Add some very basic support for the Intel32 ABI.

In 32-bit mode, all function arguments are passed on the stack, not in
registers.

This ABI support is not complete or properly tested, but at least it
doesn't try to pass arguments in r8.

lib/cretonne/src/isa/intel/abi.rs

@@ -106,9 +106,17 @@ impl ArgAssigner for Args {
 
 /// Legalize `sig`.
 pub fn legalize_signature(sig: &mut ir::Signature, flags: &shared_settings::Flags, _current: bool) {
-    let bits = if flags.is_64bit() { 64 } else { 32 };
+    let bits;
+    let mut args;
+
+    if flags.is_64bit() {
+        bits = 64;
+        args = Args::new(bits, &ARG_GPRS, 8);
+    } else {
+        bits = 32;
+        args = Args::new(bits, &[], 0);
+    }
 
-    let mut args = Args::new(bits, &ARG_GPRS, 8);
     legalize_args(&mut sig.argument_types, &mut args);
 
     let mut rets = Args::new(bits, &RET_GPRS, 2);