impellerc GN rules

impeller/compiler/impellerc_main.cc

@@ -229,9 +229,9 @@ bool Main(const fml::CommandLine& command_line) {
   options.use_half_textures = switches.use_half_textures;
   options.require_framebuffer_fetch = switches.require_framebuffer_fetch;
 
-  if (!switches.iplr_bundle.empty()) {
+  if (!switches.shader_bundle.empty()) {
     // Invoke the compiler multiple times to build a shader bundle with the
-    // given iplr_bundle spec.
+    // given shader_bundle spec.
     return GenerateShaderBundle(switches, options);
   }
 

impeller/compiler/shader_bundle.cc

@@ -144,7 +144,7 @@ bool GenerateShaderBundle(Switches& switches, SourceOptions& options) {
   ///
 
   std::optional<ShaderBundleConfig> bundle_config =
-      ParseShaderBundleConfig(switches.iplr_bundle);
+      ParseShaderBundleConfig(switches.shader_bundle);
   if (!bundle_config) {
     return false;
   }

impeller/compiler/switches.cc

@@ -53,16 +53,17 @@ void Switches::PrintHelp(std::ostream& stream) {
   }
   stream << "}" << std::endl;
   stream << "--sl=<sl_output_file>" << std::endl;
-  stream << "--spirv=<spirv_output_file>" << std::endl;
+  stream << "--spirv=<spirv_output_file> (ignored for --shader-bundle)"
+         << std::endl;
   stream << "[optional] --source-language=glsl|hlsl (default: glsl)"
          << std::endl;
   stream << "[optional] --entry-point=<entry_point_name> (default: main; "
             "ignored for glsl)"
          << std::endl;
   stream << "[optional] --iplr (causes --sl file to be emitted in iplr format)"
          << std::endl;
-  stream << "[optional] --iplr-bundle=<bundle_spec> (causes --sl file to be "
-            "emitted in the iplr bundle format)"
+  stream << "[optional] --shader-bundle=<bundle_spec> (causes --sl file to be "
+            "emitted in Flutter GPU's shader bundle format)"
          << std::endl;
   stream << "[optional] --reflection-json=<reflection_json_file>" << std::endl;
   stream << "[optional] --reflection-header=<reflection_header_file>"
@@ -122,7 +123,8 @@ Switches::Switches(const fml::CommandLine& command_line)
       input_type(SourceTypeFromCommandLine(command_line)),
       sl_file_name(command_line.GetOptionValueWithDefault("sl", "")),
       iplr(command_line.HasOption("iplr")),
-      iplr_bundle(command_line.GetOptionValueWithDefault("iplr-bundle", "")),
+      shader_bundle(
+          command_line.GetOptionValueWithDefault("shader-bundle", "")),
       spirv_file_name(command_line.GetOptionValueWithDefault("spirv", "")),
       reflection_json_name(
           command_line.GetOptionValueWithDefault("reflection-json", "")),
@@ -193,6 +195,12 @@ Switches::Switches(const fml::CommandLine& command_line)
 }
 
 bool Switches::AreValid(std::ostream& explain) const {
+  // When producing a shader bundle, all flags related to single shader inputs
+  // and outputs such as `--input` and `--spirv-file-name` are ignored. Instead,
+  // input files are read from the shader bundle spec and a single flatbuffer
+  // containing all compiled shaders and reflection state is output to `--sl`.
+  const bool shader_bundle_mode = !shader_bundle.empty();
+
   bool valid = true;
   if (target_platform == TargetPlatform::kUnknown) {
     explain << "The target platform (only one) was not specified." << std::endl;
@@ -211,7 +219,7 @@ bool Switches::AreValid(std::ostream& explain) const {
     valid = false;
   }
 
-  if (source_file_name.empty()) {
+  if (source_file_name.empty() && !shader_bundle_mode) {
     explain << "Input file name was empty." << std::endl;
     valid = false;
   }
@@ -221,15 +229,15 @@ bool Switches::AreValid(std::ostream& explain) const {
     valid = false;
   }
 
-  if (spirv_file_name.empty()) {
+  if (spirv_file_name.empty() && !shader_bundle_mode) {
     explain << "Spirv file name was empty." << std::endl;
     valid = false;
   }
 
-  if (iplr && !iplr_bundle.empty()) {
-    explain
-        << "--iplr and --iplr-bundle flag cannot be specified at the same time"
-        << std::endl;
+  if (iplr && shader_bundle_mode) {
+    explain << "--iplr and --shader-bundle flag cannot be specified at the "
+               "same time"
+            << std::endl;
     valid = false;
   }
 

impeller/compiler/switches.h

@@ -22,9 +22,12 @@ struct Switches {
   std::vector<IncludeDir> include_directories = {};
   std::string source_file_name = "";
   SourceType input_type = SourceType::kUnknown;
+  /// The raw shader file output by the compiler. For --iplr and
+  /// --shader-bundle modes, this is used as the filename for the output
+  /// flatbuffer output.
   std::string sl_file_name = "";
   bool iplr = false;
-  std::string iplr_bundle = "";
+  std::string shader_bundle = "";
   std::string spirv_file_name = "";
   std::string reflection_json_name = "";
   std::string reflection_header_name = "";

impeller/compiler/types.cc

@@ -56,14 +56,6 @@ SourceType SourceTypeFromString(std::string name) {
     return SourceType::kFragmentShader;
   }
 
-  if (name == "tessellationcontrol") {
-    return SourceType::kTessellationControlShader;
-  }
-
-  if (name == "tessellationevaluation") {
-    return SourceType::kTessellationEvaluationShader;
-  }
-
   if (name == "compute") {
     return SourceType::kComputeShader;
   }

impeller/fixtures/BUILD.gn

@@ -121,9 +121,9 @@ impellerc("flutter_gpu_shaders") {
     "flutter_gpu_texture.frag",
     "flutter_gpu_texture.vert",
   ]
-  sl_file_extension = "shaderbundle"
   shader_target_flag = "--runtime-stage-metal"
-  iplr_bundle = "{\"UnlitFragment\": {\"type\": \"fragment\", \"file\": \"../../flutter/impeller/fixtures/flutter_gpu_unlit.frag\"}, \"UnlitVertex\": {\"type\": \"vertex\", \"file\": \"../../flutter/impeller/fixtures/flutter_gpu_unlit.vert\"}, \"TextureFragment\": {\"type\": \"fragment\", \"file\": \"../../flutter/impeller/fixtures/flutter_gpu_texture.frag\"}, \"TextureVertex\": {\"type\": \"vertex\", \"file\": \"../../flutter/impeller/fixtures/flutter_gpu_texture.vert\"}}"
+  shader_bundle = "{\"UnlitFragment\": {\"type\": \"fragment\", \"file\": \"../../flutter/impeller/fixtures/flutter_gpu_unlit.frag\"}, \"UnlitVertex\": {\"type\": \"vertex\", \"file\": \"../../flutter/impeller/fixtures/flutter_gpu_unlit.vert\"}, \"TextureFragment\": {\"type\": \"fragment\", \"file\": \"../../flutter/impeller/fixtures/flutter_gpu_texture.frag\"}, \"TextureVertex\": {\"type\": \"vertex\", \"file\": \"../../flutter/impeller/fixtures/flutter_gpu_texture.vert\"}}"
+  shader_bundle_output = "playground.shaderbundle"
 }
 
 test_fixtures("flutter_gpu_fixtures") {

impeller/tools/impeller.gni

@@ -242,18 +242,35 @@ template("embed_blob") {
 # the impeller_use_prebuilt_impellerc argument. Forwards all variables to
 # compiled_action_foreach or action_foreach as appropriate.
 template("_impellerc") {
-  if (impeller_use_prebuilt_impellerc == "") {
-    compiled_action_foreach(target_name) {
-      forward_variables_from(invoker, "*")
-      tool = "//flutter/impeller/compiler:impellerc"
+  if (invoker.single_invocation) {
+    if (impeller_use_prebuilt_impellerc == "") {
+      compiled_action(target_name) {
+        forward_variables_from(invoker, "*")
+        tool = "//flutter/impeller/compiler:impellerc"
+      }
+    } else {
+      action(target_name) {
+        forward_variables_from(invoker, "*", [ "args" ])
+        script = "//build/gn_run_binary.py"
+        impellerc_path =
+            rebase_path(impeller_use_prebuilt_impellerc, root_build_dir)
+        args = [ impellerc_path ] + invoker.args
+      }
     }
   } else {
-    action_foreach(target_name) {
-      forward_variables_from(invoker, "*", [ "args" ])
-      script = "//build/gn_run_binary.py"
-      impellerc_path =
-          rebase_path(impeller_use_prebuilt_impellerc, root_build_dir)
-      args = [ impellerc_path ] + invoker.args
+    if (impeller_use_prebuilt_impellerc == "") {
+      compiled_action_foreach(target_name) {
+        forward_variables_from(invoker, "*")
+        tool = "//flutter/impeller/compiler:impellerc"
+      }
+    } else {
+      action_foreach(target_name) {
+        forward_variables_from(invoker, "*", [ "args" ])
+        script = "//build/gn_run_binary.py"
+        impellerc_path =
+            rebase_path(impeller_use_prebuilt_impellerc, root_build_dir)
+        args = [ impellerc_path ] + invoker.args
+      }
     }
   }
 }
@@ -262,8 +279,13 @@ template("impellerc") {
   assert(defined(invoker.shaders), "Impeller shaders must be specified.")
   assert(defined(invoker.shader_target_flag),
          "The flag to impellerc for target selection must be specified.")
-  assert(defined(invoker.sl_file_extension),
+  assert(defined(invoker.sl_file_extension) || defined(invoker.shader_bundle),
          "The extension of the SL file must be specified (metal, glsl, etc..).")
+  if (defined(invoker.shader_bundle)) {
+    assert(
+        defined(invoker.shader_bundle_output),
+        "When shader_bundle is specified, shader_output_bundle must also be specified.")
+  }
 
   sksl = invoker.shader_target_flag == "--sksl"
   iplr = false
@@ -279,17 +301,26 @@ template("impellerc") {
   not_needed([
                "iplr",
                "sksl",
+               "shader_bundle",
+               "shader_bundle_output",
              ])
 
   # Optional: invoker.iplr Causes --sl output to be in iplr format.
-  # Optional: invoker.iplr_bundle specifies a Flutter GPU shader bundle configuration.
+  # Optional: invoker.shader_bundle specifies a Flutter GPU shader bundle configuration.
+  # Optional: invoker.shader_bundle_output specifies the output filename of the shader
+  #           bundle. This is required if invoker.shader_bundle is supplied.
   # Optional: invoker.defines specifies a list of valueless macro definitions.
   # Optional: invoker.intermediates_subdir specifies the subdirectory in which
   #           to put intermediates.
   # Optional: invoker.json Causes output format to be JSON instead of flatbuffer.
 
   _impellerc(target_name) {
-    sources = invoker.shaders
+    shader_bundle = defined(invoker.shader_bundle)
+
+    # When single_invocation is true, impellerc will be invoked exactly once. When it's
+    # false, impellerc be invoked for each of the source file entries (invoker.shaders).
+    single_invocation = shader_bundle
+
     if (defined(invoker.intermediates_subdir)) {
       subdir = invoker.intermediates_subdir
       generated_dir = "$target_gen_dir/$subdir"
@@ -299,22 +330,25 @@ template("impellerc") {
 
     shader_target_flag = invoker.shader_target_flag
 
-    spirv_intermediate = "$generated_dir/{{source_file_part}}.spirv"
-    spirv_intermediate_path = rebase_path(spirv_intermediate, root_build_dir)
-
     depfile_path = "$generated_dir/{{source_file_part}}.d"
     depfile_intermediate_path = rebase_path(depfile_path, root_build_dir)
     depfile = depfile_path
 
     shader_lib_dir = rebase_path("//flutter/impeller/compiler/shader_lib")
     args = [
-      "--input={{source}}",
-      "--include={{source_dir}}",
       "--include=$shader_lib_dir",
       "--depfile=$depfile_intermediate_path",
       "$shader_target_flag",
     ]
 
+    # When we're in single invocation mode, we can't use source enumeration.
+    if (!single_invocation) {
+      args += [
+        "--input={{source}}",
+        "--include={{source_dir}}",
+      ]
+    }
+
     if (defined(invoker.gles_language_version)) {
       gles_language_version = invoker.gles_language_version
       args += [ "--gles-language-version=$gles_language_version" ]
@@ -338,27 +372,60 @@ template("impellerc") {
       args += [ "--json" ]
     }
 
-    if (sksl) {
-      sl_intermediate =
+    if (iplr) {
+      # When building in IPLR mode, the compiler may be executed twice
+      args += [ "--iplr" ]
+    }
+
+    # The `sl_output` is the raw shader file output by the compiler. For --iplr
+    # and --shader-bundle, this is used as the filename for the flatbuffer to
+    # output.
+
+    if (shader_bundle) {
+      # When a shader bundle is specified, don't bother supplying flags for
+      # the reflection state as these are ignored. In this mode, the compiler
+      # is invoked multiple times and the reflection state for each shader is
+      # written to the output flatbuffer.
+      sl_output = "$generated_dir/${invoker.shader_bundle_output}"
+      sl_output_path = rebase_path(sl_output, root_build_dir)
+
+      args += [
+        "--sl=$sl_output_path",
+        "--shader-bundle=${invoker.shader_bundle}",
+      ]
+
+      outputs = [ sl_output ]
+    } else if (sksl) {
+      # When SkSL is selected as the `shader_target_flag`, don't generate
+      # C++ reflection state. Nothing needs to use it and it's likely invalid
+      # given the special cases when generating SkSL.
+      # Note that this configuration is orthogonal to the "--iplr" flag
+      sl_output =
           "$generated_dir/{{source_file_part}}.${invoker.sl_file_extension}"
-      sl_intermediate_path = rebase_path(sl_intermediate, root_build_dir)
+      sl_output_path = rebase_path(sl_output, root_build_dir)
+
+      spirv_intermediate = "$generated_dir/{{source_file_part}}.spirv"
+      spirv_intermediate_path = rebase_path(spirv_intermediate, root_build_dir)
       args += [
-        "--sl=$sl_intermediate_path",
+        "--sl=$sl_output_path",
         "--spirv=$spirv_intermediate_path",
       ]
-      if (iplr) {
-        args += [ "--iplr" ]
-      }
 
-      outputs = [ sl_intermediate ]
+      outputs = [ sl_output ]
     } else {
-      sl_intermediate =
+      # The default branch. Here we just generate one shader along with all of
+      # its C++ reflection state.
+
+      sl_output =
           "$generated_dir/{{source_file_part}}.${invoker.sl_file_extension}"
+      sl_output_path = rebase_path(sl_output, root_build_dir)
+
       reflection_json_intermediate = "$generated_dir/{{source_file_part}}.json"
       reflection_header_intermediate = "$generated_dir/{{source_file_part}}.h"
       reflection_cc_intermediate = "$generated_dir/{{source_file_part}}.cc"
 
-      sl_intermediate_path = rebase_path(sl_intermediate, root_build_dir)
+      spirv_intermediate = "$generated_dir/{{source_file_part}}.spirv"
+      spirv_intermediate_path = rebase_path(spirv_intermediate, root_build_dir)
       reflection_json_path =
           rebase_path(reflection_json_intermediate, root_build_dir)
       reflection_header_path =
@@ -367,21 +434,15 @@ template("impellerc") {
           rebase_path(reflection_cc_intermediate, root_build_dir)
 
       args += [
-        "--sl=$sl_intermediate_path",
+        "--sl=$sl_output_path",
         "--spirv=$spirv_intermediate_path",
         "--reflection-json=$reflection_json_path",
         "--reflection-header=$reflection_header_path",
         "--reflection-cc=$reflection_cc_path",
       ]
-      if (iplr) {
-        args += [ "--iplr" ]
-      }
-      if (defined(invoker.iplr_bundle)) {
-        args += [ "--iplr-bundle=${invoker.iplr_bundle}" ]
-      }
 
       outputs = [
-        sl_intermediate,
+        sl_output,
         reflection_header_intermediate,
         reflection_cc_intermediate,
       ]
@@ -392,6 +453,12 @@ template("impellerc") {
         args += [ "--define=$def" ]
       }
     }
+
+    if (single_invocation) {
+      inputs = invoker.shaders
+    } else {
+      sources = invoker.shaders
+    }
   }
 }