Show constant-foldable runs in SkRasterPipeline::dump().

Change-Id: I2f85249a09163dd21a8008f50340b8463718ada2
Reviewed-on: https://skia-review.googlesource.com/5350
Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Mike Klein <mtklein@chromium.org>

1 files changed, 58 insertions, 1 deletions

diff --git a/src/core/SkRasterPipeline.cpp b/src/core/SkRasterPipeline.cpp
index e52a2429b0..7c4c95f480 100644
--- a/src/core/SkRasterPipeline.cpp
+++ b/src/core/SkRasterPipeline.cpp
@@ -31,8 +31,54 @@ std::function<void(size_t, size_t, size_t)> SkRasterPipeline::compile() const {
     return SkOpts::compile_pipeline(fStages, fNum);
 }
 
+static bool invariant_in_x(const SkRasterPipeline::Stage& st) {
+    if (st.ctx == nullptr) {
+        // If a stage doesn't have a context pointer, it can't really do anything with x.
+        return true;
+    }
+
+    // This would be a lot more compact as a blacklist (the loads, the stores, the gathers),
+    // but it's safer to write as a whitelist.  If we get it wrong this way, not a big deal.
+    switch (st.stage) {
+        default: return false;
+
+        case SkRasterPipeline::trace:
+        case SkRasterPipeline::set_rgb:
+        case SkRasterPipeline::constant_color:
+        case SkRasterPipeline::scale_constant_float:
+        case SkRasterPipeline::lerp_constant_float:
+        case SkRasterPipeline::matrix_2x3:
+        case SkRasterPipeline::matrix_3x4:
+        case SkRasterPipeline::matrix_4x5:
+        case SkRasterPipeline::matrix_perspective:
+        case SkRasterPipeline::parametric_r:
+        case SkRasterPipeline::parametric_g:
+        case SkRasterPipeline::parametric_b:
+        case SkRasterPipeline::table_r:
+        case SkRasterPipeline::table_g:
+        case SkRasterPipeline::table_b:
+        case SkRasterPipeline::color_lookup_table:
+        case SkRasterPipeline::lab_to_xyz:
+        case SkRasterPipeline::clamp_x:
+        case SkRasterPipeline::mirror_x:
+        case SkRasterPipeline::repeat_x:
+        case SkRasterPipeline::clamp_y:
+        case SkRasterPipeline::mirror_y:
+        case SkRasterPipeline::repeat_y:
+        case SkRasterPipeline::top_left:
+        case SkRasterPipeline::top_right:
+        case SkRasterPipeline::bottom_left:
+        case SkRasterPipeline::bottom_right:
+        case SkRasterPipeline::accumulate:
+            SkASSERT(st.ctx != nullptr);
+            return true;
+    }
+    return false;
+}
+
 void SkRasterPipeline::dump() const {
     SkDebugf("SkRasterPipeline, %d stages\n", fNum);
+    bool in_constant_run = false;
     for (int i = 0; i < fNum; i++) {
         const char* name = "";
         switch (fStages[i].stage) {
@@ -40,7 +86,18 @@ void SkRasterPipeline::dump() const {
             SK_RASTER_PIPELINE_STAGES(M)
         #undef M
         }
-        SkDebugf("\t%s\n", name);
+
+        char mark = ' ';
+        if (fStages[i].stage == SkRasterPipeline::constant_color) {
+            mark = '*';
+            in_constant_run = true;
+        } else if (in_constant_run && invariant_in_x(fStages[i])) {
+            mark = '|';
+        } else {
+            mark = ' ';
+            in_constant_run = false;
+        }
+        SkDebugf("\t%c %s\n", mark, name);
     }
     SkDebugf("\n");
 }