Add f16 and f128 configuration from compiler-builtins

In preparation of adding routines from these two types, duplicate the
`compiler-builtins` configuration here.

library/compiler-builtins/libm/crates/libm-test/Cargo.toml

@@ -5,7 +5,10 @@ edition = "2021"
 publish = false
 
 [features]
-default = []
+default = ["unstable-float"]
+
+# Propagated from libm because this affects which functions we test.
+unstable-float = ["libm/unstable-float"]
 
 # Generate tests which are random inputs and the outputs are calculated with
 # musl libc.
@@ -44,3 +47,9 @@ criterion = { version = "0.5.1", default-features = false, features = ["cargo_be
 [[bench]]
 name = "random"
 harness = false
+
+[lints.rust]
+# Values from the chared config.rs used by `libm` but not the test crate
+unexpected_cfgs = { level = "warn", check-cfg = [
+  'cfg(feature, values("arch", "force-soft-floats", "unstable-intrinsics"))',
+] }

library/compiler-builtins/libm/crates/libm-test/build.rs

@@ -1,66 +1,16 @@
 use std::fmt::Write;
-use std::path::PathBuf;
-use std::{env, fs};
+use std::fs;
+
+#[path = "../../configure.rs"]
+mod configure;
+use configure::Config;
 
 fn main() {
     let cfg = Config::from_env();
 
-    emit_optimization_cfg(&cfg);
-    emit_cfg_shorthands(&cfg);
     list_all_tests(&cfg);
-}
 
-#[allow(dead_code)]
-struct Config {
-    manifest_dir: PathBuf,
-    out_dir: PathBuf,
-    opt_level: u8,
-    target_arch: String,
-    target_env: String,
-    target_family: Option<String>,
-    target_os: String,
-    target_string: String,
-    target_vendor: String,
-    target_features: Vec<String>,
-}
-
-impl Config {
-    fn from_env() -> Self {
-        let target_features = env::var("CARGO_CFG_TARGET_FEATURE")
-            .map(|feats| feats.split(',').map(ToOwned::to_owned).collect())
-            .unwrap_or_default();
-
-        Self {
-            manifest_dir: PathBuf::from(env::var("CARGO_MANIFEST_DIR").unwrap()),
-            out_dir: PathBuf::from(env::var("OUT_DIR").unwrap()),
-            opt_level: env::var("OPT_LEVEL").unwrap().parse().unwrap(),
-            target_arch: env::var("CARGO_CFG_TARGET_ARCH").unwrap(),
-            target_env: env::var("CARGO_CFG_TARGET_ENV").unwrap(),
-            target_family: env::var("CARGO_CFG_TARGET_FAMILY").ok(),
-            target_os: env::var("CARGO_CFG_TARGET_OS").unwrap(),
-            target_string: env::var("TARGET").unwrap(),
-            target_vendor: env::var("CARGO_CFG_TARGET_VENDOR").unwrap(),
-            target_features,
-        }
-    }
-}
-
-/// Some tests are extremely slow. Emit a config option based on optimization level.
-fn emit_optimization_cfg(cfg: &Config) {
-    println!("cargo::rustc-check-cfg=cfg(optimizations_enabled)");
-
-    if cfg.opt_level >= 2 {
-        println!("cargo::rustc-cfg=optimizations_enabled");
-    }
-}
-
-/// Provide an alias for common longer config combinations.
-fn emit_cfg_shorthands(cfg: &Config) {
-    println!("cargo::rustc-check-cfg=cfg(x86_no_sse)");
-    if cfg.target_arch == "x86" && !cfg.target_features.iter().any(|f| f == "sse") {
-        // Shorthand to detect i586 targets
-        println!("cargo::rustc-cfg=x86_no_sse");
-    }
+    configure::emit_test_config(&cfg);
 }
 
 /// Create a list of all source files in an array. This can be used for making sure that