[core] Split layer type specific code in mbgl::Programs

Progams code for a certain layer type is encapsulted within
a dedicated `<layer type>Programs` class, inherited from
the generic base `LayerTypePrograms` class.

`mbgl::Programs::get<layer type>Programs()` lazily initializes the
layer type-specific programs code using pointer to the base class,
which allows LTO to remove this code from binaries (if the corresponding
`get<layer type>Programs()` method can never be invoked).

cmake/core-files.txt

@@ -190,6 +190,7 @@ src/mbgl/programs/line_program.hpp
 src/mbgl/programs/program.hpp
 src/mbgl/programs/program_parameters.cpp
 src/mbgl/programs/program_parameters.hpp
+src/mbgl/programs/programs.cpp
 src/mbgl/programs/programs.hpp
 src/mbgl/programs/raster_program.cpp
 src/mbgl/programs/raster_program.hpp

src/mbgl/programs/background_program.hpp

@@ -80,4 +80,13 @@ class BackgroundPatternProgram : public Program<
 using BackgroundLayoutVertex = BackgroundProgram::LayoutVertex;
 using BackgroundAttributes = BackgroundProgram::Attributes;
 
+class BackgroundLayerPrograms final : public LayerTypePrograms  {
+public:
+    BackgroundLayerPrograms(gl::Context& context, const ProgramParameters& programParameters)
+        : background(context, programParameters),
+          backgroundPattern(context, programParameters) {}
+    BackgroundProgram background;
+    BackgroundPatternProgram backgroundPattern;
+};
+
 } // namespace mbgl

src/mbgl/programs/circle_program.hpp

@@ -48,4 +48,11 @@ class CircleProgram : public Program<
 using CircleLayoutVertex = CircleProgram::LayoutVertex;
 using CircleAttributes = CircleProgram::Attributes;
 
+class CircleLayerPrograms final : public LayerTypePrograms  {
+public:
+    CircleLayerPrograms(gl::Context& context, const ProgramParameters& programParameters)
+        : circle(context, programParameters) {}
+    ProgramMap<CircleProgram> circle;
+};
+
 } // namespace mbgl

src/mbgl/programs/fill_extrusion_program.hpp

@@ -2,6 +2,7 @@
 
 #include <mbgl/programs/program.hpp>
 #include <mbgl/programs/attributes.hpp>
+#include <mbgl/programs/extrusion_texture_program.hpp>
 #include <mbgl/programs/uniforms.hpp>
 #include <mbgl/shaders/fill_extrusion.hpp>
 #include <mbgl/shaders/fill_extrusion_pattern.hpp>
@@ -112,4 +113,16 @@ class FillExtrusionPatternProgram : public Program<
 using FillExtrusionLayoutVertex = FillExtrusionProgram::LayoutVertex;
 using FillExtrusionAttributes = FillExtrusionProgram::Attributes;
 
+
+class FillExtrusionLayerPrograms final : public LayerTypePrograms {
+public:
+    FillExtrusionLayerPrograms(gl::Context& context, const ProgramParameters& programParameters)
+        : fillExtrusion(context, programParameters),
+          fillExtrusionPattern(context, programParameters),
+          extrusionTexture(context, programParameters) {}
+    ProgramMap<FillExtrusionProgram> fillExtrusion;
+    ProgramMap<FillExtrusionPatternProgram> fillExtrusionPattern;
+    ExtrusionTextureProgram extrusionTexture;
+};
+
 } // namespace mbgl

src/mbgl/programs/fill_program.hpp

@@ -103,4 +103,17 @@ class FillOutlinePatternProgram : public Program<
 using FillLayoutVertex = FillProgram::LayoutVertex;
 using FillAttributes = FillProgram::Attributes;
 
+class FillLayerPrograms final : public LayerTypePrograms {
+public:
+    FillLayerPrograms(gl::Context& context, const ProgramParameters& programParameters)
+        : fill(context, programParameters),
+          fillPattern(context, programParameters),
+          fillOutline(context, programParameters),
+          fillOutlinePattern(context, programParameters) {}
+    ProgramMap<FillProgram> fill;
+    ProgramMap<FillPatternProgram> fillPattern;
+    ProgramMap<FillOutlineProgram> fillOutline;
+    ProgramMap<FillOutlinePatternProgram> fillOutlinePattern;
+};
+
 } // namespace mbgl

src/mbgl/programs/heatmap_program.hpp

@@ -2,6 +2,7 @@
 
 #include <mbgl/programs/program.hpp>
 #include <mbgl/programs/attributes.hpp>
+#include <mbgl/programs/heatmap_texture_program.hpp>
 #include <mbgl/programs/uniforms.hpp>
 #include <mbgl/shaders/heatmap.hpp>
 #include <mbgl/util/geometry.hpp>
@@ -46,4 +47,13 @@ class HeatmapProgram : public Program<
 using HeatmapLayoutVertex = HeatmapProgram::LayoutVertex;
 using HeatmapAttributes = HeatmapProgram::Attributes;
 
+class HeatmapLayerPrograms final : public LayerTypePrograms  {
+public:
+    HeatmapLayerPrograms(gl::Context& context, const ProgramParameters& programParameters) 
+        : heatmap(context, programParameters),
+          heatmapTexture(context, programParameters) {}
+    ProgramMap<HeatmapProgram> heatmap;
+    HeatmapTextureProgram heatmapTexture;
+};
+
 } // namespace mbgl

src/mbgl/programs/hillshade_program.hpp

@@ -2,6 +2,7 @@
 
 #include <mbgl/programs/program.hpp>
 #include <mbgl/programs/attributes.hpp>
+#include <mbgl/programs/hillshade_prepare_program.hpp>
 #include <mbgl/programs/uniforms.hpp>
 #include <mbgl/shaders/hillshade.hpp>
 #include <mbgl/util/geometry.hpp>
@@ -52,4 +53,13 @@ class HillshadeProgram : public Program<
 using HillshadeLayoutVertex = HillshadeProgram::LayoutVertex;
 using HillshadeAttributes = HillshadeProgram::Attributes;
 
+class HillshadeLayerPrograms final : public LayerTypePrograms  {
+public:
+    HillshadeLayerPrograms(gl::Context& context, const ProgramParameters& programParameters)
+        : hillshade(context, programParameters),
+          hillshadePrepare(context, programParameters) {}
+    HillshadeProgram hillshade;
+    HillshadePrepareProgram hillshadePrepare;
+};
+
 } // namespace mbgl

src/mbgl/programs/line_program.hpp

@@ -178,4 +178,17 @@ class LineGradientProgram : public Program<
 using LineLayoutVertex = LineProgram::LayoutVertex;
 using LineAttributes = LineProgram::Attributes;
 
+class LineLayerPrograms final : public LayerTypePrograms {
+public:
+    LineLayerPrograms(gl::Context& context, const ProgramParameters& programParameters)
+        : line(context, programParameters),
+          lineGradient(context, programParameters),
+          lineSDF(context, programParameters),
+          linePattern(context, programParameters) {}
+    ProgramMap<LineProgram> line;
+    ProgramMap<LineGradientProgram> lineGradient;
+    ProgramMap<LineSDFProgram> lineSDF;
+    ProgramMap<LinePatternProgram> linePattern;
+};
+
 } // namespace mbgl

src/mbgl/programs/program.hpp

@@ -133,4 +133,9 @@ class ProgramMap {
     std::unordered_map<Bitset, Program> programs;
 };
 
+class LayerTypePrograms {
+public:
+    virtual ~LayerTypePrograms() = default;
+};
+
 } // namespace mbgl

src/mbgl/programs/programs.cpp

@@ -0,0 +1,87 @@
+#include <mbgl/programs/programs.hpp>
+
+#include <mbgl/programs/background_program.hpp>
+#include <mbgl/programs/circle_program.hpp>
+#include <mbgl/programs/heatmap_program.hpp>
+#include <mbgl/programs/hillshade_program.hpp>
+#include <mbgl/programs/fill_extrusion_program.hpp>
+#include <mbgl/programs/fill_program.hpp>
+#include <mbgl/programs/line_program.hpp>
+#include <mbgl/programs/raster_program.hpp>
+#include <mbgl/programs/symbol_program.hpp>
+
+namespace mbgl {
+
+Programs::Programs(gl::Context& context_, const ProgramParameters& programParameters_)
+    : debug(context_, programParameters_),
+      clippingMask(context_, programParameters_),
+      context(context_),
+      programParameters(std::move(programParameters_)) {
+}
+
+Programs::~Programs() = default;
+
+BackgroundLayerPrograms& Programs::getBackgroundLayerPrograms() noexcept {
+    if (!backgroundPrograms) {
+        backgroundPrograms = std::make_unique<BackgroundLayerPrograms>(context, programParameters);
+    }
+    return static_cast<BackgroundLayerPrograms&>(*backgroundPrograms);   
+}
+
+RasterLayerPrograms& Programs::getRasterLayerPrograms() noexcept {
+    if (!rasterPrograms) {
+        rasterPrograms = std::make_unique<RasterLayerPrograms>(context, programParameters);
+    }
+    return static_cast<RasterLayerPrograms&>(*rasterPrograms);   
+}
+
+HeatmapLayerPrograms& Programs::getHeatmapLayerPrograms() noexcept {
+    if (!heatmapPrograms) {
+        heatmapPrograms = std::make_unique<HeatmapLayerPrograms>(context, programParameters);
+    }
+    return static_cast<HeatmapLayerPrograms&>(*heatmapPrograms);   
+}
+
+HillshadeLayerPrograms& Programs::getHillshadeLayerPrograms() noexcept {
+    if (!hillshadePrograms) {
+        hillshadePrograms = std::make_unique<HillshadeLayerPrograms>(context, programParameters);
+    }
+    return static_cast<HillshadeLayerPrograms&>(*hillshadePrograms);   
+}
+
+FillLayerPrograms& Programs::getFillLayerPrograms() noexcept {
+    if (!fillPrograms) {
+        fillPrograms = std::make_unique<FillLayerPrograms>(context, programParameters);
+    }
+    return static_cast<FillLayerPrograms&>(*fillPrograms);   
+}
+
+FillExtrusionLayerPrograms& Programs::getFillExtrusionLayerPrograms() noexcept {
+    if (!fillExtrusionPrograms) {
+        fillExtrusionPrograms = std::make_unique<FillExtrusionLayerPrograms>(context, programParameters);
+    }
+    return static_cast<FillExtrusionLayerPrograms&>(*fillExtrusionPrograms);   
+}
+
+CircleLayerPrograms& Programs::getCircleLayerPrograms() noexcept {
+    if (!circlePrograms) {
+        circlePrograms = std::make_unique<CircleLayerPrograms>(context, programParameters);
+    }
+    return static_cast<CircleLayerPrograms&>(*circlePrograms);   
+}
+
+LineLayerPrograms& Programs::getLineLayerPrograms() noexcept {
+    if (!linePrograms) {
+        linePrograms = std::make_unique<LineLayerPrograms>(context, programParameters);
+    }
+    return static_cast<LineLayerPrograms&>(*linePrograms);   
+}
+
+SymbolLayerPrograms& Programs::getSymbolLayerPrograms() noexcept {
+    if (!symbolPrograms) {
+        symbolPrograms = std::make_unique<SymbolLayerPrograms>(context, programParameters);
+    }
+    return static_cast<SymbolLayerPrograms&>(*symbolPrograms);   
+}
+
+} // namespace mbgl

src/mbgl/programs/programs.hpp

@@ -1,82 +1,54 @@
 #pragma once
 
-#include <mbgl/programs/background_program.hpp>
-#include <mbgl/programs/circle_program.hpp>
 #include <mbgl/programs/clipping_mask_program.hpp>
-#include <mbgl/programs/extrusion_texture_program.hpp>
-#include <mbgl/programs/fill_program.hpp>
-#include <mbgl/programs/fill_extrusion_program.hpp>
-#include <mbgl/programs/heatmap_program.hpp>
-#include <mbgl/programs/heatmap_texture_program.hpp>
-#include <mbgl/programs/hillshade_program.hpp>
-#include <mbgl/programs/hillshade_prepare_program.hpp>
-#include <mbgl/programs/line_program.hpp>
-#include <mbgl/programs/raster_program.hpp>
-#include <mbgl/programs/symbol_program.hpp>
 #include <mbgl/programs/debug_program.hpp>
-#include <mbgl/programs/collision_box_program.hpp>
 #include <mbgl/programs/program_parameters.hpp>
+#include <memory>
 
 namespace mbgl {
 
+class BackgroundLayerPrograms;
+
+class CircleLayerPrograms;
+class RasterLayerPrograms;
+class HeatmapLayerPrograms;
+class HillshadeLayerPrograms;
+class FillLayerPrograms;
+class FillExtrusionLayerPrograms;
+class LineLayerPrograms;
+class SymbolLayerPrograms;
+
 class Programs {
 public:
-    Programs(gl::Context& context, const ProgramParameters& programParameters)
-        : background(context, programParameters),
-          backgroundPattern(context, programParameters),
-          circle(context, programParameters),
-          extrusionTexture(context, programParameters),
-          fill(context, programParameters),
-          fillExtrusion(context, programParameters),
-          fillExtrusionPattern(context, programParameters),
-          fillPattern(context, programParameters),
-          fillOutline(context, programParameters),
-          fillOutlinePattern(context, programParameters),
-          heatmap(context, programParameters),
-          heatmapTexture(context, programParameters),
-          hillshade(context, programParameters),
-          hillshadePrepare(context, programParameters),
-          line(context, programParameters),
-          lineGradient(context, programParameters),
-          lineSDF(context, programParameters),
-          linePattern(context, programParameters),
-          raster(context, programParameters),
-          symbolIcon(context, programParameters),
-          symbolIconSDF(context, programParameters),
-          symbolGlyph(context, programParameters),
-          debug(context, programParameters),
-          collisionBox(context, programParameters),
-          collisionCircle(context, programParameters),
-          clippingMask(context, programParameters) {
-    }
+    Programs(gl::Context&, const ProgramParameters&);
+    ~Programs();
 
-    BackgroundProgram background;
-    BackgroundPatternProgram backgroundPattern;
-    ProgramMap<CircleProgram> circle;
-    ExtrusionTextureProgram extrusionTexture;
-    ProgramMap<FillProgram> fill;
-    ProgramMap<FillExtrusionProgram> fillExtrusion;
-    ProgramMap<FillExtrusionPatternProgram> fillExtrusionPattern;
-    ProgramMap<FillPatternProgram> fillPattern;
-    ProgramMap<FillOutlineProgram> fillOutline;
-    ProgramMap<FillOutlinePatternProgram> fillOutlinePattern;
-    ProgramMap<HeatmapProgram> heatmap;
-    HeatmapTextureProgram heatmapTexture;
-    HillshadeProgram hillshade;
-    HillshadePrepareProgram hillshadePrepare;
-    ProgramMap<LineProgram> line;
-    ProgramMap<LineGradientProgram> lineGradient;
-    ProgramMap<LineSDFProgram> lineSDF;
-    ProgramMap<LinePatternProgram> linePattern;
-    RasterProgram raster;
-    ProgramMap<SymbolIconProgram> symbolIcon;
-    ProgramMap<SymbolSDFIconProgram> symbolIconSDF;
-    ProgramMap<SymbolSDFTextProgram> symbolGlyph;
+    BackgroundLayerPrograms& getBackgroundLayerPrograms() noexcept;
+    RasterLayerPrograms& getRasterLayerPrograms() noexcept;
+    HeatmapLayerPrograms& getHeatmapLayerPrograms() noexcept;
+    CircleLayerPrograms& getCircleLayerPrograms() noexcept;
+    HillshadeLayerPrograms& getHillshadeLayerPrograms() noexcept;
+    FillLayerPrograms& getFillLayerPrograms() noexcept;
+    FillExtrusionLayerPrograms& getFillExtrusionLayerPrograms() noexcept;
+    LineLayerPrograms& getLineLayerPrograms() noexcept;
+    SymbolLayerPrograms& getSymbolLayerPrograms() noexcept;
 
     DebugProgram debug;
-    CollisionBoxProgram collisionBox;
-    CollisionCircleProgram collisionCircle;
     ClippingMaskProgram clippingMask;
+
+private:
+    std::unique_ptr<LayerTypePrograms> backgroundPrograms;
+    std::unique_ptr<LayerTypePrograms> circlePrograms;
+    std::unique_ptr<LayerTypePrograms> rasterPrograms;
+    std::unique_ptr<LayerTypePrograms> heatmapPrograms;
+    std::unique_ptr<LayerTypePrograms> hillshadePrograms;
+    std::unique_ptr<LayerTypePrograms> fillPrograms;
+    std::unique_ptr<LayerTypePrograms> fillExtrusionPrograms;
+    std::unique_ptr<LayerTypePrograms> linePrograms;
+    std::unique_ptr<LayerTypePrograms> symbolPrograms;
+
+    gl::Context& context;
+    ProgramParameters programParameters;
 };
 
 } // namespace mbgl

src/mbgl/programs/raster_program.hpp

@@ -65,4 +65,11 @@ class RasterProgram : public Program<
 using RasterLayoutVertex = RasterProgram::LayoutVertex;
 using RasterAttributes = RasterProgram::Attributes;
 
+class RasterLayerPrograms final : public LayerTypePrograms {
+public:
+    RasterLayerPrograms(gl::Context& context, const ProgramParameters& programParameters)
+        : raster(context, programParameters) {}
+    RasterProgram raster;
+};
+
 } // namespace mbgl

src/mbgl/programs/symbol_program.hpp

@@ -6,6 +6,7 @@
 #include <mbgl/util/interpolate.hpp>
 
 #include <mbgl/programs/attributes.hpp>
+#include <mbgl/programs/collision_box_program.hpp>
 #include <mbgl/programs/uniforms.hpp>
 #include <mbgl/programs/segment.hpp>
 #include <mbgl/shaders/symbol_icon.hpp>
@@ -448,4 +449,19 @@ using SymbolLayoutVertex = SymbolLayoutAttributes::Vertex;
 using SymbolIconAttributes = SymbolIconProgram::Attributes;
 using SymbolTextAttributes = SymbolSDFTextProgram::Attributes;
 
+class SymbolLayerPrograms final : public LayerTypePrograms {
+public:
+    SymbolLayerPrograms(gl::Context& context, const ProgramParameters& programParameters)
+        : symbolIcon(context, programParameters),
+          symbolIconSDF(context, programParameters),
+          symbolGlyph(context, programParameters),
+          collisionBox(context, programParameters),
+          collisionCircle(context, programParameters) {}
+    ProgramMap<SymbolIconProgram> symbolIcon;
+    ProgramMap<SymbolSDFIconProgram> symbolIconSDF;
+    ProgramMap<SymbolSDFTextProgram> symbolGlyph;
+    CollisionBoxProgram collisionBox;
+    CollisionCircleProgram collisionCircle;
+};
+
 } // namespace mbgl