Revert "cmd/internal/obj/arm64, cmd/link: use two instructions rather than three for loads from memory"

This reverts commit 3a9bc571b0.

Breaks darwin/arm64.

Change-Id: Ib958beacabca48020a6a47332fbdec99d994060b
Reviewed-on: https://go-review.googlesource.com/16906
Reviewed-by: Michael Hudson-Doyle <michael.hudson@canonical.com>

src/cmd/internal/obj/arm64/asm7.go

@@ -260,16 +260,16 @@ var optab = []Optab{
 	{AMOVW, C_VCONADDR, C_NONE, C_REG, 68, 8, 0, 0, 0},
 	{AMOVD, C_VCON, C_NONE, C_REG, 12, 4, 0, LFROM, 0},
 	{AMOVD, C_VCONADDR, C_NONE, C_REG, 68, 8, 0, 0, 0},
-	{AMOVB, C_REG, C_NONE, C_ADDR, 64, 8, 0, 0, 0},
+	{AMOVB, C_REG, C_NONE, C_ADDR, 64, 12, 0, 0, 0},
-	{AMOVBU, C_REG, C_NONE, C_ADDR, 64, 8, 0, 0, 0},
+	{AMOVBU, C_REG, C_NONE, C_ADDR, 64, 12, 0, 0, 0},
-	{AMOVH, C_REG, C_NONE, C_ADDR, 64, 8, 0, 0, 0},
+	{AMOVH, C_REG, C_NONE, C_ADDR, 64, 12, 0, 0, 0},
-	{AMOVW, C_REG, C_NONE, C_ADDR, 64, 8, 0, 0, 0},
+	{AMOVW, C_REG, C_NONE, C_ADDR, 64, 12, 0, 0, 0},
-	{AMOVD, C_REG, C_NONE, C_ADDR, 64, 8, 0, 0, 0},
+	{AMOVD, C_REG, C_NONE, C_ADDR, 64, 12, 0, 0, 0},
-	{AMOVB, C_ADDR, C_NONE, C_REG, 65, 8, 0, 0, 0},
+	{AMOVB, C_ADDR, C_NONE, C_REG, 65, 12, 0, 0, 0},
-	{AMOVBU, C_ADDR, C_NONE, C_REG, 65, 8, 0, 0, 0},
+	{AMOVBU, C_ADDR, C_NONE, C_REG, 65, 12, 0, 0, 0},
-	{AMOVH, C_ADDR, C_NONE, C_REG, 65, 8, 0, 0, 0},
+	{AMOVH, C_ADDR, C_NONE, C_REG, 65, 12, 0, 0, 0},
-	{AMOVW, C_ADDR, C_NONE, C_REG, 65, 8, 0, 0, 0},
+	{AMOVW, C_ADDR, C_NONE, C_REG, 65, 12, 0, 0, 0},
-	{AMOVD, C_ADDR, C_NONE, C_REG, 65, 8, 0, 0, 0},
+	{AMOVD, C_ADDR, C_NONE, C_REG, 65, 12, 0, 0, 0},
 	{AMOVD, C_TLS_LE, C_NONE, C_REG, 69, 4, 0, 0, 0},
 	{AMOVD, C_TLS_IE, C_NONE, C_REG, 70, 8, 0, 0, 0},
 	{AMUL, C_REG, C_REG, C_REG, 15, 4, 0, 0, 0},
@@ -450,10 +450,10 @@ var optab = []Optab{
 	{AFMOVS, C_LOREG, C_NONE, C_FREG, 31, 8, 0, LFROM, 0},
 	{AFMOVD, C_LAUTO, C_NONE, C_FREG, 31, 8, REGSP, LFROM, 0},
 	{AFMOVD, C_LOREG, C_NONE, C_FREG, 31, 8, 0, LFROM, 0},
-	{AFMOVS, C_FREG, C_NONE, C_ADDR, 64, 8, 0, 0, 0},
+	{AFMOVS, C_FREG, C_NONE, C_ADDR, 64, 12, 0, 0, 0},
-	{AFMOVS, C_ADDR, C_NONE, C_FREG, 65, 8, 0, 0, 0},
+	{AFMOVS, C_ADDR, C_NONE, C_FREG, 65, 12, 0, 0, 0},
-	{AFMOVD, C_FREG, C_NONE, C_ADDR, 64, 8, 0, 0, 0},
+	{AFMOVD, C_FREG, C_NONE, C_ADDR, 64, 12, 0, 0, 0},
-	{AFMOVD, C_ADDR, C_NONE, C_FREG, 65, 8, 0, 0, 0},
+	{AFMOVD, C_ADDR, C_NONE, C_FREG, 65, 12, 0, 0, 0},
 	{AFADDS, C_FREG, C_NONE, C_FREG, 54, 4, 0, 0, 0},
 	{AFADDS, C_FREG, C_FREG, C_FREG, 54, 4, 0, 0, 0},
 	{AFADDS, C_FCON, C_NONE, C_FREG, 54, 4, 0, 0, 0},
@@ -2701,26 +2701,28 @@ func asmout(ctxt *obj.Link, p *obj.Prog, o *Optab, out []uint32) {
 
 		o1 = ADR(0, uint32(d), uint32(p.To.Reg))
 
-	/* reloc ops */
+		/* reloc ops */
 	case 64: /* movT R,addr -> adrp + add + movT R, (REGTMP) */
 		o1 = ADR(1, 0, REGTMP)
-		o2 = olsr12u(ctxt, int32(opstr12(ctxt, int(p.As))), 0, REGTMP, int(p.From.Reg))
+		o2 = opirr(ctxt, AADD) | REGTMP&31<<5 | REGTMP&31
 		rel := obj.Addrel(ctxt.Cursym)
 		rel.Off = int32(ctxt.Pc)
 		rel.Siz = 8
 		rel.Sym = p.To.Sym
 		rel.Add = p.To.Offset
-		rel.Type = movereloc(p.As)
+		rel.Type = obj.R_ADDRARM64
+		o3 = olsr12u(ctxt, int32(opstr12(ctxt, int(p.As))), 0, REGTMP, int(p.From.Reg))
 
-	case 65: /* movT addr,R -> adrp REGTMP, 0; ldr R, [REGTMP, #0] + relocs */
+	case 65: /* movT addr,R -> adrp + add + movT (REGTMP), R */
 		o1 = ADR(1, 0, REGTMP)
-		o2 = olsr12u(ctxt, int32(opldr12(ctxt, int(p.As))), 0, REGTMP, int(p.To.Reg))
+		o2 = opirr(ctxt, AADD) | REGTMP&31<<5 | REGTMP&31
 		rel := obj.Addrel(ctxt.Cursym)
 		rel.Off = int32(ctxt.Pc)
+		rel.Siz = 8
 		rel.Sym = p.From.Sym
 		rel.Add = p.From.Offset
-		rel.Siz = 8
+		rel.Type = obj.R_ADDRARM64
-		rel.Type = movereloc(p.As)
+		o3 = olsr12u(ctxt, int32(opldr12(ctxt, int(p.As))), 0, REGTMP, int(p.To.Reg))
 
 	case 66: /* ldp O(R)!, (r1, r2); ldp (R)O!, (r1, r2) */
 		v := int32(p.From.Offset)
@@ -4159,19 +4161,3 @@ func movesize(a int) int {
 		return -1
 	}
 }
-
-func movereloc(a int16) int32 {
-	switch movesize(int(a)) {
-	case 0:
-		return obj.R_ARM64_LOAD8
-	case 1:
-		return obj.R_ARM64_LOAD16
-	case 2:
-		return obj.R_ARM64_LOAD32
-	case 3:
-		return obj.R_ARM64_LOAD64
-	case -1:
-		panic("xxx")
-	}
-	return -1
-}

src/cmd/internal/obj/link.go

@@ -467,11 +467,6 @@ const (
 	// referenced (thread local) symbol from the GOT.
 	R_ARM64_TLS_IE
 
-	R_ARM64_LOAD8
-	R_ARM64_LOAD16
-	R_ARM64_LOAD32
-	R_ARM64_LOAD64
-
 	// PPC64.
 
 	// R_POWER_TLS_LE is used to implement the "local exec" model for tls

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

@@ -133,30 +133,6 @@ func elfreloc1(r *ld.Reloc, sectoff int64) int {
 		ld.Thearch.Vput(uint64(sectoff + 4))
 		ld.Thearch.Vput(ld.R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC | uint64(elfsym)<<32)
 
-	case obj.R_ARM64_LOAD8:
-		ld.Thearch.Vput(ld.R_AARCH64_ADR_PREL_PG_HI21 | uint64(elfsym)<<32)
-		ld.Thearch.Vput(uint64(r.Xadd))
-		ld.Thearch.Vput(uint64(sectoff + 4))
-		ld.Thearch.Vput(ld.R_AARCH64_LDST8_ABS_LO12_NC | uint64(elfsym)<<32)
-
-	case obj.R_ARM64_LOAD16:
-		ld.Thearch.Vput(ld.R_AARCH64_ADR_PREL_PG_HI21 | uint64(elfsym)<<32)
-		ld.Thearch.Vput(uint64(r.Xadd))
-		ld.Thearch.Vput(uint64(sectoff + 4))
-		ld.Thearch.Vput(ld.R_AARCH64_LDST16_ABS_LO12_NC | uint64(elfsym)<<32)
-
-	case obj.R_ARM64_LOAD32:
-		ld.Thearch.Vput(ld.R_AARCH64_ADR_PREL_PG_HI21 | uint64(elfsym)<<32)
-		ld.Thearch.Vput(uint64(r.Xadd))
-		ld.Thearch.Vput(uint64(sectoff + 4))
-		ld.Thearch.Vput(ld.R_AARCH64_LDST32_ABS_LO12_NC | uint64(elfsym)<<32)
-
-	case obj.R_ARM64_LOAD64:
-		ld.Thearch.Vput(ld.R_AARCH64_ADR_PREL_PG_HI21 | uint64(elfsym)<<32)
-		ld.Thearch.Vput(uint64(r.Xadd))
-		ld.Thearch.Vput(uint64(sectoff + 4))
-		ld.Thearch.Vput(ld.R_AARCH64_LDST64_ABS_LO12_NC | uint64(elfsym)<<32)
-
 	case obj.R_CALLARM64:
 		if r.Siz != 4 {
 			return -1
@@ -253,72 +229,13 @@ func machoreloc1(r *ld.Reloc, sectoff int64) int {
 	return 0
 }
 
-func archrelocaddr(r *ld.Reloc, s *ld.LSym, val *int64) int {
-	var o1, o2 uint32
-	if ld.Ctxt.Arch.ByteOrder == binary.BigEndian {
-		o1 = uint32(*val >> 32)
-		o2 = uint32(*val)
-	} else {
-		o1 = uint32(*val)
-		o2 = uint32(*val >> 32)
-	}
-
-	// We are inserting an address into two instructions: adrp and
-	// then either addi or a load.
-	address := ld.Symaddr(r.Sym) + r.Add
-	pgaddress := (address &^ 0xfff) - ((s.Value + int64(r.Off)) &^ 0xfff)
-	if pgaddress < -1<<31 || pgaddress >= 1<<31 {
-		ld.Ctxt.Diag("relocation for %s is too big (>=2G): %d", s.Name, pgaddress)
-	}
-	pgoff := uint32(address & 0xfff)
-	o1 |= uint32((((pgaddress >> 12) & 3) << 29) | (((pgaddress >> 12 >> 2) & 0x7ffff) << 5))
-
-	switch r.Type {
-	case obj.R_ADDRARM64, obj.R_ARM64_LOAD8:
-		o2 |= pgoff << 10
-
-	case obj.R_ARM64_LOAD16:
-		if pgoff&0x1 != 0 {
-			ld.Diag("offset for 16-byte load/store has unaligned value %d", pgoff)
-		}
-		o2 |= pgoff << 9
-
-	case obj.R_ARM64_LOAD32:
-		if pgoff&0x3 != 0 {
-			ld.Diag("offset for 32-byte load/store has unaligned value %d", pgoff)
-		}
-		o2 |= pgoff << 8
-
-	case obj.R_ARM64_LOAD64:
-		if pgoff&0x7 != 0 {
-			ld.Diag("offset for 64-byte load/store has unaligned value %d", pgoff)
-		}
-		o2 |= pgoff << 7
-
-	default:
-		return -1
-	}
-
-	if ld.Ctxt.Arch.ByteOrder == binary.BigEndian {
-		*val = int64(o1)<<32 | int64(o2)
-	} else {
-		*val = int64(o2)<<32 | int64(o1)
-	}
-	return 0
-}
-
 func archreloc(r *ld.Reloc, s *ld.LSym, val *int64) int {
 	if ld.Linkmode == ld.LinkExternal {
 		switch r.Type {
 		default:
 			return -1
 
-		case obj.R_ADDRARM64,
+		case obj.R_ADDRARM64:
-			obj.R_ARM64_LOAD8,
-			obj.R_ARM64_LOAD16,
-			obj.R_ARM64_LOAD32,
-			obj.R_ARM64_LOAD64:
-
 			r.Done = 0
 
 			// set up addend for eventual relocation via outer symbol.
@@ -387,8 +304,32 @@ func archreloc(r *ld.Reloc, s *ld.LSym, val *int64) int {
 		*val = ld.Symaddr(r.Sym) + r.Add - ld.Symaddr(ld.Linklookup(ld.Ctxt, ".got", 0))
 		return 0
 
-	case obj.R_ADDRARM64, obj.R_ARM64_LOAD8, obj.R_ARM64_LOAD16, obj.R_ARM64_LOAD32, obj.R_ARM64_LOAD64:
+	case obj.R_ADDRARM64:
-		return archrelocaddr(r, s, val)
+		t := ld.Symaddr(r.Sym) + r.Add - ((s.Value + int64(r.Off)) &^ 0xfff)
+		if t >= 1<<32 || t < -1<<32 {
+			ld.Diag("program too large, address relocation distance = %d", t)
+		}
+
+		var o0, o1 uint32
+
+		if ld.Ctxt.Arch.ByteOrder == binary.BigEndian {
+			o0 = uint32(*val >> 32)
+			o1 = uint32(*val)
+		} else {
+			o0 = uint32(*val)
+			o1 = uint32(*val >> 32)
+		}
+
+		o0 |= (uint32((t>>12)&3) << 29) | (uint32((t>>12>>2)&0x7ffff) << 5)
+		o1 |= uint32(t&0xfff) << 10
+
+		// when laid out, the instruction order must always be o1, o2.
+		if ld.Ctxt.Arch.ByteOrder == binary.BigEndian {
+			*val = int64(o0)<<32 | int64(o1)
+		} else {
+			*val = int64(o1)<<32 | int64(o0)
+		}
+		return 0
 
 	case obj.R_ARM64_TLS_LE:
 		r.Done = 0

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

@@ -372,10 +372,6 @@ const (
 	R_AARCH64_CALL26                      = 283
 	R_AARCH64_ADR_PREL_PG_HI21            = 275
 	R_AARCH64_ADD_ABS_LO12_NC             = 277
-	R_AARCH64_LDST8_ABS_LO12_NC           = 278
-	R_AARCH64_LDST16_ABS_LO12_NC          = 284
-	R_AARCH64_LDST32_ABS_LO12_NC          = 285
-	R_AARCH64_LDST64_ABS_LO12_NC          = 286
 	R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21   = 541
 	R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC = 542
 	R_AARCH64_TLSLE_MOVW_TPREL_G0         = 547