spv: load SPIRV-Headers' extinst.*.grammar.json to print `OpExtIn…

…st` instruction/operand names.

build.rs

@@ -0,0 +1,52 @@
+fn main() {
+    // HACK(eddyb) disable the default of re-running the build script on *any*
+    // change to *the entire source tree* (i.e. the default is roughly `./`).
+    println!("cargo:rerun-if-changed=build.rs");
+
+    let khr_spv_include_dir =
+        std::env::current_dir().unwrap().join("khronos-spec/SPIRV-Headers/include/spirv/unified1");
+    println!("cargo:rerun-if-changed={}", khr_spv_include_dir.display());
+
+    if !std::fs::metadata(&khr_spv_include_dir).map_or(false, |m| m.is_dir()) {
+        eprintln!(" error: {} is not a directory", khr_spv_include_dir.display());
+        eprintln!("  help: git submodules are required to build from a git checkout");
+        eprintln!("  help: run `git submodule update --init`");
+        eprintln!("  note: if the error persists, please open an issue");
+        std::process::exit(1);
+    }
+
+    let core_grammar = "spirv.core.grammar.json";
+    let mut extinsts_names_and_grammars: Vec<_> = std::fs::read_dir(&khr_spv_include_dir)
+        .unwrap()
+        .filter_map(|e| {
+            let file_name = e.unwrap().file_name();
+            Some((
+                file_name
+                    .to_str()?
+                    .strip_prefix("extinst.")?
+                    .strip_suffix(".grammar.json")?
+                    .to_string(),
+                file_name,
+            ))
+        })
+        .collect();
+    extinsts_names_and_grammars.sort();
+
+    let all_jsons = format!(
+        "pub(super) const SPIRV_CORE_GRAMMAR: &str = include_str!({:?});\n\
+         pub(super) const EXTINST_NAMES_AND_GRAMMARS: &[(&str, &str)] = &[\n{}];",
+        khr_spv_include_dir.join(core_grammar),
+        extinsts_names_and_grammars
+            .into_iter()
+            .map(|(name, grammar)| {
+                format!("({:?}, include_str!({:?})),\n", name, khr_spv_include_dir.join(grammar),)
+            })
+            .collect::<String>()
+    );
+    std::fs::write(
+        std::path::PathBuf::from(std::env::var_os("OUT_DIR").unwrap())
+            .join("khr_spv_grammar_jsons.rs"),
+        all_jsons,
+    )
+    .unwrap();
+}