cmd/compile: teach assemblers to accept a Prog allocator

The existing bulk Prog allocator is not concurrency-safe.
To allow for concurrency-safe bulk allocation of Progs,
I want to move Prog allocation and caching upstream,
to the clients of cmd/internal/obj.

This is a preliminary enabling refactoring.
After this CL, instead of calling Ctxt.NewProg
throughout the assemblers, we thread through
a newprog function that returns a new Prog.

That function is set up to be Ctxt.NewProg,
so there are no real changes in this CL;
this CL only establishes the plumbing.

Passes toolstash-check -all.
Negligible compiler performance impact.

Updates #15756

name        old time/op     new time/op     delta
Template        213ms ± 3%      214ms ± 4%    ~     (p=0.574 n=49+47)
Unicode        90.1ms ± 5%     89.9ms ± 4%    ~     (p=0.417 n=50+49)
GoTypes         585ms ± 4%      584ms ± 3%    ~     (p=0.466 n=49+49)
SSA             6.50s ± 3%      6.52s ± 2%    ~     (p=0.251 n=49+49)
Flate           128ms ± 4%      128ms ± 4%    ~     (p=0.673 n=49+50)
GoParser        152ms ± 3%      152ms ± 3%    ~     (p=0.810 n=48+49)
Reflect         372ms ± 4%      372ms ± 5%    ~     (p=0.778 n=49+50)
Tar             113ms ± 5%      111ms ± 4%  -0.98%  (p=0.016 n=50+49)
XML             208ms ± 3%      208ms ± 2%    ~     (p=0.483 n=47+49)
[Geo mean]      285ms           285ms       -0.17%

name        old user-ns/op  new user-ns/op  delta
Template         253M ± 8%       254M ± 9%    ~     (p=0.899 n=50+50)
Unicode          106M ± 9%       106M ±11%    ~     (p=0.642 n=50+50)
GoTypes          736M ± 4%       740M ± 4%    ~     (p=0.121 n=50+49)
SSA             8.82G ± 3%      8.88G ± 2%  +0.65%  (p=0.006 n=49+48)
Flate            147M ± 4%       147M ± 5%    ~     (p=0.844 n=47+48)
GoParser         179M ± 4%       178M ± 6%    ~     (p=0.785 n=50+50)
Reflect          443M ± 6%       441M ± 5%    ~     (p=0.850 n=48+47)
Tar              126M ± 5%       126M ± 5%    ~     (p=0.734 n=50+50)
XML              244M ± 5%       244M ± 5%    ~     (p=0.594 n=49+50)
[Geo mean]       341M            341M       +0.11%

Change-Id: Ice962f61eb3a524c2db00a166cb582c22caa7d68
Reviewed-on: https://go-review.googlesource.com/39633
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

src/cmd/internal/obj/arm/asm5.go

@@ -279,7 +279,7 @@ var deferreturn *obj.LSym
 // p->pc if extra padding is necessary.
 // In rare cases, asmoutnacl might split p into two instructions.
 // origPC is the PC for this Prog (no padding is taken into account).
-func asmoutnacl(ctxt *obj.Link, origPC int32, p *obj.Prog, o *Optab, out []uint32) int {
+func asmoutnacl(ctxt *obj.Link, newprog obj.ProgAlloc, origPC int32, p *obj.Prog, o *Optab, out []uint32) int {
 	size := int(o.size)
 
 	// instruction specific
@@ -406,7 +406,7 @@ func asmoutnacl(ctxt *obj.Link, origPC int32, p *obj.Prog, o *Optab, out []uint3
 			// split it into two instructions:
 			// 	ADD $-100004, R13
 			// 	MOVW R14, 0(R13)
-			q := ctxt.NewProg()
+			q := newprog()
 
 			p.Scond &^= C_WBIT
 			*q = *p
@@ -486,7 +486,7 @@ func asmoutnacl(ctxt *obj.Link, origPC int32, p *obj.Prog, o *Optab, out []uint3
 				if p.Scond&(C_PBIT|C_WBIT) != 0 {
 					ctxt.Diag("unsupported instruction (.P/.W): %v", p)
 				}
-				q := ctxt.NewProg()
+				q := newprog()
 				*q = *p
 				var a2 *obj.Addr
 				if p.To.Type == obj.TYPE_MEM {
@@ -547,7 +547,7 @@ func asmoutnacl(ctxt *obj.Link, origPC int32, p *obj.Prog, o *Optab, out []uint3
 	return size
 }
 
-func span5(ctxt *obj.Link, cursym *obj.LSym) {
+func span5(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 	var p *obj.Prog
 	var op *obj.Prog
 
@@ -572,7 +572,7 @@ func span5(ctxt *obj.Link, cursym *obj.LSym) {
 	var o *Optab
 	for ; p != nil || ctxt.Blitrl != nil; op, p = p, p.Link {
 		if p == nil {
-			if checkpool(ctxt, op, 0) {
+			if checkpool(ctxt, newprog, op, 0) {
 				p = op
 				continue
 			}
@@ -588,7 +588,7 @@ func span5(ctxt *obj.Link, cursym *obj.LSym) {
 		if ctxt.Headtype != obj.Hnacl {
 			m = int(o.size)
 		} else {
-			m = asmoutnacl(ctxt, c, p, o, nil)
+			m = asmoutnacl(ctxt, newprog, c, p, o, nil)
 			c = int32(p.Pc)     // asmoutnacl might change pc for alignment
 			o = oplook(ctxt, p) // asmoutnacl might change p in rare cases
 		}
@@ -600,7 +600,7 @@ func span5(ctxt *obj.Link, cursym *obj.LSym) {
 		// must check literal pool here in case p generates many instructions
 		if ctxt.Blitrl != nil {
 			i = m
-			if checkpool(ctxt, op, i) {
+			if checkpool(ctxt, newprog, op, i) {
 				p = op
 				continue
 			}
@@ -613,19 +613,19 @@ func span5(ctxt *obj.Link, cursym *obj.LSym) {
 
 		switch o.flag & (LFROM | LTO | LPOOL) {
 		case LFROM:
-			addpool(ctxt, p, &p.From)
+			addpool(ctxt, newprog, p, &p.From)
 
 		case LTO:
-			addpool(ctxt, p, &p.To)
+			addpool(ctxt, newprog, p, &p.To)
 
 		case LPOOL:
 			if p.Scond&C_SCOND == C_SCOND_NONE {
-				flushpool(ctxt, p, 0, 0)
+				flushpool(ctxt, newprog, p, 0, 0)
 			}
 		}
 
 		if p.As == AMOVW && p.To.Type == obj.TYPE_REG && p.To.Reg == REGPC && p.Scond&C_SCOND == C_SCOND_NONE {
-			flushpool(ctxt, p, 0, 0)
+			flushpool(ctxt, newprog, p, 0, 0)
 		}
 		c += int32(m)
 	}
@@ -685,7 +685,7 @@ func span5(ctxt *obj.Link, cursym *obj.LSym) {
 			if ctxt.Headtype != obj.Hnacl {
 				m = int(o.size)
 			} else {
-				m = asmoutnacl(ctxt, c, p, o, nil)
+				m = asmoutnacl(ctxt, newprog, c, p, o, nil)
 			}
 			if p.Pc != int64(opc) {
 				bflag = 1
@@ -746,7 +746,7 @@ func span5(ctxt *obj.Link, cursym *obj.LSym) {
 			asmout(ctxt, p, o, out[:])
 			m = int(o.size)
 		} else {
-			m = asmoutnacl(ctxt, c, p, o, out[:])
+			m = asmoutnacl(ctxt, newprog, c, p, o, out[:])
 			if int64(opc) != p.Pc {
 				ctxt.Diag("asmoutnacl broken: pc changed (%d->%d) in last stage: %v", opc, int32(p.Pc), p)
 			}
@@ -795,22 +795,22 @@ func span5(ctxt *obj.Link, cursym *obj.LSym) {
  * drop the pool now, and branch round it.
  * this happens only in extended basic blocks that exceed 4k.
  */
-func checkpool(ctxt *obj.Link, p *obj.Prog, sz int) bool {
+func checkpool(ctxt *obj.Link, newprog obj.ProgAlloc, p *obj.Prog, sz int) bool {
 	if pool.size >= 0xff0 || immaddr(int32((p.Pc+int64(sz)+4)+4+int64(12+pool.size)-int64(pool.start+8))) == 0 {
-		return flushpool(ctxt, p, 1, 0)
+		return flushpool(ctxt, newprog, p, 1, 0)
 	} else if p.Link == nil {
-		return flushpool(ctxt, p, 2, 0)
+		return flushpool(ctxt, newprog, p, 2, 0)
 	}
 	return false
 }
 
-func flushpool(ctxt *obj.Link, p *obj.Prog, skip int, force int) bool {
+func flushpool(ctxt *obj.Link, newprog obj.ProgAlloc, p *obj.Prog, skip int, force int) bool {
 	if ctxt.Blitrl != nil {
 		if skip != 0 {
 			if false && skip == 1 {
 				fmt.Printf("note: flush literal pool at %x: len=%d ref=%x\n", uint64(p.Pc+4), pool.size, pool.start)
 			}
-			q := ctxt.NewProg()
+			q := newprog()
 			q.As = AB
 			q.To.Type = obj.TYPE_BRANCH
 			q.Pcond = p.Link
@@ -822,7 +822,7 @@ func flushpool(ctxt *obj.Link, p *obj.Prog, skip int, force int) bool {
 		}
 		if ctxt.Headtype == obj.Hnacl && pool.size%16 != 0 {
 			// if pool is not multiple of 16 bytes, add an alignment marker
-			q := ctxt.NewProg()
+			q := newprog()
 
 			q.As = ADATABUNDLEEND
 			ctxt.Elitrl.Link = q
@@ -850,7 +850,7 @@ func flushpool(ctxt *obj.Link, p *obj.Prog, skip int, force int) bool {
 	return false
 }
 
-func addpool(ctxt *obj.Link, p *obj.Prog, a *obj.Addr) {
+func addpool(ctxt *obj.Link, newprog obj.ProgAlloc, p *obj.Prog, a *obj.Addr) {
 	var t obj.Prog
 
 	c := aclass(ctxt, a)
@@ -894,7 +894,7 @@ func addpool(ctxt *obj.Link, p *obj.Prog, a *obj.Addr) {
 
 	if ctxt.Headtype == obj.Hnacl && pool.size%16 == 0 {
 		// start a new data bundle
-		q := ctxt.NewProg()
+		q := newprog()
 		q.As = ADATABUNDLE
 		q.Pc = int64(pool.size)
 		pool.size += 4
@@ -908,7 +908,7 @@ func addpool(ctxt *obj.Link, p *obj.Prog, a *obj.Addr) {
 		ctxt.Elitrl = q
 	}
 
-	q := ctxt.NewProg()
+	q := newprog()
 	*q = t
 	q.Pc = int64(pool.size)
 

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

@@ -524,7 +524,7 @@ var pool struct {
 	size  uint32
 }
 
-func span7(ctxt *obj.Link, cursym *obj.LSym) {
+func span7(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 	p := cursym.Text
 	if p == nil || p.Link == nil { // handle external functions and ELF section symbols
 		return
@@ -557,19 +557,19 @@ func span7(ctxt *obj.Link, cursym *obj.LSym) {
 
 		switch o.flag & (LFROM | LTO) {
 		case LFROM:
-			addpool(ctxt, p, &p.From)
+			addpool(ctxt, newprog, p, &p.From)
 
 		case LTO:
-			addpool(ctxt, p, &p.To)
+			addpool(ctxt, newprog, p, &p.To)
 			break
 		}
 
 		if p.As == AB || p.As == obj.ARET || p.As == AERET { /* TODO: other unconditional operations */
-			checkpool(ctxt, p, 0)
+			checkpool(ctxt, newprog, p, 0)
 		}
 		c += int64(m)
 		if ctxt.Blitrl != nil {
-			checkpool(ctxt, p, 1)
+			checkpool(ctxt, newprog, p, 1)
 		}
 	}
 
@@ -598,14 +598,14 @@ func span7(ctxt *obj.Link, cursym *obj.LSym) {
 			if (o.type_ == 7 || o.type_ == 39) && p.Pcond != nil { // 7: BEQ and like, 39: CBZ and like
 				otxt := p.Pcond.Pc - c
 				if otxt <= -(1<<18)+10 || otxt >= (1<<18)-10 {
-					q := ctxt.NewProg()
+					q := newprog()
 					q.Link = p.Link
 					p.Link = q
 					q.As = AB
 					q.To.Type = obj.TYPE_BRANCH
 					q.Pcond = p.Pcond
 					p.Pcond = q
-					q = ctxt.NewProg()
+					q = newprog()
 					q.Link = p.Link
 					p.Link = q
 					q.As = AB
@@ -670,21 +670,21 @@ func span7(ctxt *obj.Link, cursym *obj.LSym) {
  * to go out of range of a 1Mb PC-relative offset
  * drop the pool now, and branch round it.
  */
-func checkpool(ctxt *obj.Link, p *obj.Prog, skip int) {
+func checkpool(ctxt *obj.Link, newprog obj.ProgAlloc, p *obj.Prog, skip int) {
 	if pool.size >= 0xffff0 || !ispcdisp(int32(p.Pc+4+int64(pool.size)-int64(pool.start)+8)) {
-		flushpool(ctxt, p, skip)
+		flushpool(ctxt, newprog, p, skip)
 	} else if p.Link == nil {
-		flushpool(ctxt, p, 2)
+		flushpool(ctxt, newprog, p, 2)
 	}
 }
 
-func flushpool(ctxt *obj.Link, p *obj.Prog, skip int) {
+func flushpool(ctxt *obj.Link, newprog obj.ProgAlloc, p *obj.Prog, skip int) {
 	if ctxt.Blitrl != nil {
 		if skip != 0 {
 			if ctxt.Debugvlog && skip == 1 {
 				fmt.Printf("note: flush literal pool at %#x: len=%d ref=%x\n", uint64(p.Pc+4), pool.size, pool.start)
 			}
-			q := ctxt.NewProg()
+			q := newprog()
 			q.As = AB
 			q.To.Type = obj.TYPE_BRANCH
 			q.Pcond = p.Link
@@ -715,10 +715,10 @@ func flushpool(ctxt *obj.Link, p *obj.Prog, skip int) {
 /*
  * TODO: hash
  */
-func addpool(ctxt *obj.Link, p *obj.Prog, a *obj.Addr) {
+func addpool(ctxt *obj.Link, newprog obj.ProgAlloc, p *obj.Prog, a *obj.Addr) {
 	c := aclass(ctxt, a)
 	lit := ctxt.Instoffset
-	t := *ctxt.NewProg()
+	t := *newprog()
 	t.As = AWORD
 	sz := 4
 
@@ -789,7 +789,7 @@ func addpool(ctxt *obj.Link, p *obj.Prog, a *obj.Addr) {
 		}
 	}
 
-	q := ctxt.NewProg()
+	q := newprog()
 	*q = t
 	q.Pc = int64(pool.size)
 	if ctxt.Blitrl == nil {

src/cmd/internal/obj/ld.go

@@ -76,8 +76,8 @@ func mkfwd(sym *LSym) {
 	}
 }
 
-func Appendp(ctxt *Link, q *Prog) *Prog {
-	p := ctxt.NewProg()
+func Appendp(q *Prog, newprog ProgAlloc) *Prog {
+	p := newprog()
 	p.Link = q.Link
 	q.Link = p
 	p.Pos = q.Pos

src/cmd/internal/obj/link.go

@@ -224,7 +224,8 @@ const (
 // Each Prog is charged to a specific source line in the debug information,
 // specified by Pos.Line().
 // Every Prog has a Ctxt field that defines its context.
-// Progs should be allocated using ctxt.NewProg(), not new(Prog).
+// For performance reasons, Progs usually are usually bulk allocated, cached, and reused;
+// those bulk allocators should always be used, rather than new(Prog).
 //
 // The other fields not yet mentioned are for use by the back ends and should
 // be left zeroed by creators of Prog lists.
@@ -789,9 +790,9 @@ type SymVer struct {
 // LinkArch is the definition of a single architecture.
 type LinkArch struct {
 	*sys.Arch
-	Preprocess func(*Link, *LSym)
-	Assemble   func(*Link, *LSym)
-	Progedit   func(*Link, *Prog)
+	Preprocess func(*Link, *LSym, ProgAlloc)
+	Assemble   func(*Link, *LSym, ProgAlloc)
+	Progedit   func(*Link, *Prog, ProgAlloc)
 	UnaryDst   map[As]bool // Instruction takes one operand, a destination.
 }
 

src/cmd/internal/obj/mips/asm0.go

@@ -373,7 +373,7 @@ var oprange [ALAST & obj.AMask][]Optab
 
 var xcmp [C_NCLASS][C_NCLASS]bool
 
-func span0(ctxt *obj.Link, cursym *obj.LSym) {
+func span0(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 	p := cursym.Text
 	if p == nil || p.Link == nil { // handle external functions and ELF section symbols
 		return
@@ -430,7 +430,7 @@ func span0(ctxt *obj.Link, cursym *obj.LSym) {
 			if o.type_ == 6 && p.Pcond != nil {
 				otxt = p.Pcond.Pc - c
 				if otxt < -(1<<17)+10 || otxt >= (1<<17)-10 {
-					q = ctxt.NewProg()
+					q = newprog()
 					q.Link = p.Link
 					p.Link = q
 					q.As = AJMP
@@ -438,7 +438,7 @@ func span0(ctxt *obj.Link, cursym *obj.LSym) {
 					q.To.Type = obj.TYPE_BRANCH
 					q.Pcond = p.Pcond
 					p.Pcond = q
-					q = ctxt.NewProg()
+					q = newprog()
 					q.Link = p.Link
 					p.Link = q
 					q.As = AJMP
@@ -446,8 +446,8 @@ func span0(ctxt *obj.Link, cursym *obj.LSym) {
 					q.To.Type = obj.TYPE_BRANCH
 					q.Pcond = q.Link.Link
 
-					addnop(ctxt, p.Link)
-					addnop(ctxt, p)
+					addnop(ctxt, p.Link, newprog)
+					addnop(ctxt, p, newprog)
 					bflag = 1
 				}
 			}

src/cmd/internal/obj/pass.go

@@ -117,7 +117,7 @@ func checkaddr(ctxt *Link, p *Prog, a *Addr) {
 	ctxt.Diag("invalid encoding for argument %v", p)
 }
 
-func linkpatch(ctxt *Link, sym *LSym) {
+func linkpatch(ctxt *Link, sym *LSym, newprog ProgAlloc) {
 	var c int32
 	var name string
 	var q *Prog
@@ -130,7 +130,7 @@ func linkpatch(ctxt *Link, sym *LSym) {
 		checkaddr(ctxt, p, &p.To)
 
 		if ctxt.Arch.Progedit != nil {
-			ctxt.Arch.Progedit(ctxt, p)
+			ctxt.Arch.Progedit(ctxt, p, newprog)
 		}
 		if p.To.Type != TYPE_BRANCH {
 			continue

src/cmd/internal/obj/plist.go

@@ -15,6 +15,10 @@ type Plist struct {
 	Curfn   interface{} // holds a *gc.Node, if non-nil
 }
 
+// ProgAlloc is a function that allocates Progs.
+// It is used to provide access to cached/bulk-allocated Progs to the assemblers.
+type ProgAlloc func() *Prog
+
 func Flushplist(ctxt *Link, plist *Plist) {
 	flushplist(ctxt, plist, !ctxt.Debugasm)
 }
@@ -97,6 +101,8 @@ func flushplist(ctxt *Link, plist *Plist, freeProgs bool) {
 		etext = p
 	}
 
+	newprog := ProgAlloc(ctxt.NewProg)
+
 	// Add reference to Go arguments for C or assembly functions without them.
 	for _, s := range text {
 		if !strings.HasPrefix(s.Name, "\"\".") {
@@ -111,7 +117,7 @@ func flushplist(ctxt *Link, plist *Plist, freeProgs bool) {
 		}
 
 		if !found {
-			p := Appendp(ctxt, s.Text)
+			p := Appendp(s.Text, newprog)
 			p.As = AFUNCDATA
 			p.From.Type = TYPE_CONST
 			p.From.Offset = FUNCDATA_ArgsPointerMaps
@@ -124,9 +130,9 @@ func flushplist(ctxt *Link, plist *Plist, freeProgs bool) {
 	// Turn functions into machine code images.
 	for _, s := range text {
 		mkfwd(s)
-		linkpatch(ctxt, s)
-		ctxt.Arch.Preprocess(ctxt, s)
-		ctxt.Arch.Assemble(ctxt, s)
+		linkpatch(ctxt, s, newprog)
+		ctxt.Arch.Preprocess(ctxt, s, newprog)
+		ctxt.Arch.Assemble(ctxt, s, newprog)
 		linkpcln(ctxt, s)
 		makeFuncDebugEntry(ctxt, plist.Curfn, s)
 		if freeProgs {

src/cmd/internal/obj/ppc64/asm9.go

@@ -552,7 +552,7 @@ var oprange [ALAST & obj.AMask][]Optab
 
 var xcmp [C_NCLASS][C_NCLASS]bool
 
-func span9(ctxt *obj.Link, cursym *obj.LSym) {
+func span9(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 	p := cursym.Text
 	if p == nil || p.Link == nil { // handle external functions and ELF section symbols
 		return
@@ -609,14 +609,14 @@ func span9(ctxt *obj.Link, cursym *obj.LSym) {
 			if (o.type_ == 16 || o.type_ == 17) && p.Pcond != nil {
 				otxt = p.Pcond.Pc - c
 				if otxt < -(1<<15)+10 || otxt >= (1<<15)-10 {
-					q = ctxt.NewProg()
+					q = newprog()
 					q.Link = p.Link
 					p.Link = q
 					q.As = ABR
 					q.To.Type = obj.TYPE_BRANCH
 					q.Pcond = p.Pcond
 					p.Pcond = q
-					q = ctxt.NewProg()
+					q = newprog()
 					q.Link = p.Link
 					p.Link = q
 					q.As = ABR

src/cmd/internal/obj/s390x/asmz.go

@@ -385,7 +385,7 @@ var oprange [ALAST & obj.AMask][]Optab
 
 var xcmp [C_NCLASS][C_NCLASS]bool
 
-func spanz(ctxt *obj.Link, cursym *obj.LSym) {
+func spanz(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 	p := cursym.Text
 	if p == nil || p.Link == nil { // handle external functions and ELF section symbols
 		return

src/cmd/internal/obj/x86/asm6.go

@@ -1762,7 +1762,7 @@ func spadjop(ctxt *obj.Link, p *obj.Prog, l, q obj.As) obj.As {
 	return q
 }
 
-func span6(ctxt *obj.Link, s *obj.LSym) {
+func span6(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) {
 	if s.P != nil {
 		return
 	}