cmd/link: fewer allocs in ld.Arch.Archreloc

Archreloc had this signature:

	func(*Link, *sym.Reloc, *sym.Symbol, *int64) bool

The last *int64 argument is used as out parameter.
Passed valus could be allocated on stack, but escape analysis
fails here, leading to high number of unwanted allocs.

If instead 4th arg is passed by value, and modified values is returned,
no problems with allocations arise:

	func(*Link, *sym.Reloc, *sym.Symbol, int64) (int64, bool)

There are 2 benefits:
1. code becomes more readable.
2. less allocations.

For linking "hello world" example from net/http:

	name      old time/op  new time/op  delta
	Linker-4   530ms ± 2%   520ms ± 2%  -1.83%  (p=0.001 n=17+16)

It's top 1 in alloc_objects from memprofile:

	flat   flat%  sum%       cum    cum%
	229379 33.05% 33.05%     229379 33.05%  cmd/link/internal/ld.relocsym
	...

list relocsym:

	229379     229379 (flat, cum) 33.05% of Total
	229379     229379    183:    var o int64

After the patch, ~230k of int64 allocs (~ 1.75mb) removed.

Passes toolshash-check (toolstash cmp).

Change-Id: I25504fe27967bcff70c4b7338790f3921d15473d
Reviewed-on: https://go-review.googlesource.com/113637
Run-TryBot: Iskander Sharipov <iskander.sharipov@intel.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/cmd/link/internal/amd64/asm.go

@@ -532,8 +532,8 @@ func pereloc1(arch *sys.Arch, out *ld.OutBuf, s *sym.Symbol, r *sym.Reloc, secto
 	return true
 }
 
-func archreloc(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val *int64) bool {
+func archreloc(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val int64) (int64, bool) {
-	return false
+	return val, false
 }
 
 func archrelocvariant(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, t int64) int64 {

src/cmd/link/internal/arm/asm.go

@@ -568,7 +568,7 @@ func gentrampdyn(arch *sys.Arch, tramp, target *sym.Symbol, offset int64) {
 	}
 }
 
-func archreloc(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val *int64) bool {
+func archreloc(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val int64) (int64, bool) {
 	if ctxt.LinkMode == ld.LinkExternal {
 		switch r.Type {
 		case objabi.R_CALLARM:
@@ -602,20 +602,17 @@ func archreloc(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val *int64) bool {
 				ld.Errorf(s, "direct call too far %d", r.Xadd/4)
 			}
 
-			*val = int64(braddoff(int32(0xff000000&uint32(r.Add)), int32(0xffffff&uint32(r.Xadd/4))))
+			return int64(braddoff(int32(0xff000000&uint32(r.Add)), int32(0xffffff&uint32(r.Xadd/4)))), true
-			return true
 		}
 
-		return false
+		return -1, false
 	}
 
 	switch r.Type {
 	case objabi.R_CONST:
-		*val = r.Add
+		return r.Add, true
-		return true
 	case objabi.R_GOTOFF:
-		*val = ld.Symaddr(r.Sym) + r.Add - ld.Symaddr(ctxt.Syms.Lookup(".got", 0))
+		return ld.Symaddr(r.Sym) + r.Add - ld.Symaddr(ctxt.Syms.Lookup(".got", 0)), true
-		return true
 
 	// The following three arch specific relocations are only for generation of
 	// Linux/ARM ELF's PLT entry (3 assembler instruction)
@@ -623,16 +620,11 @@ func archreloc(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val *int64) bool {
 		if ld.Symaddr(ctxt.Syms.Lookup(".got.plt", 0)) < ld.Symaddr(ctxt.Syms.Lookup(".plt", 0)) {
 			ld.Errorf(s, ".got.plt should be placed after .plt section.")
 		}
-		*val = 0xe28fc600 + (0xff & (int64(uint32(ld.Symaddr(r.Sym)-(ld.Symaddr(ctxt.Syms.Lookup(".plt", 0))+int64(r.Off))+r.Add)) >> 20))
+		return 0xe28fc600 + (0xff & (int64(uint32(ld.Symaddr(r.Sym)-(ld.Symaddr(ctxt.Syms.Lookup(".plt", 0))+int64(r.Off))+r.Add)) >> 20)), true
-		return true
 	case objabi.R_PLT1: // add ip, ip, #0xYY000
-		*val = 0xe28cca00 + (0xff & (int64(uint32(ld.Symaddr(r.Sym)-(ld.Symaddr(ctxt.Syms.Lookup(".plt", 0))+int64(r.Off))+r.Add+4)) >> 12))
+		return 0xe28cca00 + (0xff & (int64(uint32(ld.Symaddr(r.Sym)-(ld.Symaddr(ctxt.Syms.Lookup(".plt", 0))+int64(r.Off))+r.Add+4)) >> 12)), true
-
-		return true
 	case objabi.R_PLT2: // ldr pc, [ip, #0xZZZ]!
-		*val = 0xe5bcf000 + (0xfff & int64(uint32(ld.Symaddr(r.Sym)-(ld.Symaddr(ctxt.Syms.Lookup(".plt", 0))+int64(r.Off))+r.Add+8)))
+		return 0xe5bcf000 + (0xfff & int64(uint32(ld.Symaddr(r.Sym)-(ld.Symaddr(ctxt.Syms.Lookup(".plt", 0))+int64(r.Off))+r.Add+8))), true
-
-		return true
 	case objabi.R_CALLARM: // bl XXXXXX or b YYYYYY
 		// r.Add is the instruction
 		// low 24-bit encodes the target address
@@ -640,12 +632,10 @@ func archreloc(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val *int64) bool {
 		if t > 0x7fffff || t < -0x800000 {
 			ld.Errorf(s, "direct call too far: %s %x", r.Sym.Name, t)
 		}
-		*val = int64(braddoff(int32(0xff000000&uint32(r.Add)), int32(0xffffff&t)))
+		return int64(braddoff(int32(0xff000000&uint32(r.Add)), int32(0xffffff&t))), true
-
-		return true
 	}
 
-	return false
+	return val, false
 }
 
 func archrelocvariant(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, t int64) int64 {

src/cmd/link/internal/arm64/asm.go

@@ -234,19 +234,19 @@ func machoreloc1(arch *sys.Arch, out *ld.OutBuf, s *sym.Symbol, r *sym.Reloc, se
 	return true
 }
 
-func archreloc(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val *int64) bool {
+func archreloc(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val int64) (int64, bool) {
 	if ctxt.LinkMode == ld.LinkExternal {
 		switch r.Type {
 		default:
-			return false
+			return val, false
 		case objabi.R_ARM64_GOTPCREL:
 			var o1, o2 uint32
 			if ctxt.Arch.ByteOrder == binary.BigEndian {
-				o1 = uint32(*val >> 32)
+				o1 = uint32(val >> 32)
-				o2 = uint32(*val)
+				o2 = uint32(val)
 			} else {
-				o1 = uint32(*val)
+				o1 = uint32(val)
-				o2 = uint32(*val >> 32)
+				o2 = uint32(val >> 32)
 			}
 			// Any relocation against a function symbol is redirected to
 			// be against a local symbol instead (see putelfsym in
@@ -264,9 +264,9 @@ func archreloc(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val *int64) bool {
 				r.Type = objabi.R_ADDRARM64
 			}
 			if ctxt.Arch.ByteOrder == binary.BigEndian {
-				*val = int64(o1)<<32 | int64(o2)
+				val = int64(o1)<<32 | int64(o2)
 			} else {
-				*val = int64(o2)<<32 | int64(o1)
+				val = int64(o2)<<32 | int64(o1)
 			}
 			fallthrough
 		case objabi.R_ADDRARM64:
@@ -294,11 +294,11 @@ func archreloc(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val *int64) bool {
 				var o0, o1 uint32
 
 				if ctxt.Arch.ByteOrder == binary.BigEndian {
-					o0 = uint32(*val >> 32)
+					o0 = uint32(val >> 32)
-					o1 = uint32(*val)
+					o1 = uint32(val)
 				} else {
-					o0 = uint32(*val)
+					o0 = uint32(val)
-					o1 = uint32(*val >> 32)
+					o1 = uint32(val >> 32)
 				}
 				// Mach-O wants the addend to be encoded in the instruction
 				// Note that although Mach-O supports ARM64_RELOC_ADDEND, it
@@ -311,30 +311,28 @@ func archreloc(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val *int64) bool {
 
 				// when laid out, the instruction order must always be o1, o2.
 				if ctxt.Arch.ByteOrder == binary.BigEndian {
-					*val = int64(o0)<<32 | int64(o1)
+					val = int64(o0)<<32 | int64(o1)
 				} else {
-					*val = int64(o1)<<32 | int64(o0)
+					val = int64(o1)<<32 | int64(o0)
 				}
 			}
 
-			return true
+			return val, true
 		case objabi.R_CALLARM64,
 			objabi.R_ARM64_TLS_LE,
 			objabi.R_ARM64_TLS_IE:
 			r.Done = false
 			r.Xsym = r.Sym
 			r.Xadd = r.Add
-			return true
+			return val, true
 		}
 	}
 
 	switch r.Type {
 	case objabi.R_CONST:
-		*val = r.Add
+		return r.Add, true
-		return true
 	case objabi.R_GOTOFF:
-		*val = ld.Symaddr(r.Sym) + r.Add - ld.Symaddr(ctxt.Syms.Lookup(".got", 0))
+		return ld.Symaddr(r.Sym) + r.Add - ld.Symaddr(ctxt.Syms.Lookup(".got", 0)), true
-		return true
 	case objabi.R_ADDRARM64:
 		t := ld.Symaddr(r.Sym) + r.Add - ((s.Value + int64(r.Off)) &^ 0xfff)
 		if t >= 1<<32 || t < -1<<32 {
@@ -344,11 +342,11 @@ func archreloc(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val *int64) bool {
 		var o0, o1 uint32
 
 		if ctxt.Arch.ByteOrder == binary.BigEndian {
-			o0 = uint32(*val >> 32)
+			o0 = uint32(val >> 32)
-			o1 = uint32(*val)
+			o1 = uint32(val)
 		} else {
-			o0 = uint32(*val)
+			o0 = uint32(val)
-			o1 = uint32(*val >> 32)
+			o1 = uint32(val >> 32)
 		}
 
 		o0 |= (uint32((t>>12)&3) << 29) | (uint32((t>>12>>2)&0x7ffff) << 5)
@@ -356,11 +354,9 @@ func archreloc(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val *int64) bool {
 
 		// when laid out, the instruction order must always be o1, o2.
 		if ctxt.Arch.ByteOrder == binary.BigEndian {
-			*val = int64(o0)<<32 | int64(o1)
+			return int64(o0)<<32 | int64(o1), true
-		} else {
-			*val = int64(o1)<<32 | int64(o0)
 		}
-		return true
+		return int64(o1)<<32 | int64(o0), true
 	case objabi.R_ARM64_TLS_LE:
 		r.Done = false
 		if ctxt.HeadType != objabi.Hlinux {
@@ -372,18 +368,16 @@ func archreloc(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val *int64) bool {
 		if v < 0 || v >= 32678 {
 			ld.Errorf(s, "TLS offset out of range %d", v)
 		}
-		*val |= v << 5
+		return val | (v << 5), true
-		return true
 	case objabi.R_CALLARM64:
 		t := (ld.Symaddr(r.Sym) + r.Add) - (s.Value + int64(r.Off))
 		if t >= 1<<27 || t < -1<<27 {
 			ld.Errorf(s, "program too large, call relocation distance = %d", t)
 		}
-		*val |= (t >> 2) & 0x03ffffff
+		return val | ((t >> 2) & 0x03ffffff), true
-		return true
 	}
 
-	return false
+	return val, false
 }
 
 func archrelocvariant(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, t int64) int64 {

src/cmd/link/internal/ld/data.go

@@ -198,7 +198,9 @@ func relocsym(ctxt *Link, s *sym.Symbol) {
 			case 8:
 				o = int64(ctxt.Arch.ByteOrder.Uint64(s.P[off:]))
 			}
-			if !thearch.Archreloc(ctxt, r, s, &o) {
+			if offset, ok := thearch.Archreloc(ctxt, r, s, o); ok {
+				o = offset
+			} else {
 				Errorf(s, "unknown reloc to %v: %d (%s)", r.Sym.Name, r.Type, sym.RelocName(ctxt.Arch, r.Type))
 			}
 		case objabi.R_TLS_LE:

src/cmd/link/internal/ld/lib.go

@@ -104,7 +104,7 @@ type Arch struct {
 	Solarisdynld     string
 	Adddynrel        func(*Link, *sym.Symbol, *sym.Reloc) bool
 	Archinit         func(*Link)
-	Archreloc        func(*Link, *sym.Reloc, *sym.Symbol, *int64) bool
+	Archreloc        func(*Link, *sym.Reloc, *sym.Symbol, int64) (int64, bool)
 	Archrelocvariant func(*Link, *sym.Reloc, *sym.Symbol, int64) int64
 	Trampoline       func(*Link, *sym.Reloc, *sym.Symbol)
 	Asmb             func(*Link)

src/cmd/link/internal/mips/asm.go

@@ -82,23 +82,25 @@ func machoreloc1(arch *sys.Arch, out *ld.OutBuf, s *sym.Symbol, r *sym.Reloc, se
 	return false
 }
 
-func applyrel(arch *sys.Arch, r *sym.Reloc, s *sym.Symbol, val *int64, t int64) {
+func applyrel(arch *sys.Arch, r *sym.Reloc, s *sym.Symbol, val int64, t int64) int64 {
 	o := arch.ByteOrder.Uint32(s.P[r.Off:])
 	switch r.Type {
 	case objabi.R_ADDRMIPS, objabi.R_ADDRMIPSTLS:
-		*val = int64(o&0xffff0000 | uint32(t)&0xffff)
+		return int64(o&0xffff0000 | uint32(t)&0xffff)
 	case objabi.R_ADDRMIPSU:
-		*val = int64(o&0xffff0000 | uint32((t+(1<<15))>>16)&0xffff)
+		return int64(o&0xffff0000 | uint32((t+(1<<15))>>16)&0xffff)
 	case objabi.R_CALLMIPS, objabi.R_JMPMIPS:
-		*val = int64(o&0xfc000000 | uint32(t>>2)&^0xfc000000)
+		return int64(o&0xfc000000 | uint32(t>>2)&^0xfc000000)
+	default:
+		return val
 	}
 }
 
-func archreloc(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val *int64) bool {
+func archreloc(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val int64) (int64, bool) {
 	if ctxt.LinkMode == ld.LinkExternal {
 		switch r.Type {
 		default:
-			return false
+			return val, false
 		case objabi.R_ADDRMIPS, objabi.R_ADDRMIPSU:
 			r.Done = false
 
@@ -114,28 +116,23 @@ func archreloc(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val *int64) bool {
 				ld.Errorf(s, "missing section for %s", rs.Name)
 			}
 			r.Xsym = rs
-			applyrel(ctxt.Arch, r, s, val, r.Xadd)
+			return applyrel(ctxt.Arch, r, s, val, r.Xadd), true
-			return true
 		case objabi.R_ADDRMIPSTLS, objabi.R_CALLMIPS, objabi.R_JMPMIPS:
 			r.Done = false
 			r.Xsym = r.Sym
 			r.Xadd = r.Add
-			applyrel(ctxt.Arch, r, s, val, r.Add)
+			return applyrel(ctxt.Arch, r, s, val, r.Add), true
-			return true
 		}
 	}
 
 	switch r.Type {
 	case objabi.R_CONST:
-		*val = r.Add
+		return r.Add, true
-		return true
 	case objabi.R_GOTOFF:
-		*val = ld.Symaddr(r.Sym) + r.Add - ld.Symaddr(ctxt.Syms.Lookup(".got", 0))
+		return ld.Symaddr(r.Sym) + r.Add - ld.Symaddr(ctxt.Syms.Lookup(".got", 0)), true
-		return true
 	case objabi.R_ADDRMIPS, objabi.R_ADDRMIPSU:
 		t := ld.Symaddr(r.Sym) + r.Add
-		applyrel(ctxt.Arch, r, s, val, t)
+		return applyrel(ctxt.Arch, r, s, val, t), true
-		return true
 	case objabi.R_CALLMIPS, objabi.R_JMPMIPS:
 		t := ld.Symaddr(r.Sym) + r.Add
 
@@ -148,19 +145,17 @@ func archreloc(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val *int64) bool {
 			ld.Errorf(s, "direct call too far: %s %x", r.Sym.Name, t)
 		}
 
-		applyrel(ctxt.Arch, r, s, val, t)
+		return applyrel(ctxt.Arch, r, s, val, t), true
-		return true
 	case objabi.R_ADDRMIPSTLS:
 		// thread pointer is at 0x7000 offset from the start of TLS data area
 		t := ld.Symaddr(r.Sym) + r.Add - 0x7000
 		if t < -32768 || t >= 32678 {
 			ld.Errorf(s, "TLS offset out of range %d", t)
 		}
-		applyrel(ctxt.Arch, r, s, val, t)
+		return applyrel(ctxt.Arch, r, s, val, t), true
-		return true
 	}
 
-	return false
+	return val, false
 }
 
 func archrelocvariant(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, t int64) int64 {

src/cmd/link/internal/mips64/asm.go

@@ -99,11 +99,11 @@ func machoreloc1(arch *sys.Arch, out *ld.OutBuf, s *sym.Symbol, r *sym.Reloc, se
 	return false
 }
 
-func archreloc(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val *int64) bool {
+func archreloc(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val int64) (int64, bool) {
 	if ctxt.LinkMode == ld.LinkExternal {
 		switch r.Type {
 		default:
-			return false
+			return val, false
 		case objabi.R_ADDRMIPS,
 			objabi.R_ADDRMIPSU:
 			r.Done = false
@@ -121,34 +121,30 @@ func archreloc(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val *int64) bool {
 			}
 			r.Xsym = rs
 
-			return true
+			return val, true
 		case objabi.R_ADDRMIPSTLS,
 			objabi.R_CALLMIPS,
 			objabi.R_JMPMIPS:
 			r.Done = false
 			r.Xsym = r.Sym
 			r.Xadd = r.Add
-			return true
+			return val, true
 		}
 	}
 
 	switch r.Type {
 	case objabi.R_CONST:
-		*val = r.Add
+		return r.Add, true
-		return true
 	case objabi.R_GOTOFF:
-		*val = ld.Symaddr(r.Sym) + r.Add - ld.Symaddr(ctxt.Syms.Lookup(".got", 0))
+		return ld.Symaddr(r.Sym) + r.Add - ld.Symaddr(ctxt.Syms.Lookup(".got", 0)), true
-		return true
 	case objabi.R_ADDRMIPS,
 		objabi.R_ADDRMIPSU:
 		t := ld.Symaddr(r.Sym) + r.Add
 		o1 := ctxt.Arch.ByteOrder.Uint32(s.P[r.Off:])
 		if r.Type == objabi.R_ADDRMIPS {
-			*val = int64(o1&0xffff0000 | uint32(t)&0xffff)
+			return int64(o1&0xffff0000 | uint32(t)&0xffff), true
-		} else {
-			*val = int64(o1&0xffff0000 | uint32((t+1<<15)>>16)&0xffff)
 		}
-		return true
+		return int64(o1&0xffff0000 | uint32((t+1<<15)>>16)&0xffff), true
 	case objabi.R_ADDRMIPSTLS:
 		// thread pointer is at 0x7000 offset from the start of TLS data area
 		t := ld.Symaddr(r.Sym) + r.Add - 0x7000
@@ -156,18 +152,16 @@ func archreloc(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val *int64) bool {
 			ld.Errorf(s, "TLS offset out of range %d", t)
 		}
 		o1 := ctxt.Arch.ByteOrder.Uint32(s.P[r.Off:])
-		*val = int64(o1&0xffff0000 | uint32(t)&0xffff)
+		return int64(o1&0xffff0000 | uint32(t)&0xffff), true
-		return true
 	case objabi.R_CALLMIPS,
 		objabi.R_JMPMIPS:
 		// Low 26 bits = (S + A) >> 2
 		t := ld.Symaddr(r.Sym) + r.Add
 		o1 := ctxt.Arch.ByteOrder.Uint32(s.P[r.Off:])
-		*val = int64(o1&0xfc000000 | uint32(t>>2)&^0xfc000000)
+		return int64(o1&0xfc000000 | uint32(t>>2)&^0xfc000000), true
-		return true
 	}
 
-	return false
+	return val, false
 }
 
 func archrelocvariant(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, t int64) int64 {

src/cmd/link/internal/ppc64/asm.go

@@ -474,14 +474,14 @@ func symtoc(ctxt *ld.Link, s *sym.Symbol) int64 {
 	return toc.Value
 }
 
-func archrelocaddr(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val *int64) bool {
+func archrelocaddr(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val int64) int64 {
 	var o1, o2 uint32
 	if ctxt.Arch.ByteOrder == binary.BigEndian {
-		o1 = uint32(*val >> 32)
+		o1 = uint32(val >> 32)
-		o2 = uint32(*val)
+		o2 = uint32(val)
 	} else {
-		o1 = uint32(*val)
+		o1 = uint32(val)
-		o2 = uint32(*val >> 32)
+		o2 = uint32(val >> 32)
 	}
 
 	// We are spreading a 31-bit address across two instructions, putting the
@@ -510,15 +510,13 @@ func archrelocaddr(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val *int64) bool
 		}
 		o2 |= uint32(t) & 0xfffc
 	default:
-		return false
+		return -1
 	}
 
 	if ctxt.Arch.ByteOrder == binary.BigEndian {
-		*val = int64(o1)<<32 | int64(o2)
+		return int64(o1)<<32 | int64(o2)
-	} else {
-		*val = int64(o2)<<32 | int64(o1)
 	}
-	return true
+	return int64(o2)<<32 | int64(o1)
 }
 
 // resolve direct jump relocation r in s, and add trampoline if necessary
@@ -623,17 +621,17 @@ func gentramp(arch *sys.Arch, linkmode ld.LinkMode, tramp, target *sym.Symbol, o
 	arch.ByteOrder.PutUint32(tramp.P[12:], o4)
 }
 
-func archreloc(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val *int64) bool {
+func archreloc(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val int64) (int64, bool) {
 	if ctxt.LinkMode == ld.LinkExternal {
 		switch r.Type {
 		default:
-			return false
+			return val, false
 		case objabi.R_POWER_TLS, objabi.R_POWER_TLS_LE, objabi.R_POWER_TLS_IE:
 			r.Done = false
 			// check Outer is nil, Type is TLSBSS?
 			r.Xadd = r.Add
 			r.Xsym = r.Sym
-			return true
+			return val, true
 		case objabi.R_ADDRPOWER,
 			objabi.R_ADDRPOWER_DS,
 			objabi.R_ADDRPOWER_TOCREL,
@@ -655,24 +653,22 @@ func archreloc(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val *int64) bool {
 			}
 			r.Xsym = rs
 
-			return true
+			return val, true
 		case objabi.R_CALLPOWER:
 			r.Done = false
 			r.Xsym = r.Sym
 			r.Xadd = r.Add
-			return true
+			return val, true
 		}
 	}
 
 	switch r.Type {
 	case objabi.R_CONST:
-		*val = r.Add
+		return r.Add, true
-		return true
 	case objabi.R_GOTOFF:
-		*val = ld.Symaddr(r.Sym) + r.Add - ld.Symaddr(ctxt.Syms.Lookup(".got", 0))
+		return ld.Symaddr(r.Sym) + r.Add - ld.Symaddr(ctxt.Syms.Lookup(".got", 0)), true
-		return true
 	case objabi.R_ADDRPOWER, objabi.R_ADDRPOWER_DS:
-		return archrelocaddr(ctxt, r, s, val)
+		return archrelocaddr(ctxt, r, s, val), true
 	case objabi.R_CALLPOWER:
 		// Bits 6 through 29 = (S + A - P) >> 2
 
@@ -686,12 +682,10 @@ func archreloc(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val *int64) bool {
 		if int64(int32(t<<6)>>6) != t {
 			ld.Errorf(s, "direct call too far: %s %x", r.Sym.Name, t)
 		}
-		*val |= int64(uint32(t) &^ 0xfc000003)
+		return val | int64(uint32(t)&^0xfc000003), true
-		return true
 	case objabi.R_POWER_TOC: // S + A - .TOC.
-		*val = ld.Symaddr(r.Sym) + r.Add - symtoc(ctxt, s)
+		return ld.Symaddr(r.Sym) + r.Add - symtoc(ctxt, s), true
 
-		return true
 	case objabi.R_POWER_TLS_LE:
 		// The thread pointer points 0x7000 bytes after the start of the
 		// thread local storage area as documented in section "3.7.2 TLS
@@ -701,11 +695,10 @@ func archreloc(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val *int64) bool {
 		if int64(int16(v)) != v {
 			ld.Errorf(s, "TLS offset out of range %d", v)
 		}
-		*val = (*val &^ 0xffff) | (v & 0xffff)
+		return (val &^ 0xffff) | (v & 0xffff), true
-		return true
 	}
 
-	return false
+	return val, false
 }
 
 func archrelocvariant(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, t int64) int64 {

src/cmd/link/internal/s390x/asm.go

@@ -384,21 +384,19 @@ func machoreloc1(arch *sys.Arch, out *ld.OutBuf, s *sym.Symbol, r *sym.Reloc, se
 	return false
 }
 
-func archreloc(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val *int64) bool {
+func archreloc(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val int64) (int64, bool) {
 	if ctxt.LinkMode == ld.LinkExternal {
-		return false
+		return val, false
 	}
 
 	switch r.Type {
 	case objabi.R_CONST:
-		*val = r.Add
+		return r.Add, true
-		return true
 	case objabi.R_GOTOFF:
-		*val = ld.Symaddr(r.Sym) + r.Add - ld.Symaddr(ctxt.Syms.Lookup(".got", 0))
+		return ld.Symaddr(r.Sym) + r.Add - ld.Symaddr(ctxt.Syms.Lookup(".got", 0)), true
-		return true
 	}
 
-	return false
+	return val, false
 }
 
 func archrelocvariant(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, t int64) int64 {

src/cmd/link/internal/x86/asm.go

@@ -491,20 +491,18 @@ func pereloc1(arch *sys.Arch, out *ld.OutBuf, s *sym.Symbol, r *sym.Reloc, secto
 	return true
 }
 
-func archreloc(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val *int64) bool {
+func archreloc(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val int64) (int64, bool) {
 	if ctxt.LinkMode == ld.LinkExternal {
-		return false
+		return val, false
 	}
 	switch r.Type {
 	case objabi.R_CONST:
-		*val = r.Add
+		return r.Add, true
-		return true
 	case objabi.R_GOTOFF:
-		*val = ld.Symaddr(r.Sym) + r.Add - ld.Symaddr(ctxt.Syms.Lookup(".got", 0))
+		return ld.Symaddr(r.Sym) + r.Add - ld.Symaddr(ctxt.Syms.Lookup(".got", 0)), true
-		return true
 	}
 
-	return false
+	return val, false
 }
 
 func archrelocvariant(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, t int64) int64 {