Add support for push constants generated by Clspv (#812)

When the -work-dim or -global-offset flags are passed to Clspv, it
will generate push constants. The sizes and offsets of the push
constant values are provided in the descriptor map. Amber needs to add
these to the pipeline layout and create a buffer for them.

7 files changed, 220 insertions, 0 deletions

diff --git a/src/clspv_helper.cc b/src/clspv_helper.cc
index 3dbb696..32edd07 100644
--- a/src/clspv_helper.cc
+++ b/src/clspv_helper.cc
@@ -94,6 +94,24 @@ Result Compile(Pipeline::ShaderInfo* shader_info,
 
       shader_info->AddDescriptorEntry(entry.kernel_arg_data.kernel_name,
                                       std::move(descriptor_entry));
+    } else if (entry.kind ==
+               clspv::version0::DescriptorMapEntry::PushConstant) {
+      Pipeline::ShaderInfo::PushConstant push_constant;
+      switch (entry.push_constant_data.pc) {
+        case clspv::PushConstant::Dimensions:
+          push_constant.type =
+              Pipeline::ShaderInfo::PushConstant::PushConstantType::kDimensions;
+          break;
+        case clspv::PushConstant::GlobalOffset:
+          push_constant.type = Pipeline::ShaderInfo::PushConstant::
+              PushConstantType::kGlobalOffset;
+          break;
+        default:
+          return Result("unhandled push constant generated by Clspv");
+      }
+      push_constant.offset = entry.push_constant_data.offset;
+      push_constant.size = entry.push_constant_data.size;
+      shader_info->AddPushConstant(std::move(push_constant));
     } else {
       assert(entry.kind == clspv::version0::DescriptorMapEntry::Sampler);
       // Create a new sampler info.
diff --git a/src/executor.cc b/src/executor.cc
index df204d6..0d428e9 100644
--- a/src/executor.cc
+++ b/src/executor.cc
@@ -71,6 +71,9 @@ Result Executor::Execute(Engine* engine,
       r = pipeline->GenerateOpenCLLiteralSamplers();
       if (!r.IsSuccess())
         return r;
+      r = pipeline->GenerateOpenCLPushConstants();
+      if (!r.IsSuccess())
+        return r;
     }
 
     for (auto& pipeline : script->GetPipelines()) {
diff --git a/src/pipeline.cc b/src/pipeline.cc
index 478e6e1..bebaf79 100644
--- a/src/pipeline.cc
+++ b/src/pipeline.cc
@@ -15,6 +15,7 @@
 #include "src/pipeline.h"
 
 #include <algorithm>
+#include <cstring>
 #include <limits>
 #include <set>
 
@@ -45,6 +46,7 @@ const uint32_t kOpenCLFilterModeLinearBit = 0x20;
 
 const char* Pipeline::kGeneratedColorBuffer = "framebuffer";
 const char* Pipeline::kGeneratedDepthBuffer = "depth_buffer";
+const char* Pipeline::kGeneratedPushConstantBuffer = "push_constant_buffer";
 
 Pipeline::ShaderInfo::ShaderInfo(Shader* shader, ShaderType type)
     : shader_(shader), shader_type_(type), entry_point_("main") {}
@@ -852,4 +854,62 @@ Result Pipeline::GenerateOpenCLLiteralSamplers() {
   return {};
 }
 
+Result Pipeline::GenerateOpenCLPushConstants() {
+  if (!IsCompute() || GetShaders().empty() ||
+      GetShaders()[0].GetShader()->GetFormat() != kShaderFormatOpenCLC) {
+    return {};
+  }
+
+  const auto& shader_info = GetShaders()[0];
+  if (shader_info.GetPushConstants().empty())
+    return {};
+
+  // Determine size and contents of the push constant buffer.
+  std::vector<uint32_t> bytes;
+  for (const auto& pc : shader_info.GetPushConstants()) {
+    assert(pc.size % sizeof(uint32_t) == 0);
+    assert(pc.offset % sizeof(uint32_t) == 0);
+    uint32_t elements = (pc.offset + pc.size) / sizeof(uint32_t);
+    if (elements > bytes.size()) {
+      bytes.resize(elements);
+    }
+
+    uint32_t base = pc.offset / sizeof(uint32_t);
+    switch (pc.type) {
+      case Pipeline::ShaderInfo::PushConstant::PushConstantType::kDimensions:
+        // All compute kernel launches are 3D.
+        bytes[base] = 3;
+        break;
+      case Pipeline::ShaderInfo::PushConstant::PushConstantType::kGlobalOffset:
+        // Global offsets are not currently supported.
+        bytes[base] = 0;
+        bytes[base + 1] = 0;
+        bytes[base + 2] = 0;
+        break;
+    }
+  }
+
+  TypeParser parser;
+  auto type = parser.Parse("R8_UINT");
+  auto fmt = MakeUnique<Format>(type.get());
+
+  // Create buffer containing push constant data.
+  std::unique_ptr<Buffer> buf = MakeUnique<Buffer>();
+  buf->SetName(kGeneratedPushConstantBuffer);
+  buf->SetFormat(fmt.get());
+  buf->SetSizeInBytes(static_cast<uint32_t>(bytes.size() * sizeof(uint32_t)));
+  std::memcpy(buf->ValuePtr()->data(), bytes.data(),
+              bytes.size() * sizeof(uint32_t));
+
+  Result r = SetPushConstantBuffer(buf.get());
+  if (!r.IsSuccess())
+    return r;
+
+  formats_.push_back(std::move(fmt));
+  types_.push_back(std::move(type));
+  opencl_push_constants_ = std::move(buf);
+
+  return {};
+}
+
 }  // namespace amber
diff --git a/src/pipeline.h b/src/pipeline.h
index a25b184..b565eca 100644
--- a/src/pipeline.h
+++ b/src/pipeline.h
@@ -112,6 +112,24 @@ class Pipeline {
       return descriptor_map_;
     }
 
+    /// Push constant information for an OpenCL-C shader.
+    struct PushConstant {
+      enum class PushConstantType {
+        kDimensions = 0,
+        kGlobalOffset,
+      };
+      PushConstantType type;
+      uint32_t offset = 0;
+      uint32_t size = 0;
+    };
+
+    void AddPushConstant(PushConstant&& pc) {
+      push_constants_.emplace_back(std::move(pc));
+    }
+    const std::vector<PushConstant>& GetPushConstants() const {
+      return push_constants_;
+    }
+
    private:
     Shader* shader_ = nullptr;
     ShaderType shader_type_;
@@ -121,6 +139,7 @@ class Pipeline {
     std::map<uint32_t, uint32_t> specialization_;
     std::unordered_map<std::string, std::vector<DescriptorMapEntry>>
         descriptor_map_;
+    std::vector<PushConstant> push_constants_;
     std::vector<std::string> compile_options_;
   };
 
@@ -157,6 +176,7 @@ class Pipeline {
 
   static const char* kGeneratedColorBuffer;
   static const char* kGeneratedDepthBuffer;
+  static const char* kGeneratedPushConstantBuffer;
 
   explicit Pipeline(PipelineType type);
   ~Pipeline();
@@ -318,6 +338,9 @@ class Pipeline {
   /// descriptor map. This should be called after all other samplers are bound.
   Result GenerateOpenCLLiteralSamplers();
 
+  /// Generate the push constant buffers necessary for OpenCL kernels.
+  Result GenerateOpenCLPushConstants();
+
  private:
   void UpdateFramebufferSizes();
 
@@ -346,6 +369,7 @@ class Pipeline {
   /// Maps (descriptor set, binding) to the buffer for that binding pair.
   std::map<std::pair<uint32_t, uint32_t>, Buffer*> opencl_pod_buffer_map_;
   std::vector<std::unique_ptr<Sampler>> opencl_literal_samplers_;
+  std::unique_ptr<Buffer> opencl_push_constants_;
 };
 
 }  // namespace amber
diff --git a/src/pipeline_test.cc b/src/pipeline_test.cc
index 7a2b2fe..de77369 100644
--- a/src/pipeline_test.cc
+++ b/src/pipeline_test.cc
@@ -821,4 +821,39 @@ TEST_F(PipelineTest, OpenCLGenerateLiteralSamplers) {
   }
 }
 
+TEST_F(PipelineTest, OpenCLGeneratePushConstants) {
+  Pipeline p(PipelineType::kCompute);
+  p.SetName("my_pipeline");
+
+  Shader cs(kShaderTypeCompute);
+  cs.SetFormat(kShaderFormatOpenCLC);
+  p.AddShader(&cs, kShaderTypeCompute);
+  p.SetShaderEntryPoint(&cs, "my_main");
+
+  Pipeline::ShaderInfo::PushConstant pc1;
+  pc1.type = Pipeline::ShaderInfo::PushConstant::PushConstantType::kDimensions;
+  pc1.offset = 0;
+  pc1.size = 4;
+  p.GetShaders()[0].AddPushConstant(std::move(pc1));
+
+  Pipeline::ShaderInfo::PushConstant pc2;
+  pc2.type =
+      Pipeline::ShaderInfo::PushConstant::PushConstantType::kGlobalOffset;
+  pc2.offset = 16;
+  pc2.size = 12;
+  p.GetShaders()[0].AddPushConstant(std::move(pc2));
+
+  auto r = p.GenerateOpenCLPushConstants();
+  ASSERT_TRUE(r.IsSuccess());
+
+  const auto& buf = p.GetPushConstantBuffer();
+  EXPECT_EQ(28U, buf.buffer->GetSizeInBytes());
+
+  const uint32_t* bytes = buf.buffer->GetValues<uint32_t>();
+  EXPECT_EQ(3U, bytes[0]);
+  EXPECT_EQ(0U, bytes[4]);
+  EXPECT_EQ(0U, bytes[5]);
+  EXPECT_EQ(0U, bytes[6]);
+}
+
 }  // namespace amber
diff --git a/tests/cases/opencl_generated_push_constants.amber b/tests/cases/opencl_generated_push_constants.amber
new file mode 100644
index 0000000..e479f5c
--- /dev/null
+++ b/tests/cases/opencl_generated_push_constants.amber
@@ -0,0 +1,79 @@
+#!amber
+# Copyright 2020 The Amber Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+SHADER compute work_dim_shader OPENCL-C
+kernel void foo(global int* out) {
+  *out = get_work_dim();
+}
+END
+
+SHADER compute global_offset_shader OPENCL-C
+kernel void foo(global int* out) {
+  out[0] = get_global_offset(0);
+  out[1] = get_global_offset(1);
+  out[2] = get_global_offset(2);
+}
+END
+
+SHADER compute all_constants_shader OPENCL-C
+kernel void foo(global int* out) {
+  out[0] = get_global_offset(0);
+  out[1] = get_global_offset(1);
+  out[2] = get_global_offset(2);
+  out[3] = get_work_dim();
+}
+END
+
+BUFFER work_dim_buf DATA_TYPE uint32 SIZE 1 FILL -1
+BUFFER global_offset_buf DATA_TYPE uint32 SIZE 3 FILL -1
+BUFFER all_constants_buf DATA_TYPE uint32 SIZE 4 FILL -1
+
+PIPELINE compute work_dim_pipeline
+  ATTACH work_dim_shader ENTRY_POINT foo
+  COMPILE_OPTIONS work_dim_shader
+     -work-dim
+  END
+  BIND BUFFER work_dim_buf AS storage DESCRIPTOR_SET 0 BINDING 0
+END
+
+PIPELINE compute global_offset_pipeline
+  ATTACH global_offset_shader ENTRY_POINT foo
+  COMPILE_OPTIONS global_offset_shader
+     -global-offset
+  END
+  BIND BUFFER global_offset_buf AS storage DESCRIPTOR_SET 0 BINDING 0
+END
+
+PIPELINE compute all_constants_pipeline
+  ATTACH all_constants_shader ENTRY_POINT foo
+  COMPILE_OPTIONS all_constants_shader
+     -work-dim -global-offset
+  END
+  BIND BUFFER all_constants_buf AS storage DESCRIPTOR_SET 0 BINDING 0
+END
+
+RUN work_dim_pipeline 1 1 1
+EXPECT work_dim_buf IDX 0 EQ 3
+
+RUN global_offset_pipeline 1 1 1
+EXPECT global_offset_buf IDX 0 EQ 0
+EXPECT global_offset_buf IDX 4 EQ 0
+EXPECT global_offset_buf IDX 8 EQ 0
+
+RUN all_constants_pipeline 1 1 1
+EXPECT all_constants_buf IDX 0 EQ 0
+EXPECT all_constants_buf IDX 4 EQ 0
+EXPECT all_constants_buf IDX 8 EQ 0
+EXPECT all_constants_buf IDX 12 EQ 3
diff --git a/tests/run_tests.py b/tests/run_tests.py
index 7d76050..b3903cd 100755
--- a/tests/run_tests.py
+++ b/tests/run_tests.py
@@ -95,6 +95,7 @@ SUPPRESSIONS_SWIFTSHADER = [
 OPENCL_CASES = [
   "opencl_bind_buffer.amber",
   "opencl_c_copy.amber",
+  "opencl_generated_push_constants.amber",
   "opencl_read_and_write_image3d_rgba32i.amber",
   "opencl_read_image.amber",
   "opencl_read_image_literal_sampler.amber",