1 files changed, 312 insertions, 0 deletions
diff --git a/gfx/wr/webrender/build.rs b/gfx/wr/webrender/build.rs
new file mode 100644
index 0000000000..df919f0949
--- /dev/null
+++ b/gfx/wr/webrender/build.rs
@@ -0,0 +1,312 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+extern crate webrender_build;
+
+use std::borrow::Cow;
+use std::env;
+use std::fs::{canonicalize, read_dir, File};
+use std::io::prelude::*;
+use std::path::{Path, PathBuf};
+use std::collections::hash_map::DefaultHasher;
+use std::hash::Hasher;
+use webrender_build::shader::*;
+use webrender_build::shader_features::{ShaderFeatureFlags, get_shader_features};
+
+/// Compute the shader path for insertion into the include_str!() macro.
+/// This makes for more compact generated code than inserting the literal
+/// shader source into the generated file.
+///
+/// If someone is building on a network share, I'm sorry.
+fn escape_include_path(path: &Path) -> String {
+    let full_path = canonicalize(path).unwrap();
+    let full_name = full_path.as_os_str().to_str().unwrap();
+    let full_name = full_name.replace("\\\\?\\", "");
+    let full_name = full_name.replace("\\", "/");
+
+    full_name
+}
+
+fn write_unoptimized_shaders(mut glsl_files: Vec<PathBuf>, shader_file: &mut File) -> Result<(), std::io::Error> {
+    writeln!(
+        shader_file,
+        "  pub static ref UNOPTIMIZED_SHADERS: HashMap<&'static str, SourceWithDigest> = {{"
+    )?;
+    writeln!(shader_file, "    let mut shaders = HashMap::new();")?;
+
+    // Sort the file list so that the shaders.rs file is filled
+    // deterministically.
+    glsl_files.sort_by(|a, b| a.file_name().cmp(&b.file_name()));
+
+    for glsl in glsl_files {
+        // Compute the shader name.
+        assert!(glsl.is_file());
+        let shader_name = glsl.file_name().unwrap().to_str().unwrap();
+        let shader_name = shader_name.replace(".glsl", "");
+
+        // Compute a digest of the #include-expanded shader source. We store
+        // this as a literal alongside the source string so that we don't need
+        // to hash large strings at runtime.
+        let mut hasher = DefaultHasher::new();
+        let base = glsl.parent().unwrap();
+        assert!(base.is_dir());
+        ShaderSourceParser::new().parse(
+            Cow::Owned(shader_source_from_file(&glsl)),
+            &|f| Cow::Owned(shader_source_from_file(&base.join(&format!("{}.glsl", f)))),
+            &mut |s| hasher.write(s.as_bytes()),
+        );
+        let digest: ProgramSourceDigest = hasher.into();
+
+        writeln!(
+            shader_file,
+            "    shaders.insert(\"{}\", SourceWithDigest {{ source: include_str!(\"{}\"), digest: \"{}\"}});",
+            shader_name,
+            escape_include_path(&glsl),
+            digest,
+        )?;
+    }
+    writeln!(shader_file, "    shaders")?;
+    writeln!(shader_file, "  }};")?;
+
+    Ok(())
+}
+
+#[derive(Clone, Debug)]
+struct ShaderOptimizationInput {
+    shader_name: &'static str,
+    config: String,
+    gl_version: ShaderVersion,
+}
+
+#[derive(Debug)]
+struct ShaderOptimizationOutput {
+    full_shader_name: String,
+    gl_version: ShaderVersion,
+    vert_file_path: PathBuf,
+    frag_file_path: PathBuf,
+    digest: ProgramSourceDigest,
+}
+
+#[derive(Debug)]
+struct ShaderOptimizationError {
+    shader: ShaderOptimizationInput,
+    message: String,
+}
+
+fn write_optimized_shaders(shader_dir: &Path, shader_file: &mut File, out_dir: &str) -> Result<(), std::io::Error> {
+    writeln!(
+        shader_file,
+        "  pub static ref OPTIMIZED_SHADERS: HashMap<(ShaderVersion, &'static str), OptimizedSourceWithDigest> = {{"
+    )?;
+    writeln!(shader_file, "    let mut shaders = HashMap::new();")?;
+
+    // The full set of optimized shaders can be quite large, so only optimize
+    // for the GL version we expect to be used on the target platform. If a different GL
+    // version is used we will simply fall back to the unoptimized shaders.
+    let shader_versions = match env::var("CARGO_CFG_TARGET_OS").as_ref().map(|s| &**s) {
+        Ok("android") | Ok("windows") => [ShaderVersion::Gles],
+        _ => [ShaderVersion::Gl],
+    };
+
+    let mut shaders = Vec::default();
+    for &gl_version in &shader_versions {
+        let mut flags = ShaderFeatureFlags::all();
+        if gl_version != ShaderVersion::Gl {
+            flags.remove(ShaderFeatureFlags::GL);
+        }
+        if gl_version != ShaderVersion::Gles {
+            flags.remove(ShaderFeatureFlags::GLES);
+            flags.remove(ShaderFeatureFlags::TEXTURE_EXTERNAL);
+        }
+        flags.remove(ShaderFeatureFlags::DITHERING);
+
+        for (shader_name, configs) in get_shader_features(flags) {
+            for config in configs {
+                shaders.push(ShaderOptimizationInput {
+                    shader_name,
+                    config,
+                    gl_version,
+                });
+            }
+        }
+    }
+
+    let outputs = build_parallel::compile_objects(&|shader: &ShaderOptimizationInput| {
+        println!("Optimizing shader {:?}", shader);
+        let target = match shader.gl_version {
+            ShaderVersion::Gl => glslopt::Target::OpenGl,
+            ShaderVersion::Gles => glslopt::Target::OpenGles30,
+        };
+        let glslopt_ctx = glslopt::Context::new(target);
+
+        let features = shader.config.split(",").filter(|f| !f.is_empty()).collect::<Vec<_>>();
+
+        let (vert_src, frag_src) = build_shader_strings(
+            shader.gl_version,
+            &features,
+            shader.shader_name,
+            &|f| Cow::Owned(shader_source_from_file(&shader_dir.join(&format!("{}.glsl", f)))),
+        );
+
+        let full_shader_name = if shader.config.is_empty() {
+            shader.shader_name.to_string()
+        } else {
+            format!("{}_{}", shader.shader_name, shader.config.replace(",", "_"))
+        };
+
+        let vert = glslopt_ctx.optimize(glslopt::ShaderType::Vertex, vert_src);
+        if !vert.get_status() {
+            return Err(ShaderOptimizationError {
+                shader: shader.clone(),
+                message: vert.get_log().to_string(),
+            });
+        }
+        let frag = glslopt_ctx.optimize(glslopt::ShaderType::Fragment, frag_src);
+        if !frag.get_status() {
+            return Err(ShaderOptimizationError {
+                shader: shader.clone(),
+                message: frag.get_log().to_string(),
+            });
+        }
+
+        let vert_source = vert.get_output().unwrap();
+        let frag_source = frag.get_output().unwrap();
+
+        // Compute a digest of the optimized shader sources. We store this
+        // as a literal alongside the source string so that we don't need
+        // to hash large strings at runtime.
+        let mut hasher = DefaultHasher::new();
+
+        let vert_file_path = Path::new(out_dir)
+            .join(format!("{}_{:?}.vert", full_shader_name, shader.gl_version));
+        write_optimized_shader_file(&vert_file_path, vert_source, &shader.shader_name, &features, &mut hasher);
+
+        let frag_file_path = vert_file_path.with_extension("frag");
+        write_optimized_shader_file(&frag_file_path, frag_source, &shader.shader_name, &features, &mut hasher);
+
+        let digest: ProgramSourceDigest = hasher.into();
+
+        println!("Finished optimizing shader {:?}", shader);
+
+        Ok(ShaderOptimizationOutput {
+            full_shader_name,
+            gl_version: shader.gl_version,
+            vert_file_path,
+            frag_file_path,
+            digest,
+        })
+    }, &shaders);
+
+    match outputs {
+        Ok(mut outputs) => {
+            // Sort the shader list so that the shaders.rs file is filled
+            // deterministically.
+            outputs.sort_by(|a, b| {
+                (a.gl_version, a.full_shader_name.clone()).cmp(&(b.gl_version, b.full_shader_name.clone()))
+            });
+
+            for shader in outputs {
+                writeln!(
+                    shader_file,
+                    "    shaders.insert(({}, \"{}\"), OptimizedSourceWithDigest {{",
+                    shader.gl_version.variant_name(),
+                    shader.full_shader_name,
+                )?;
+                writeln!(
+                    shader_file,
+                    "        vert_source: include_str!(\"{}\"),",
+                    escape_include_path(&shader.vert_file_path),
+                )?;
+                writeln!(
+                    shader_file,
+                    "        frag_source: include_str!(\"{}\"),",
+                    escape_include_path(&shader.frag_file_path),
+                )?;
+                writeln!(shader_file, "        digest: \"{}\",", shader.digest)?;
+                writeln!(shader_file, "    }});")?;
+            }
+        }
+        Err(err) => match err {
+            build_parallel::Error::BuildError(err) => {
+                panic!("Error optimizing shader {:?}: {}", err.shader, err.message)
+            }
+            _ => panic!("Error optimizing shaders."),
+        }
+    }
+
+    writeln!(shader_file, "    shaders")?;
+    writeln!(shader_file, "  }};")?;
+
+    Ok(())
+}
+
+fn write_optimized_shader_file(
+    path: &Path,
+    source: &str,
+    shader_name: &str,
+    features: &[&str],
+    hasher: &mut DefaultHasher,
+) {
+    let mut file = File::create(&path).unwrap();
+    for (line_number, line) in source.lines().enumerate() {
+        // We embed the shader name and features as a comment in the
+        // source to make debugging easier.
+        // The #version directive must be on the first line so we insert
+        // the extra information on the next line.
+        if line_number == 1 {
+            let prelude = format!(
+                "// {}\n// features: {:?}\n\n",
+                shader_name, features
+            );
+            file.write_all(prelude.as_bytes()).unwrap();
+            hasher.write(prelude.as_bytes());
+        }
+        file.write_all(line.as_bytes()).unwrap();
+        file.write_all("\n".as_bytes()).unwrap();
+        hasher.write(line.as_bytes());
+        hasher.write("\n".as_bytes());
+    }
+}
+
+fn main() -> Result<(), std::io::Error> {
+    let out_dir = env::var("OUT_DIR").unwrap_or("out".to_owned());
+
+    let shaders_file_path = Path::new(&out_dir).join("shaders.rs");
+    let mut glsl_files = vec![];
+
+    println!("cargo:rerun-if-changed=res");
+    let res_dir = Path::new("res");
+    for entry in read_dir(res_dir)? {
+        let entry = entry?;
+        let path = entry.path();
+
+        if entry.file_name().to_str().unwrap().ends_with(".glsl") {
+            println!("cargo:rerun-if-changed={}", path.display());
+            glsl_files.push(path.to_owned());
+        }
+    }
+
+    let mut shader_file = File::create(shaders_file_path)?;
+
+    writeln!(shader_file, "/// AUTO GENERATED BY build.rs\n")?;
+    writeln!(shader_file, "use std::collections::HashMap;\n")?;
+    writeln!(shader_file, "use webrender_build::shader::ShaderVersion;\n")?;
+    writeln!(shader_file, "pub struct SourceWithDigest {{")?;
+    writeln!(shader_file, "    pub source: &'static str,")?;
+    writeln!(shader_file, "    pub digest: &'static str,")?;
+    writeln!(shader_file, "}}\n")?;
+    writeln!(shader_file, "pub struct OptimizedSourceWithDigest {{")?;
+    writeln!(shader_file, "    pub vert_source: &'static str,")?;
+    writeln!(shader_file, "    pub frag_source: &'static str,")?;
+    writeln!(shader_file, "    pub digest: &'static str,")?;
+    writeln!(shader_file, "}}\n")?;
+    writeln!(shader_file, "lazy_static! {{")?;
+
+    write_unoptimized_shaders(glsl_files, &mut shader_file)?;
+    writeln!(shader_file, "")?;
+    write_optimized_shaders(&res_dir, &mut shader_file, &out_dir)?;
+    writeln!(shader_file, "}}")?;
+
+    Ok(())
+}