cmd/5l, cmd/6l, cmd/8l: accept PCDATA instruction in input

The portable code in cmd/ld already knows how to process it,
we just have to ignore it during code generation.

R=ken2
CC=golang-dev
https://golang.org/cl/11363043

src/cmd/5l/noop.c

@@ -58,6 +58,7 @@ noops(void)
 {
 	Prog *p, *q, *q1, *q2;
 	int o;
+	int32 arg;
 	Prog *pmorestack;
 	Sym *symmorestack;
 
@@ -272,7 +273,12 @@ noops(void)
 					p->as = AMOVW;
 					p->scond = C_SCOND_LS;
 					p->from.type = D_CONST;
-					p->from.offset = (cursym->text->to.offset2 + 3) & ~3;
+					arg = cursym->text->to.offset2;
+					if(arg == 1) // special marker for known 0
+						arg = 0;
+					if(arg&3)
+						diag("misaligned argument size in stack split");
+					p->from.offset = arg;
 					p->to.type = D_REG;
 					p->to.reg = 2;
 	

src/cmd/5l/optab.c

@@ -246,6 +246,8 @@ Optab	optab[] =
 	{ AMULAWT,	C_REG,	C_REG,	C_REGREG2,		99, 4, 0 },
 
 	{ AUSEFIELD,	C_ADDR,	C_NONE,	C_NONE, 	 0, 0, 0 },
+	{ APCDATA,	C_LCON,	C_NONE,	C_LCON,		0, 0, 0 },
+	{ AFUNCDATA,	C_LCON,	C_NONE,	C_ADDR,	0, 0, 0 },
 
 	{ AXXX,		C_NONE,	C_NONE,	C_NONE,		 0, 4, 0 },
 };

src/cmd/5l/span.c

@@ -141,7 +141,7 @@ span(void)
 				if(checkpool(op, p->as == ACASE ? casesz(p) : m))
 					c = p->pc = scan(op, p, c);
 			}
-			if(m == 0) {
+			if(m == 0 && (p->as != AFUNCDATA && p->as != APCDATA)) {
 				diag("zero-width instruction\n%P", p);
 				continue;
 			}
@@ -211,7 +211,7 @@ span(void)
 				}
  */
 				m = o->size;
-				if(m == 0) {
+				if(m == 0 && (p->as != AFUNCDATA && p->as != APCDATA)) {
 					if(p->as == ATEXT) {
 						autosize = p->to.offset + 4;
 						if(p->from.sym != S)
@@ -890,6 +890,8 @@ buildop(void)
 		case APLD:
 		case AUNDEF:
 		case ACLZ:
+		case AFUNCDATA:
+		case APCDATA:
 			break;
 		}
 	}

src/cmd/6l/optab.c

@@ -53,6 +53,16 @@ uchar	ynop[] =
 	Yxr,	Ynone,	Zpseudo,1,
 	0
 };
+uchar	yfuncdata[] =
+{
+	Yi32,	Ym,	Zpseudo,	0,
+	0
+};
+uchar	ypcdata[] = 
+{
+	Yi32,	Yi32,	Zpseudo,	0,
+	0
+};
 uchar	yxorb[] =
 {
 	Yi32,	Yal,	Zib_,	1,
@@ -1342,8 +1352,8 @@ Optab optab[] =
 	{ APCLMULQDQ,	yxshuf,	Pq, 0x3a,0x44,0 },
 
 	{ AUSEFIELD,	ynop,	Px, 0,0 },
-	{ AFUNCDATA,	ynop,	Px, 0,0 },
-	{ APCDATA,	ynop,	Px, 0,0 },
+	{ AFUNCDATA,	yfuncdata,	Px, 0,0 },
+	{ APCDATA,	ypcdata,	Px, 0,0 },
 
 	{ AEND },
 	0

src/cmd/6l/pass.c

@@ -589,7 +589,10 @@ dostkoff(void)
 			if(StackTop + textarg + PtrSize + autoffset + PtrSize + StackLimit >= StackMin)
 				moreconst1 = autoffset;
 			moreconst2 = textarg;
-
+			if(moreconst2 == 1) // special marker
+				moreconst2 = 0;
+			if((moreconst2&7) != 0)
+				diag("misaligned argument size in stack split");
 			// 4 varieties varieties (const1==0 cross const2==0)
 			// and 6 subvarieties of (const1==0 and const2!=0)
 			p = appendp(p);

src/cmd/8l/optab.c

@@ -49,6 +49,16 @@ uchar	ynop[] =
 	Yrf,	Ynone,	Zpseudo,1,
 	0
 };
+uchar	yfuncdata[] =
+{
+	Yi32,	Ym,	Zpseudo,	0,
+	0
+};
+uchar	ypcdata[] =
+{
+	Yi32,	Yi32,	Zpseudo,	0,
+	0,
+};
 uchar	yxorb[] =
 {
 	Yi32,	Yal,	Zib_,	1,
@@ -1002,8 +1012,8 @@ Optab optab[] =
 
 	{ AUSEFIELD,	ynop,	Px, 0,0 },
 	{ ATYPE },
-	{ AFUNCDATA,	ynop,	Px, 0,0 },
-	{ APCDATA,	ynop,	Px, 0,0 },
+	{ AFUNCDATA,	yfuncdata,	Px, 0,0 },
+	{ APCDATA,	ypcdata,	Px, 0,0 },
 
 	0
 };

src/cmd/8l/pass.c

@@ -410,7 +410,7 @@ dostkoff(void)
 {
 	Prog *p, *q, *q1;
 	int32 autoffset, deltasp;
-	int a;
+	int a, arg;
 	Prog *pmorestack;
 	Sym *symmorestack;
 	Sym *plan9_tos;
@@ -623,11 +623,16 @@ dostkoff(void)
 			if(StackTop + cursym->text->to.offset2 + PtrSize + autoffset + PtrSize + StackLimit >= StackMin)
 				p->from.offset = (autoffset+7) & ~7LL;
 
+			arg = cursym->text->to.offset2;
+			if(arg == 1) // special marker for known 0
+				arg = 0;
+			if(arg&3)
+				diag("misaligned argument size in stack split");
 			p = appendp(p);	// save arg size in AX
 			p->as = AMOVL;
 			p->to.type = D_AX;
 			p->from.type = D_CONST;
-			p->from.offset = cursym->text->to.offset2;
+			p->from.offset = arg;
 
 			p = appendp(p);
 			p->as = ACALL;