cosmetics in sysv abi

A struct of size 0 is now marked as passed in memory.
All the ABI code assumes structs passed in registers
have size at least 8.  This could have an impact on
the alignment in the stack, but eh, I guess they are
rare.

1 files changed, 9 insertions, 11 deletions

diff --git a/sysv.c b/sysv.c
index e0571e9..404c0ac 100644
--- a/sysv.c
+++ b/sysv.c
@@ -37,7 +37,7 @@ aclass(AClass *a, Typ *t)
 	a->size = sz;
 	a->align = t->align;
 
-	if (t->dark || sz > 16) {
+	if (t->dark || sz > 16 || sz == 0) {
 		/* large or unaligned structures are
 		 * required to be passed in memory
 		 */
@@ -265,7 +265,7 @@ selcall(Fn *fn, Ins *i0, Ins *i1, RAlloc **rap)
 	AClass *ac, *a, aret;
 	int ca, ni, ns, al;
 	uint stk, off;
-	Ref r, r1, r2, reg[2], regcp[2];
+	Ref r, r1, r2, reg[2];
 	RAlloc *ra;
 
 	ac = alloc((i1-i0) * sizeof ac[0]);
@@ -299,18 +299,16 @@ selcall(Fn *fn, Ins *i0, Ins *i1, RAlloc **rap)
 		} else {
 			if (aret.size > 8) {
 				r = newtmp("abi", Kl, fn);
-				regcp[1] = newtmp("abi", aret.cls[1], fn);
-				emit(OStorel, 0, R, regcp[1], r);
+				aret.ref[1] = newtmp("abi", aret.cls[1], fn);
+				emit(OStorel, 0, R, aret.ref[1], r);
 				emit(OAdd, Kl, r, i1->to, getcon(8, fn));
-				ca += 1 << (2 * KBASE(aret.cls[1]));
 			}
-			regcp[0] = newtmp("abi", aret.cls[0], fn);
-			emit(OStorel, 0, R, regcp[0], i1->to);
-			ca += 1 << (2 * KBASE(aret.cls[0]));
-			retr(reg, &aret);
+			aret.ref[0] = newtmp("abi", aret.cls[0], fn);
+			emit(OStorel, 0, R, aret.ref[0], i1->to);
+			ca += retr(reg, &aret);
 			if (aret.size > 8)
-				emit(OCopy, aret.cls[1], regcp[1], reg[1], R);
-			emit(OCopy, aret.cls[0], regcp[0], reg[0], R);
+				emit(OCopy, aret.cls[1], aret.ref[1], reg[1], R);
+			emit(OCopy, aret.cls[0], aret.ref[0], reg[0], R);
 			r1 = i1->to;
 		}
 		/* allocate return pad */