make variadic args explicit

Some abis, like the riscv one, treat
arguments differently depending on
whether they are variadic or not.
To prepare for the upcomming riscv
target, we change the variadic call
syntax and give meaning to the
location of the '...' marker.

  # new syntax
  %ret =w call $f(w %regular, ..., w %variadic)

By nature of their abis, the change
is backwards compatible for existing
targets.

1 files changed, 11 insertions, 6 deletions

diff --git a/arm64/abi.c b/arm64/abi.c
index 5fe9553..d38dcf5 100644
--- a/arm64/abi.c
+++ b/arm64/abi.c
@@ -255,6 +255,10 @@ argsclass(Ins *i0, Ins *i1, Class *carg, Ref *env)
 		case Oarge:
 			*env = i->arg[0];
 			break;
+		case Oargv:
+			break;
+		default:
+			die("unreachable");
 		}
 
 	return ((gp-gpreg) << 5) | ((fp-fpreg) << 9);
@@ -371,10 +375,11 @@ selcall(Fn *fn, Ins *i0, Ins *i1, Insl **ilp)
 		}
 	}
 
+	emit(Ocall, 0, R, i1->arg[0], CALL(cty));
+
 	envc = !req(R, env);
 	if (envc)
 		die("todo (arm abi): env calls");
-	emit(Ocall, 0, R, i1->arg[0], CALL(cty));
 
 	if (cty & (1 << 13))
 		/* struct return argument */
@@ -383,9 +388,9 @@ selcall(Fn *fn, Ins *i0, Ins *i1, Insl **ilp)
 	for (i=i0, c=ca; i<i1; i++, c++) {
 		if ((c->class & Cstk) != 0)
 			continue;
-		if (i->op != Oargc)
+		if (i->op == Oarg)
 			emit(Ocopy, *c->cls, TMP(*c->reg), i->arg[0], R);
-		else
+		if (i->op == Oargc)
 			ldregs(c->reg, c->cls, c->nreg, i->arg[1], fn);
 	}
 
@@ -393,11 +398,12 @@ selcall(Fn *fn, Ins *i0, Ins *i1, Insl **ilp)
 	for (i=i0, c=ca; i<i1; i++, c++) {
 		if ((c->class & Cstk) == 0)
 			continue;
-		if (i->op != Oargc) {
+		if (i->op == Oarg) {
 			r = newtmp("abi", Kl, fn);
 			emit(Ostorel, 0, R, i->arg[0], r);
 			emit(Oadd, Kl, r, TMP(SP), getcon(off, fn));
-		} else
+		}
+		if (i->op == Oargc)
 			blit(TMP(SP), off, i->arg[1], c->size, fn);
 		off += c->size;
 	}
@@ -675,7 +681,6 @@ arm64_abi(Fn *fn)
 				emiti(*i);
 				break;
 			case Ocall:
-			case Ovacall:
 				for (i0=i; i0>b->ins; i0--)
 					if (!isarg((i0-1)->op))
 						break;