Handle signature() for more libcalls (#6174)

* Handle signature() for more libcalls

This is necessary to be able to call them in the interpreter. All the
remaining libcalls which signature() doesn't handle are never used in
clif ir. Only in code compiled by a backend.

* Fix libcall declarations in cranelift-frontend

* Add function signatures

* Use correct pointer type instead of I64

cranelift/interpreter/src/state.rs

@@ -5,8 +5,8 @@ use crate::frame::Frame;
 use crate::interpreter::LibCallHandler;
 use cranelift_codegen::data_value::DataValue;
 use cranelift_codegen::ir::{
-    ExternalName, FuncRef, Function, GlobalValue, LibCall, MemFlags, Signature, StackSlot, Type,
-    Value,
+    types, ExternalName, FuncRef, Function, GlobalValue, LibCall, MemFlags, Signature, StackSlot,
+    Type, Value,
 };
 use cranelift_codegen::isa::CallConv;
 use smallvec::SmallVec;
@@ -96,7 +96,8 @@ impl<'a> InterpreterFunctionRef<'a> {
         match self {
             InterpreterFunctionRef::Function(f) => f.stencil.signature.clone(),
             // CallConv here is sort of irrelevant, since we don't use it for anything
-            InterpreterFunctionRef::LibCall(lc) => lc.signature(CallConv::SystemV),
+            // FIXME handle non-64bit systems
+            InterpreterFunctionRef::LibCall(lc) => lc.signature(CallConv::SystemV, types::I64),
         }
     }
 }