cmd/ld: avoid redundant external relocation calculations

R=ken2, ken
CC=golang-dev
https://golang.org/cl/7483045

src/cmd/5l/asm.c

@@ -240,12 +240,13 @@ adddynrel(Sym *s, Reloc *r)
 }
 
 int
-elfreloc1(Reloc *r, vlong off, int32 elfsym, vlong add)
+elfreloc1(Reloc *r, vlong sectoff)
 {
-	USED(add);	// written to obj file by ../ld/data.c's reloc
-
-	LPUT(off);
+	int32 elfsym;
+	
+	LPUT(sectoff);
 
+	elfsym = r->xsym->elfsym;
 	switch(r->type) {
 	default:
 		return -1;

src/cmd/5l/l.h

@@ -96,9 +96,12 @@ struct	Reloc
 {
 	int32	off;
 	uchar	siz;
+	uchar	done;
 	int16	type;
 	int32	add;
+	int32	xadd;
 	Sym*	sym;
+	Sym*	xsym;
 };
 
 struct	Prog

src/cmd/6l/asm.c

@@ -284,10 +284,13 @@ adddynrel(Sym *s, Reloc *r)
 }
 
 int
-elfreloc1(Reloc *r, vlong off, int32 elfsym, vlong add)
+elfreloc1(Reloc *r, vlong sectoff)
 {
-	VPUT(off);
+	int32 elfsym;
 
+	VPUT(sectoff);
+
+	elfsym = r->xsym->elfsym;
 	switch(r->type) {
 	default:
 		return -1;
@@ -306,11 +309,10 @@ elfreloc1(Reloc *r, vlong off, int32 elfsym, vlong add)
 			VPUT(R_X86_64_PC32 | (uint64)elfsym<<32);
 		else
 			return -1;
-		add -= r->siz;
 		break;
 	}
 
-	VPUT(add);
+	VPUT(r->xadd);
 	return 0;
 }
 

src/cmd/6l/l.h

@@ -101,9 +101,12 @@ struct	Reloc
 {
 	int32	off;
 	uchar	siz;
+	uchar	done;
 	int32	type;
 	int64	add;
+	int64	xadd;
 	Sym*	sym;
+	Sym*	xsym;
 };
 
 struct	Prog

src/cmd/8l/asm.c

@@ -270,12 +270,13 @@ adddynrel(Sym *s, Reloc *r)
 }
 
 int
-elfreloc1(Reloc *r, vlong off, int32 elfsym, vlong add)
+elfreloc1(Reloc *r, vlong sectoff)
 {
-	USED(add);	// written to obj file by ../ld/data.c's reloc
+	int32 elfsym;
 
-	LPUT(off);
+	LPUT(sectoff);
 
+	elfsym = r->xsym->elfsym;
 	switch(r->type) {
 	default:
 		return -1;

src/cmd/8l/l.h

@@ -84,9 +84,12 @@ struct	Reloc
 {
 	int32	off;
 	uchar	siz;
+	uchar	done;
 	int32	type;
 	int32	add;
+	int32	xadd;
 	Sym*	sym;
+	Sym*	xsym;
 };
 
 struct	Prog

src/cmd/ld/data.c

@@ -155,6 +155,7 @@ relocsym(Sym *s)
 	cursym = s;
 	memset(&p, 0, sizeof p);
 	for(r=s->r; r<s->r+s->nr; r++) {
+		r->done = 1;
 		off = r->off;
 		siz = r->siz;
 		if(off < 0 || off+siz > s->np) {
@@ -181,31 +182,51 @@ relocsym(Sym *s)
 				diag("unknown reloc %d", r->type);
 			break;
 		case D_ADDR:
-			o = symaddr(r->sym) + r->add;
 			if(isobj && r->sym->type != SCONST) {
+				r->done = 0;
+
+				// set up addend for eventual relocation via outer symbol.
+				rs = r->sym;
+				r->xadd = r->add;
+				while(rs->outer != nil) {
+					r->xadd += symaddr(rs) - symaddr(rs->outer);
+					rs = rs->outer;
+				}
+				r->xsym = rs;
+
 				if(thechar == '6')
 					o = 0;
-				else {
-					// set up addend for eventual relocation via outer symbol
-					rs = r->sym;
-					while(rs->outer != nil)
-						rs = rs->outer;
-					o -= symaddr(rs);
-				}
+				else
+					o = r->xadd;
+				break;
 			}
+			o = symaddr(r->sym) + r->add;
 			break;
 		case D_PCREL:
 			// r->sym can be null when CALL $(constant) is transformed from absolute PC to relative PC call.
-			o = 0;
-			if(r->sym)
-				o += symaddr(r->sym);
-			o += r->add - (s->value + r->off + r->siz);
-			if(isobj && r->sym->type != SCONST && r->sym->sect != cursym->sect) {
+			if(isobj && r->sym && r->sym->type != SCONST && r->sym->sect != cursym->sect) {
+				r->done = 0;
+
+				// set up addend for eventual relocation via outer symbol.
+				rs = r->sym;
+				r->xadd = r->add;
+				while(rs->outer != nil) {
+					r->xadd += symaddr(rs) - symaddr(rs->outer);
+					rs = rs->outer;
+				}
+				r->xsym = rs;
+				r->xadd -= r->siz;
+
 				if(thechar == '6')
 					o = 0;
 				else
-					o = r->add - r->siz;
+					o = r->xadd;
+				break;
 			}
+			o = 0;
+			if(r->sym)
+				o += symaddr(r->sym);
+			o += r->add - (s->value + r->off + r->siz);
 			break;
 		case D_SIZE:
 			o = r->sym->size + r->add;

src/cmd/ld/elf.c

@@ -805,10 +805,9 @@ elfshreloc(Section *sect)
 void
 elfrelocsect(Section *sect, Sym *first)
 {
-	Sym *sym, *rs;
+	Sym *sym;
 	int32 eaddr;
 	Reloc *r;
-	int64 add;
 
 	// If main section is SHT_NOBITS, nothing to relocate.
 	// Also nothing to relocate in .shstrtab.
@@ -834,30 +833,15 @@ elfrelocsect(Section *sect, Sym *first)
 		cursym = sym;
 		
 		for(r = sym->r; r < sym->r+sym->nr; r++) {
-			// Ignore relocations handled by reloc already.
-			switch(r->type) {
-			case D_SIZE:
+			if(r->done)
+				continue;
+			if(r->xsym == nil) {
+				diag("missing xsym in relocation");
 				continue;
-			case D_ADDR:
-			case D_PCREL:
-				if(r->sym->type == SCONST)
-					continue;	// handled in data.c:/^relocsym
-				if(r->type == D_PCREL && r->sym->sect == sym->sect)
-					continue;	// handled in data.c:/^relocsym
-				break;
-			}
-
-			add = r->add;
-			rs = r->sym;
-			while(rs->outer != nil) {
-				add += rs->value - rs->outer->value;
-				rs = rs->outer;
 			}
-				
-			if(rs->elfsym == 0)
-				diag("reloc %d to non-elf symbol %s (rs=%s) %d", r->type, r->sym->name, rs->name, rs->type);
-
-			if(elfreloc1(r, sym->value - sect->vaddr + r->off, rs->elfsym, add) < 0)
+			if(r->xsym->elfsym == 0)
+				diag("reloc %d to non-elf symbol %s (outer=%s) %d", r->type, r->sym->name, r->xsym->name, r->sym->type);
+			if(elfreloc1(r, sym->value+r->off - sect->vaddr) < 0)
 				diag("unsupported obj reloc %d/%d to %s", r->type, r->siz, r->sym->name);
 		}
 	}

src/cmd/ld/elf.h

@@ -1005,7 +1005,7 @@ extern char linuxdynld[];
 extern char freebsddynld[];
 extern char netbsddynld[];
 extern char openbsddynld[];
-int	elfreloc1(Reloc*, vlong off, int32 elfsym, vlong add);
+int	elfreloc1(Reloc*, vlong sectoff);
 
 EXTERN	int	elfstrsize;
 EXTERN	char*	elfstrdat;