moved crates in lib/ to src/, renamed crates, modified some files' text (#660)

moved crates in lib/ to src/, renamed crates, modified some files' text (#660)

cranelift/preopt/src/lib.rs

@@ -0,0 +1,55 @@
+//! Performs early-stage optimizations on Cranelift IR.
+
+#![deny(missing_docs, trivial_numeric_casts, unused_extern_crates)]
+#![warn(unused_import_braces)]
+#![cfg_attr(feature = "std", deny(unstable_features))]
+#![cfg_attr(feature = "clippy", plugin(clippy(conf_file = "../../clippy.toml")))]
+#![cfg_attr(feature = "cargo-clippy", allow(clippy::new_without_default))]
+#![cfg_attr(
+    feature = "cargo-clippy",
+    warn(
+        clippy::float_arithmetic,
+        clippy::mut_mut,
+        clippy::nonminimal_bool,
+        clippy::option_map_unwrap_or,
+        clippy::option_map_unwrap_or_else,
+        clippy::print_stdout,
+        clippy::unicode_not_nfc,
+        clippy::use_self
+    )
+)]
+#![no_std]
+#![cfg_attr(not(feature = "std"), feature(alloc))]
+
+#[cfg(not(feature = "std"))]
+#[macro_use]
+extern crate alloc as std;
+#[cfg(feature = "std")]
+#[macro_use]
+extern crate std;
+
+mod constant_folding;
+
+use cranelift_codegen::{isa::TargetIsa, settings::FlagsOrIsa, CodegenResult, Context};
+
+/// Optimize the function with available optimizations.
+///
+/// Since this can be resource intensive (and code-size inflating),
+/// it is separated from `Context::compile` to allow DCE to remove it
+/// if it's not used.
+pub fn optimize(ctx: &mut Context, isa: &TargetIsa) -> CodegenResult<()> {
+    ctx.verify_if(isa)?;
+    fold_constants(ctx, isa)?;
+
+    Ok(())
+}
+
+/// Fold constants
+pub fn fold_constants<'a, FOI>(ctx: &mut Context, fisa: FOI) -> CodegenResult<()>
+where
+    FOI: Into<FlagsOrIsa<'a>>,
+{
+    constant_folding::fold_constants(&mut ctx.func);
+    ctx.verify_if(fisa)?;
+    Ok(())
+}