[meta] Move source generation responsibility into the meta crate itself;

cranelift/codegen/build.rs

@@ -20,7 +20,6 @@
 
 use cranelift_codegen_meta as meta;
 
-use crate::meta::isa::Isa;
 use std::env;
 use std::process;
 use std::time::Instant;
@@ -30,29 +29,31 @@ fn main() {
 
     let out_dir = env::var("OUT_DIR").expect("The OUT_DIR environment variable must be set");
     let target_triple = env::var("TARGET").expect("The TARGET environment variable must be set");
-    let cranelift_targets = env::var("CRANELIFT_TARGETS").ok();
-    let cranelift_targets = cranelift_targets.as_ref().map(|s| s.as_ref());
-    let python = identify_python();
 
     // Configure isa targets cfg.
-    match isa_targets(cranelift_targets, &target_triple) {
+    let cranelift_targets = env::var("CRANELIFT_TARGETS").ok();
-        Ok(isa_targets) => {
+    let cranelift_targets = cranelift_targets
-            for isa in &isa_targets {
+        .as_ref()
+        .map(|s| s.as_ref())
+        .filter(|s: &&str| s.len() > 0);
+
+    let isas = match cranelift_targets {
+        Some("native") => meta::isa_from_arch(&target_triple.split('-').next().unwrap()),
+        Some(targets) => meta::isas_from_targets(targets.split(',').collect::<Vec<_>>()),
+        None => meta::all_isas(),
+    }
+    .expect("Error when identifying CRANELIFT_TARGETS and TARGET");
+
+    for isa in &isas {
         println!("cargo:rustc-cfg=build_{}", isa.to_string());
     }
-        }
-        Err(err) => {
-            eprintln!("Error: {}", err);
-            process::exit(1);
-        }
-    }
 
     let cur_dir = env::current_dir().expect("Can't access current working directory");
     let crate_dir = cur_dir.as_path();
 
-    // Make sure we rebuild if this build script changes.
+    // Make sure we rebuild if this build script changes (will not happen with
-    // I guess that won't happen if you have non-UTF8 bytes in your path names.
+    // if the path to this file contains non-UTF8 bytes). The `build.py` script
-    // The `build.py` script prints out its own dependencies.
+    // prints out its own dependencies.
     println!(
         "cargo:rerun-if-changed={}",
         crate_dir.join("build.rs").to_str().unwrap()
@@ -65,6 +66,7 @@ fn main() {
     // Launch build script with Python. We'll just find python in the path.
     // Use -B to disable .pyc files, because they cause trouble for vendoring
     // scripts, and this is a build step that isn't run very often anyway.
+    let python = identify_python();
     let status = process::Command::new(python)
         .current_dir(crate_dir)
         .arg("-B")
@@ -83,12 +85,15 @@ fn main() {
     // emitted by the `meta` crate.
     // ------------------------------------------------------------------------
 
-    if let Err(err) = generate_meta(&out_dir) {
+    if let Err(err) = meta::generate(&isas, &out_dir) {
         eprintln!("Error: {}", err);
         process::exit(1);
     }
 
     if let Ok(_) = env::var("CRANELIFT_VERBOSE") {
+        for isa in &isas {
+            println!("cargo:warning=Includes support for {} ISA", isa.to_string());
+        }
         println!(
             "cargo:warning=Build step took {:?}.",
             Instant::now() - start_time
@@ -97,20 +102,6 @@ fn main() {
     }
 }
 
-fn generate_meta(out_dir: &str) -> Result<(), meta::error::Error> {
-    let shared_settings = meta::gen_settings::generate_common("new_settings.rs", &out_dir)?;
-    let isas = meta::isa::define_all(&shared_settings);
-
-    meta::gen_types::generate("types.rs", &out_dir)?;
-
-    for isa in &isas {
-        meta::gen_registers::generate(&isa, "registers", &out_dir)?;
-        meta::gen_settings::generate(&isa, "new_settings", &out_dir)?;
-    }
-
-    Ok(())
-}
-
 fn identify_python() -> &'static str {
     for python in &["python", "python3", "python2.7"] {
         if process::Command::new(python)
@@ -123,33 +114,3 @@ fn identify_python() -> &'static str {
     }
     panic!("The Cranelift build requires Python (version 2.7 or version 3)");
 }
-
-/// Returns isa targets to configure conditional compilation.
-fn isa_targets(cranelift_targets: Option<&str>, target_triple: &str) -> Result<Vec<Isa>, String> {
-    match cranelift_targets {
-        Some("native") => Isa::from_arch(target_triple.split('-').next().unwrap())
-            .map(|isa| vec![isa])
-            .ok_or_else(|| {
-                format!(
-                    "no supported isa found for target triple `{}`",
-                    target_triple
-                )
-            }),
-        Some(targets) => {
-            let unknown_isa_targets = targets
-                .split(',')
-                .filter(|target| Isa::new(target).is_none())
-                .collect::<Vec<_>>();
-            let isa_targets = targets.split(',').flat_map(Isa::new).collect::<Vec<_>>();
-            match (unknown_isa_targets.is_empty(), isa_targets.is_empty()) {
-                (true, true) => Ok(Isa::all().to_vec()),
-                (true, _) => Ok(isa_targets),
-                (_, _) => Err(format!(
-                    "unknown isa targets: `{}`",
-                    unknown_isa_targets.join(", ")
-                )),
-            }
-        }
-        None => Ok(Isa::all().to_vec()),
-    }
-}

cranelift/codegen/meta/src/isa/mod.rs

@@ -18,7 +18,7 @@ pub enum Isa {
 
 impl Isa {
     /// Creates isa target using name.
-    pub fn new(name: &str) -> Option<Self> {
+    pub fn from_name(name: &str) -> Option<Self> {
         Isa::all()
             .iter()
             .cloned()
@@ -27,28 +27,20 @@ impl Isa {
     }
 
     /// Creates isa target from arch.
-    pub fn from_arch(arch: &str) -> Option<Isa> {
+    pub fn from_arch(arch: &str) -> Option<Self> {
-        Isa::all()
+        match arch {
-            .iter()
+            "riscv" => Some(Isa::Riscv),
-            .cloned()
+            "aarch64" => Some(Isa::Arm64),
-            .filter(|isa| isa.is_arch_applicable(arch))
+            x if ["x86_64", "i386", "i586", "i686"].contains(&x) => Some(Isa::X86),
-            .next()
+            x if x.starts_with("arm") || arch.starts_with("thumb") => Some(Isa::Arm32),
+            _ => None,
+        }
     }
 
     /// Returns all supported isa targets.
     pub fn all() -> [Isa; 4] {
         [Isa::Riscv, Isa::X86, Isa::Arm32, Isa::Arm64]
     }
-
-    /// Checks if arch is applicable for the isa target.
-    fn is_arch_applicable(&self, arch: &str) -> bool {
-        match *self {
-            Isa::Riscv => arch == "riscv",
-            Isa::X86 => ["x86_64", "i386", "i586", "i686"].contains(&arch),
-            Isa::Arm32 => arch.starts_with("arm") || arch.starts_with("thumb"),
-            Isa::Arm64 => arch == "aarch64",
-        }
-    }
 }
 
 impl fmt::Display for Isa {
@@ -62,11 +54,13 @@ impl fmt::Display for Isa {
     }
 }
 
-pub fn define_all(shared_settings: &SettingGroup) -> Vec<TargetIsa> {
+pub fn define(isas: &Vec<Isa>, shared_settings: &SettingGroup) -> Vec<TargetIsa> {
-    vec![
+    isas.iter()
-        riscv::define(shared_settings),
+        .map(|isa| match isa {
-        arm32::define(shared_settings),
+            Isa::Riscv => riscv::define(shared_settings),
-        arm64::define(shared_settings),
+            Isa::X86 => x86::define(shared_settings),
-        x86::define(shared_settings),
+            Isa::Arm32 => arm32::define(shared_settings),
-    ]
+            Isa::Arm64 => arm64::define(shared_settings),
+        })
+        .collect()
 }

cranelift/codegen/meta/src/lib.rs

@@ -2,12 +2,70 @@
 mod cdsl;
 
 pub mod error;
-pub mod gen_registers;
-pub mod gen_settings;
-pub mod gen_types;
 pub mod isa;
 
+mod gen_registers;
+mod gen_settings;
+mod gen_types;
+
 mod base;
 mod constant_hash;
 mod srcgen;
 mod unique_table;
+
+pub fn isa_from_arch(arch: &str) -> Result<Vec<isa::Isa>, String> {
+    isa::Isa::from_arch(arch)
+        .ok_or_else(|| format!("no supported isa found for arch `{}`", arch))
+        .and_then(|isa| Ok(vec![isa]))
+}
+
+pub fn isas_from_targets(targets: Vec<&str>) -> Result<Vec<isa::Isa>, String> {
+    type R<'a> = Vec<(&'a str, Option<isa::Isa>)>;
+
+    let (known, unknown): (R, R) = targets
+        .into_iter()
+        .map(|target| (target, isa::Isa::from_name(target)))
+        .partition(|(_, opt_isa)| opt_isa.is_some());
+
+    if !unknown.is_empty() {
+        let unknown_targets = unknown
+            .into_iter()
+            .map(|(target, _)| target)
+            .collect::<Vec<_>>()
+            .join(", ");
+        return Err(format!("unknown isa targets: {}", unknown_targets));
+    }
+
+    let isas = if known.is_empty() {
+        isa::Isa::all().to_vec()
+    } else {
+        known
+            .into_iter()
+            .map(|(_, opt_isa)| opt_isa.unwrap())
+            .collect()
+    };
+
+    Ok(isas)
+}
+
+pub fn all_isas() -> Result<Vec<isa::Isa>, String> {
+    isas_from_targets(vec![])
+}
+
+/// Generates all the Rust source files used in Cranelift from the meta-language.
+pub fn generate(isas: &Vec<isa::Isa>, out_dir: &str) -> Result<(), error::Error> {
+    // Common definitions.
+    let shared_settings = gen_settings::generate_common("new_settings.rs", &out_dir)?;
+
+    gen_types::generate("types.rs", &out_dir)?;
+
+    // Per ISA definitions.
+    let isas = isa::define(isas, &shared_settings);
+
+    for isa in isas {
+        gen_registers::generate(&isa, "registers", &out_dir)?;
+        gen_settings::generate(&isa, "new_settings", &out_dir)?;
+    }
+
+    Ok(())
+}