Move SkRasterPipeline further into SkOpts.

The portable code now becomes entirely focused on enum+ptr descriptions, leaving the concrete implementation of the pipeline to SkOpts::run_pipeline().

As implemented, the concrete implementation is basically the same, with a little more type safety.

Speed is essentially unchanged on my laptop, and that's having run_pipeline() rebuild its concrete state every call.  There's room for improvement there if we split this into a compile_pipeline() / run_pipeline() sort of thing, which is my next planned CL.

BUG=skia:

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=3920
CQ_INCLUDE_TRYBOTS=master.client.skia:Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-SKNX_NO_SIMD-Trybot

Change-Id: Ie4c554f51040426de7c5c144afa5d9d9d8938012
Reviewed-on: https://skia-review.googlesource.com/3920
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>

1 files changed, 8 insertions, 28 deletions

diff --git a/src/core/SkRasterPipeline.cpp b/src/core/SkRasterPipeline.cpp
index bc7feaccc7..707a33ae6f 100644
--- a/src/core/SkRasterPipeline.cpp
+++ b/src/core/SkRasterPipeline.cpp
@@ -8,40 +8,20 @@
 #include "SkOpts.h"
 #include "SkRasterPipeline.h"
 
-SkRasterPipeline::SkRasterPipeline() {
-    fBodyStart = SkOpts::body[just_return];
-    fTailStart = SkOpts::tail[just_return];
-}
-
-void SkRasterPipeline::append(void (*body)(), void (*tail)(), void* ctx) {
-    // Each stage holds its own context and the next function to call.
-    // So the pipeline itself has to hold onto the first function that starts the pipeline.
-    (fBody.empty() ? fBodyStart : fBody.back().fNext) = body;
-    (fTail.empty() ? fTailStart : fTail.back().fNext) = tail;
-
-    // Each last stage starts with its next function set to JustReturn as a safety net.
-    // It'll be overwritten by the next call to append().
-    fBody.push_back({ SkOpts::body[just_return], ctx });
-    fTail.push_back({ SkOpts::tail[just_return], ctx });
-}
+SkRasterPipeline::SkRasterPipeline() {}
 
 void SkRasterPipeline::append(StockStage stage, void* ctx) {
-    this->append(SkOpts::body[stage], SkOpts::tail[stage], ctx);
+    SkASSERT(fNum < (int)SK_ARRAY_COUNT(fStages));
+    fStages[fNum++] = { stage, ctx };
 }
 
 void SkRasterPipeline::extend(const SkRasterPipeline& src) {
-    SkASSERT(src.fBody.count() == src.fTail.count());
-
-    auto body = src.fBodyStart,
-         tail = src.fTailStart;
-    for (int i = 0; i < src.fBody.count(); i++) {
-        SkASSERT(src.fBody[i].fCtx == src.fTail[i].fCtx);
-        this->append(body, tail, src.fBody[i].fCtx);
-        body = src.fBody[i].fNext;
-        tail = src.fTail[i].fNext;
+    for (int i = 0; i < src.fNum; i++) {
+        const Stage& s = src.fStages[i];
+        this->append(s.stage, s.ctx);
     }
 }
 
-void SkRasterPipeline::run(size_t x, size_t n) {
-    SkOpts::run_pipeline(x,n, fBodyStart,fBody.begin(), fTailStart,fTail.begin());
+void SkRasterPipeline::run(size_t x, size_t n) const {
+    SkOpts::run_pipeline(x,n, fStages, fNum);
 }