qbe

commit f71206500c6693eed4393d72e8ab95d6a7e07d98
parent 62c275fc75737e06844a89310bd18eccfbdfa573
Author: Quentin Carbonneaux <quentin.carbonneaux@yale.edu>
Date:   Mon,  4 Apr 2016 11:34:26 -0400

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.

Diffstat:
M
sysv.c
 | 
20
+++++++++-----------

1 file changed, 9 insertions(+), 11 deletions(-)
diff --git 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 */