rv64: plug holes in the abi

Many things got fixed, but the most
notable change is the proper support
of floating point types in aggregates.

Minor fixes:
- selpar() did not deal correctly
  with Cfpint
- typclass() was reading out of
  bounds in the gp/fp arrays
- support for env calls

1 files changed, 196 insertions, 149 deletions

diff --git a/rv64/abi.c b/rv64/abi.c
index b49057b..ddcba9d 100644
--- a/rv64/abi.c
+++ b/rv64/abi.c
@@ -1,5 +1,7 @@
 #include "all.h"
 
+/* the risc-v lp64d abi */
+
 typedef struct Class Class;
 typedef struct Insl Insl;
 typedef struct Params Params;
@@ -14,13 +16,13 @@ enum {
 
 struct Class {
 	char class;
-	uint size;
-	Typ *t;
-	uchar nreg;
-	uchar ngp;
-	uchar nfp;
+	Typ *type;
 	int reg[2];
 	int cls[2];
+	int off[2];
+	char ngp; /* only valid after typclass() */
+	char nfp; /* ditto */
+	char nreg;
 };
 
 struct Insl {
@@ -34,17 +36,18 @@ struct Params {
 	int stk; /* stack offset for varargs */
 };
 
-static int gpreg[] = { A0,  A1,  A2,  A3,  A4,  A5,  A6,  A7};
-static int fpreg[] = {FA0, FA1, FA2, FA3, FA4, FA5, FA6, FA7};
+static int gpreg[10] = {A0, A1, A2, A3, A4, A5, A6, A7};
+static int fpreg[10] = {FA0, FA1, FA2, FA3, FA4, FA5, FA6, FA7};
 
 /* layout of call's second argument (RCall)
  *
- *  29       8    4  2  0
- *  |0.00|xxxx|xxxx|xx|xx|                  range
- *           |    |  |  ` gp regs returned (0..2)
- *           |    |  ` fp regs returned    (0..2)
- *           |    ` gp regs passed         (0..8)
- *            ` fp regs passed             (0..8)
+ *  29   12    8    4  2  0
+ *  |0.00|x|xxxx|xxxx|xx|xx|                  range
+ *        |   |    |  |  ` gp regs returned (0..2)
+ *        |   |    |  ` fp regs returned    (0..2)
+ *        |   |    ` gp regs passed         (0..8)
+ *        |    ` fp regs passed             (0..8)
+ *        ` env pointer passed in t5        (0..1)
  */
 
 bits
@@ -72,12 +75,12 @@ bits
 rv64_argregs(Ref r, int p[2])
 {
 	bits b;
-	int ngp, nfp;
+	int ngp, nfp, t5;
 
 	assert(rtype(r) == RCall);
 	ngp = (r.val >> 4) & 15;
 	nfp = (r.val >> 8) & 15;
-	b = 0;
+	t5 = (r.val >> 12) & 1;
 	if (p) {
 		p[0] = ngp;
 		p[1] = nfp;
@@ -87,17 +90,52 @@ rv64_argregs(Ref r, int p[2])
 		b |= BIT(A0+ngp);
 	while (nfp--)
 		b |= BIT(FA0+nfp);
-	return b;
+	return b | ((bits)t5 << T5);
+}
+
+static int
+fpstruct(Typ *t, int off, Class *c)
+{
+	Field *f;
+	int n;
+
+	if (t->isunion)
+		return -1;
+
+	for (f=*t->fields; f->type != FEnd; f++)
+		if (f->type == FPad)
+			off += f->len;
+		else if (f->type == FTyp) {
+			if (fpstruct(&typ[f->len], off, c) == -1)
+				return -1;
+		}
+		else {
+			n = c->nfp + c->ngp;
+			if (n == 2)
+				return -1;
+			switch (f->type) {
+			default: die("unreachable");
+			case Fb:
+			case Fh:
+			case Fw: c->cls[n] = Kw; c->ngp++; break;
+			case Fl: c->cls[n] = Kl; c->ngp++; break;
+			case Fs: c->cls[n] = Ks; c->nfp++; break;
+			case Fd: c->cls[n] = Kd; c->nfp++; break;
+			}
+			c->off[n] = off;
+			off += f->len;
+		}
+
+	return c->nfp;
 }
 
 static void
-typclass(Class *c, Typ *t, int *gp, int *fp)
+typclass(Class *c, Typ *t, int fpabi, int *gp, int *fp)
 {
-	uint64_t sz;
 	uint n;
+	int i;
 
-	sz = (t->size + 7) & ~7;
-	c->t = t;
+	c->type = t;
 	c->class = 0;
 	c->ngp = 0;
 	c->nfp = 0;
@@ -105,63 +143,63 @@ typclass(Class *c, Typ *t, int *gp, int *fp)
 	if (t->align > 4)
 		err("alignments larger than 16 are not supported");
 
-	if (t->isdark || sz > 16 || sz == 0) {
+	if (t->isdark || t->size > 16 || t->size == 0) {
 		/* large structs are replaced by a
 		 * pointer to some caller-allocated
-		 * memory */
+		 * memory
+		 */
 		c->class |= Cptr;
-		c->size = 8;
-		return;
+		*c->cls = Kl;
+		*c->off = 0;
+		c->ngp = 1;
 	}
-
-	c->size = sz;
-
-	/* TODO: float */
-	(void)fp;
-
-	for (n=0; n<sz/8; n++, c->ngp++) {
-		c->reg[n] = *gp++;
-		c->cls[n] = Kl;
+	else if (!fpabi || fpstruct(t, 0, c) <= 0) {
+		for (n=0; 8*n<t->size; n++) {
+			c->cls[n] = Kl;
+			c->off[n] = 8*n;
+		}
+		c->nfp = 0;
+		c->ngp = n;
 	}
 
-	c->nreg = n;
+	c->nreg = c->nfp + c->ngp;
+	for (i=0; i<c->nreg; i++)
+		if (KBASE(c->cls[i]) == 0)
+			c->reg[i] = *gp++;
+		else
+			c->reg[i] = *fp++;
 }
 
 static void
-sttmps(Ref tmp[], int cls[], uint nreg, Ref mem, Fn *fn)
+sttmps(Ref tmp[], int ntmp, Class *c, Ref mem, Fn *fn)
 {
 	static int st[] = {
 		[Kw] = Ostorew, [Kl] = Ostorel,
 		[Ks] = Ostores, [Kd] = Ostored
 	};
-	uint n;
-	uint64_t off;
+	int i;
 	Ref r;
 
-	assert(nreg <= 4);
-	off = 0;
-	for (n=0; n<nreg; n++) {
-		tmp[n] = newtmp("abi", cls[n], fn);
+	assert(ntmp > 0);
+	assert(ntmp <= 2);
+	for (i=0; i<ntmp; i++) {
+		tmp[i] = newtmp("abi", c->cls[i], fn);
 		r = newtmp("abi", Kl, fn);
-		emit(st[cls[n]], 0, R, tmp[n], r);
-		emit(Oadd, Kl, r, mem, getcon(off, fn));
-		off += KWIDE(cls[n]) ? 8 : 4;
+		emit(st[c->cls[i]], 0, R, tmp[i], r);
+		emit(Oadd, Kl, r, mem, getcon(c->off[i], fn));
 	}
 }
 
 static void
-ldregs(int reg[], int cls[], int n, Ref mem, Fn *fn)
+ldregs(Class *c, Ref mem, Fn *fn)
 {
 	int i;
-	uint64_t off;
 	Ref r;
 
-	off = 0;
-	for (i=0; i<n; i++) {
+	for (i=0; i<c->nreg; i++) {
 		r = newtmp("abi", Kl, fn);
-		emit(Oload, cls[i], TMP(reg[i]), r, R);
-		emit(Oadd, Kl, r, mem, getcon(off, fn));
-		off += KWIDE(cls[i]) ? 8 : 4;
+		emit(Oload, c->cls[i], TMP(c->reg[i]), r, R);
+		emit(Oadd, Kl, r, mem, getcon(c->off[i], fn));
 	}
 }
 
@@ -181,13 +219,13 @@ selret(Blk *b, Fn *fn)
 	b->jmp.type = Jret0;
 
 	if (j == Jretc) {
-		typclass(&cr, &typ[fn->retty], gpreg, fpreg);
+		typclass(&cr, &typ[fn->retty], 1, gpreg, fpreg);
 		cty = (cr.nfp << 2) | cr.ngp;
 		if (cr.class & Cptr) {
 			assert(rtype(fn->retr) == RTmp);
-			blit0(fn->retr, r, cr.t->size, fn);
+			blit0(fn->retr, r, cr.type->size, fn);
 		} else {
-			ldregs(cr.reg, cr.cls, cr.nreg, r, fn);
+			ldregs(&cr, r, fn);
 		}
 	} else {
 		k = j - Jretw;
@@ -204,10 +242,11 @@ selret(Blk *b, Fn *fn)
 }
 
 static int
-argsclass(Ins *i0, Ins *i1, Class *carg, Ref *env, int retptr)
+argsclass(Ins *i0, Ins *i1, Class *carg, int retptr)
 {
-	int ngp, nfp, *gp, *fp, vararg;
+	int ngp, nfp, *gp, *fp, vararg, envc;
 	Class *c;
+	Typ *t;
 	Ins *i;
 
 	gp = gpreg;
@@ -215,6 +254,7 @@ argsclass(Ins *i0, Ins *i1, Class *carg, Ref *env, int retptr)
 	ngp = 8;
 	nfp = 8;
 	vararg = 0;
+	envc = 0;
 	if (retptr) {
 		gp++;
 		ngp--;
@@ -224,8 +264,6 @@ argsclass(Ins *i0, Ins *i1, Class *carg, Ref *env, int retptr)
 		case Opar:
 		case Oarg:
 			*c->cls = i->cls;
-			c->size = 8;
-			/* variadic float args are passed in int regs */
 			if (!vararg && KBASE(i->cls) == 1 && nfp > 0) {
 				nfp--;
 				*c->reg = *fp++;
@@ -234,63 +272,62 @@ argsclass(Ins *i0, Ins *i1, Class *carg, Ref *env, int retptr)
 					c->class |= Cfpint;
 				ngp--;
 				*c->reg = *gp++;
-			} else {
+			} else
 				c->class |= Cstk1;
-			}
 			break;
 		case Oargv:
-			/* subsequent arguments are variadic */
 			vararg = 1;
 			break;
 		case Oparc:
 		case Oargc:
-			typclass(c, &typ[i->arg[0].val], gp, fp);
-			if (c->class & Cptr) {
-				c->ngp = 1;
-				*c->reg = *gp;
-				*c->cls = Kl;
-			}
-			if (c->ngp <= ngp && c->nfp <= nfp) {
+			t = &typ[i->arg[0].val];
+			typclass(c, t, 1, gp, fp);
+			if (c->nfp > 0)
+			if (c->nfp >= nfp || c->ngp >= ngp)
+				typclass(c, t, 0, gp, fp);
+			assert(c->nfp <= nfp);
+			if (c->ngp <= ngp) {
 				ngp -= c->ngp;
 				nfp -= c->nfp;
 				gp += c->ngp;
 				fp += c->nfp;
-				break;
-			}
-			c->ngp += c->nfp;
-			c->nfp = 0;
-			if (c->ngp <= ngp) {
-				ngp -= c->ngp;
-				gp += c->ngp;
-				break;
-			}
-			c->class |= Cstk1;
-			if (c->ngp - 1 > ngp)
+			} else if (ngp > 0) {
+				assert(c->ngp == 2);
+				assert(c->class == 0);
 				c->class |= Cstk2;
+				c->nreg = 1;
+				ngp--;
+				gp++;
+			} else {
+				c->class |= Cstk1;
+				if (c->nreg > 1)
+					c->class |= Cstk2;
+				c->nreg = 0;
+			}
 			break;
 		case Opare:
-			*env = i->to;
-			break;
 		case Oarge:
-			*env = i->arg[0];
+			*c->cls = Kl;
+			*c->reg = T5;
+			envc = 1;
 			break;
 		}
 	}
-	return (gp-gpreg) << 4 | (fp-fpreg) << 8;
+	return envc << 12 | (gp-gpreg) << 4 | (fp-fpreg) << 8;
 }
 
 static void
-stkblob(Ref r, Class *c, Fn *fn, Insl **ilp)
+stkblob(Ref r, Typ *t, Fn *fn, Insl **ilp)
 {
 	Insl *il;
 	int al;
 	uint64_t sz;
 
 	il = alloc(sizeof *il);
-	al = c->t->align - 2; /* NAlign == 3 */
+	al = t->align - 2; /* specific to NAlign == 3 */
 	if (al < 0)
 		al = 0;
-	sz = c->class & Cptr ? c->t->size : c->size;
+	sz = (t->size + 7) & ~7;
 	il->i = (Ins){Oalloc+al, Kl, r, {getcon(sz, fn)}};
 	il->link = *ilp;
 	*ilp = il;
@@ -301,26 +338,24 @@ selcall(Fn *fn, Ins *i0, Ins *i1, Insl **ilp)
 {
 	Ins *i;
 	Class *ca, *c, cr;
-	int k, cty, envc;
-	uint n;
+	int j, k, cty;
 	uint64_t stk, off;
-	Ref r, r1, env, tmp[2];
+	Ref r, r1, tmp[2];
 
-	env = R;
 	ca = alloc((i1-i0) * sizeof ca[0]);
 	cr.class = 0;
 
 	if (!req(i1->arg[1], R))
-		typclass(&cr, &typ[i1->arg[1].val], gpreg, fpreg);
+		typclass(&cr, &typ[i1->arg[1].val], 1, gpreg, fpreg);
 
-	cty = argsclass(i0, i1, ca, &env, cr.class & Cptr);
+	cty = argsclass(i0, i1, ca, cr.class & Cptr);
 	stk = 0;
 	for (i=i0, c=ca; i<i1; i++, c++) {
 		if (i->op == Oargv)
 			continue;
 		if (c->class & Cptr) {
 			i->arg[0] = newtmp("abi", Kl, fn);
-			stkblob(i->arg[0], c, fn, ilp);
+			stkblob(i->arg[0], c->type, fn, ilp);
 			i->op = Oarg;
 		}
 		if (c->class & Cstk1)
@@ -328,20 +363,24 @@ selcall(Fn *fn, Ins *i0, Ins *i1, Insl **ilp)
 		if (c->class & Cstk2)
 			stk += 8;
 	}
+	stk += stk & 15;
 	if (stk)
 		emit(Osalloc, Kl, R, getcon(-stk, fn), R);
 
 	if (!req(i1->arg[1], R)) {
-		stkblob(i1->to, &cr, fn, ilp);
+		stkblob(i1->to, cr.type, fn, ilp);
 		cty |= (cr.nfp << 2) | cr.ngp;
-		if (cr.class & Cptr) {
-			cty |= 1;
+		if (cr.class & Cptr)
+			/* spill & rega expect calls to be
+			 * followed by copies from regs,
+			 * so we emit a dummy
+			 */
 			emit(Ocopy, Kw, R, TMP(A0), R);
-		} else {
-			sttmps(tmp, cr.cls, cr.nreg, i1->to, fn);
-			for (n=0; n<cr.nreg; n++) {
-				r = TMP(cr.reg[n]);
-				emit(Ocopy, cr.cls[n], tmp[n], r, R);
+		else {
+			sttmps(tmp, cr.nreg, &cr, i1->to, fn);
+			for (j=0; j<cr.nreg; j++) {
+				r = TMP(cr.reg[j]);
+				emit(Ocopy, cr.cls[j], tmp[j], r, R);
 			}
 		}
 	} else if (KBASE(i1->cls) == 0) {
@@ -352,9 +391,6 @@ selcall(Fn *fn, Ins *i0, Ins *i1, Insl **ilp)
 		cty |= 1 << 2;
 	}
 
-	envc = !req(R, env);
-	if (envc)
-		die("todo: env calls");
 	emit(Ocall, 0, R, i1->arg[0], CALL(cty));
 
 	if (cr.class & Cptr)
@@ -366,7 +402,7 @@ selcall(Fn *fn, Ins *i0, Ins *i1, Insl **ilp)
 		if (i->op == Oargv || c->class & Cstk1)
 			continue;
 		if (i->op == Oargc) {
-			ldregs(c->reg, c->cls, c->nreg, i->arg[1], fn);
+			ldregs(c, i->arg[1], fn);
 		} else if (c->class & Cfpint) {
 			k = KWIDE(*c->cls) ? Kl : Kw;
 			r = newtmp("abi", k, fn);
@@ -383,7 +419,7 @@ selcall(Fn *fn, Ins *i0, Ins *i1, Insl **ilp)
 			emit(Ocast, k, TMP(*c->reg), i->arg[0], R);
 		}
 		if (c->class & Cptr)
-			blit0(i->arg[0], i->arg[1], c->t->size, fn);
+			blit0(i->arg[0], i->arg[1], c->type->size, fn);
 	}
 
 	if (!stk)
@@ -391,36 +427,33 @@ selcall(Fn *fn, Ins *i0, Ins *i1, Insl **ilp)
 
 	r = newtmp("abi", Kl, fn);
 	for (i=i0, c=ca, off=0; i<i1; i++, c++) {
-		if (i->op == Oargv || (c->class & Cstk) == 0)
+		if (i->op == Oargv || !(c->class & Cstk))
 			continue;
-		if (i->op != Oargc) {
-			/* w arguments are stored sign-extended
-			 * to 64-bits
-			 *
-			 * s arguments can just be stored with
-			 * Ostores into the first 32-bits in the
-			 * stack position since the ABI says the
-			 * upper bits are undefined
-			 */
+		if (i->op == Oarg) {
 			r1 = newtmp("abi", Kl, fn);
 			emit(Ostorew+i->cls, Kw, R, i->arg[0], r1);
 			if (i->cls == Kw) {
 				/* TODO: we only need this sign extension
 				 * for subtyped l temporaries passed as w
 				 * arguments (see rv64/isel.c:fixarg)
-				 *
-				 * however, we cannot just fix it in isel
-				 * since by that point we have forgotten
-				 * the original argument type
 				 */
 				curi->op = Ostorel;
 				curi->arg[0] = newtmp("abi", Kl, fn);
 				emit(Oextsw, Kl, curi->arg[0], i->arg[0], R);
 			}
 			emit(Oadd, Kl, r1, r, getcon(off, fn));
-		} else
-			blit(r, off, i->arg[1], 0, c->t->size, fn);
-		off += c->size;
+			off += 8;
+		}
+		if (i->op == Oargc) {
+			if (c->class & Cstk1) {
+				blit(r, off, i->arg[1], 0, 8, fn);
+				off += 8;
+			}
+			if (c->class & Cstk2) {
+				blit(r, off, i->arg[1], 8, 8, fn);
+				off += 8;
+			}
+		}
 	}
 	emit(Osalloc, Kl, r, getcon(stk, fn), R);
 }
@@ -431,60 +464,74 @@ selpar(Fn *fn, Ins *i0, Ins *i1)
 	Class *ca, *c, cr;
 	Insl *il;
 	Ins *i;
-	int n, s, cty;
-	Ref r, env, tmp[16], *t;
+	int j, k, s, cty, nt;
+	Ref r, tmp[17], *t;
 
-	env = R;
 	ca = alloc((i1-i0) * sizeof ca[0]);
 	cr.class = 0;
 	curi = &insb[NIns];
 
 	if (fn->retty >= 0) {
-		typclass(&cr, &typ[fn->retty], gpreg, fpreg);
+		typclass(&cr, &typ[fn->retty], 1, gpreg, fpreg);
 		if (cr.class & Cptr) {
 			fn->retr = newtmp("abi", Kl, fn);
 			emit(Ocopy, Kl, fn->retr, TMP(A0), R);
 		}
 	}
 
-	cty = argsclass(i0, i1, ca, &env, cr.class & Cptr);
+	cty = argsclass(i0, i1, ca, cr.class & Cptr);
 	fn->reg = rv64_argregs(CALL(cty), 0);
 
 	il = 0;
 	t = tmp;
 	for (i=i0, c=ca; i<i1; i++, c++) {
-		if (i->op != Oparc || (c->class & (Cptr|Cstk)))
-			continue;
-		sttmps(t, c->cls, c->nreg, i->to, fn);
-		stkblob(i->to, c, fn, &il);
-		t += c->nreg;
+		if (c->class & Cfpint) {
+			r = i->to;
+			k = *c->cls;
+			*c->cls = KWIDE(k) ? Kl : Kw;
+			i->to = newtmp("abi", k, fn);
+			emit(Ocast, k, r, i->to, R);
+		}
+		if (i->op == Oparc)
+		if (!(c->class & Cptr))
+		if (c->nreg != 0) {
+			nt = c->nreg;
+			if (c->class & Cstk2) {
+				c->cls[1] = Kl;
+				c->off[1] = 8;
+				assert(nt == 1);
+				nt = 2;
+			}
+			sttmps(t, nt, c, i->to, fn);
+			stkblob(i->to, c->type, fn, &il);
+			t += nt;
+		}
 	}
 	for (; il; il=il->link)
 		emiti(il->i);
 
 	t = tmp;
-	for (i=i0, c=ca, s=2 + 8 * fn->vararg; i<i1; i++, c++) {
-		if (i->op == Oparc
-		&& (c->class & Cptr) == 0) {
-			if (c->class & Cstk) {
+	s = 2 + 8*fn->vararg;
+	for (i=i0, c=ca; i<i1; i++, c++)
+		if (i->op == Oparc && !(c->class & Cptr)) {
+			if (c->nreg == 0) {
 				fn->tmp[i->to.val].slot = -s;
-				s += c->size / 8;
-			} else {
-				for (n=0; n<c->nreg; n++) {
-					r = TMP(c->reg[n]);
-					emit(Ocopy, c->cls[n], *t++, r, R);
-				}
+				s += (c->class & Cstk2) ? 2 : 1;
+				continue;
+			}
+			for (j=0; j<c->nreg; j++) {
+				r = TMP(c->reg[j]);
+				emit(Ocopy, c->cls[j], *t++, r, R);
+			}
+			if (c->class & Cstk2) {
+				emit(Oload, Kl, *t, SLOT(-s), R);
+				t++, s++;
 			}
 		} else if (c->class & Cstk1) {
 			emit(Oload, *c->cls, i->to, SLOT(-s), R);
 			s++;
-		} else {
+		} else
 			emit(Ocopy, *c->cls, i->to, TMP(*c->reg), R);
-		}
-	}
-
-	if (!req(R, env))
-		die("todo: env calls");
 
 	return (Params){
 		.stk = s,