d72706c478
This is what most of the rest of the codebase does, so this patch just tidies up a few additional places.
65 lines
2.3 KiB
Rust
65 lines
2.3 KiB
Rust
//! Expanding instructions as runtime library calls.
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use ir;
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use ir::InstBuilder;
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use std::vec::Vec;
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/// Try to expand `inst` as a library call, returning true is successful.
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pub fn expand_as_libcall(inst: ir::Inst, func: &mut ir::Function) -> bool {
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// Does the opcode/ctrl_type combo even have a well-known runtime library name.
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let libcall =
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match ir::LibCall::for_inst(func.dfg[inst].opcode(), func.dfg.ctrl_typevar(inst)) {
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Some(lc) => lc,
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None => return false,
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};
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let funcref = find_funcref(libcall, func).unwrap_or_else(|| make_funcref(libcall, inst, func));
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// Now we convert `inst` to a call. First save the arguments.
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let mut args = Vec::new();
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args.extend_from_slice(func.dfg.inst_args(inst));
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// The replace builder will preserve the instruction result values.
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func.dfg.replace(inst).call(funcref, &args);
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// TODO: ask the ISA to legalize the signature.
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true
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}
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/// Get the existing function reference for `libcall` in `func` if it exists.
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fn find_funcref(libcall: ir::LibCall, func: &ir::Function) -> Option<ir::FuncRef> {
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// We're assuming that all libcall function decls are at the end.
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// If we get this wrong, worst case we'll have duplicate libcall decls which is harmless.
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for (fref, func_data) in func.dfg.ext_funcs.iter().rev() {
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match func_data.name {
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ir::ExternalName::LibCall(lc) => {
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if lc == libcall {
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return Some(fref);
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}
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}
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_ => break,
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}
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}
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None
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}
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/// Create a funcref for `libcall` with a signature matching `inst`.
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fn make_funcref(libcall: ir::LibCall, inst: ir::Inst, func: &mut ir::Function) -> ir::FuncRef {
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// Start with a system_v calling convention. We'll give the ISA a chance to change it.
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let mut sig = ir::Signature::new(ir::CallConv::SystemV);
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for &v in func.dfg.inst_args(inst) {
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sig.params.push(ir::AbiParam::new(func.dfg.value_type(v)));
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}
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for &v in func.dfg.inst_results(inst) {
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sig.returns.push(ir::AbiParam::new(func.dfg.value_type(v)));
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}
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let sigref = func.import_signature(sig);
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// TODO: Can libcalls be colocated in some circumstances?
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func.import_function(ir::ExtFuncData {
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name: ir::ExternalName::LibCall(libcall),
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signature: sigref,
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colocated: false,
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})
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}
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