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/codegen/src/legalizer/libcall.rs

@@ -0,0 +1,31 @@
+//! Expanding instructions as runtime library calls.
+
+use crate::ir;
+use crate::ir::{get_libcall_funcref, InstBuilder};
+use crate::isa::TargetIsa;
+use crate::legalizer::boundary::legalize_libcall_signature;
+use std::vec::Vec;
+
+/// Try to expand `inst` as a library call, returning true is successful.
+pub fn expand_as_libcall(inst: ir::Inst, func: &mut ir::Function, isa: &TargetIsa) -> bool {
+    // Does the opcode/ctrl_type combo even have a well-known runtime library name.
+    let libcall = match ir::LibCall::for_inst(func.dfg[inst].opcode(), func.dfg.ctrl_typevar(inst))
+    {
+        Some(lc) => lc,
+        None => return false,
+    };
+
+    // Now we convert `inst` to a call. First save the arguments.
+    let mut args = Vec::new();
+    args.extend_from_slice(func.dfg.inst_args(inst));
+    // The replace builder will preserve the instruction result values.
+    let funcref = get_libcall_funcref(libcall, func, inst, isa);
+    func.dfg.replace(inst).call(funcref, &args);
+
+    // Ask the ISA to legalize the signature.
+    let fn_data = &func.dfg.ext_funcs[funcref];
+    let sig_data = &mut func.dfg.signatures[fn_data.signature];
+    legalize_libcall_signature(sig_data, isa);
+
+    true
+}