->caps()->instancedSupport()) {
         fInstancedRendering.reset(gpu->createInstancedRendering());
     }
diff --git a/src/gpu/GrRenderTargetOpList.h b/src/gpu/GrRenderTargetOpList.h
index 4b3f0d0659..342f9278d5 100644
--- a/src/gpu/GrRenderTargetOpList.h
+++ b/src/gpu/GrRenderTargetOpList.h
@@ -150,8 +150,9 @@ private:
 
     SkSTArray<256, RecordedOp, true> fRecordedOps;
 
-    char fClipAllocatorStorage[4096];
-    SkArenaAlloc fClipAllocator;
+    // MDB TODO: 4096 for the first allocation of the clip space will be huge overkill.
+    // Gather statistics to determine the correct size.
+    SkArenaAlloc fClipAllocator{4096};
 
     typedef GrOpList INHERITED;
 };