cmd/internal/gc: increase registerization limits

Also clean up code a little.

Change-Id: I23b7d2b7871b31e0974f1305e54f0c18dcab05d9
Reviewed-on: https://go-review.googlesource.com/7746Reviewed-by: Dave Cheney <dave@cheney.net>
Reviewed-by: Rob Pike <r@golang.org>

src/cmd/6g/peep.go

@@ -326,7 +326,7 @@ func pushback(r0 *gc.Flow) {
 	}
 
 	if b == nil {
-		if gc.Debug['v'] != 0 {
+		if gc.Debug['P'] != 0 && gc.Debug['v'] != 0 {
 			fmt.Printf("no pushback: %v\n", r0.Prog)
 			if r != nil {
 				fmt.Printf("\t%v [%d]\n", r.Prog, gc.Uniqs(r) != nil)
@@ -336,7 +336,7 @@ func pushback(r0 *gc.Flow) {
 		return
 	}
 
-	if gc.Debug['v'] != 0 {
+	if gc.Debug['P'] != 0 && gc.Debug['v'] != 0 {
 		fmt.Printf("pushback\n")
 		for r := (*gc.Flow)(b); ; r = r.Link {
 			fmt.Printf("\t%v\n", r.Prog)
@@ -366,7 +366,7 @@ func pushback(r0 *gc.Flow) {
 	p0.From = t.From
 	p0.To = t.To
 
-	if gc.Debug['v'] != 0 {
+	if gc.Debug['P'] != 0 && gc.Debug['v'] != 0 {
 		fmt.Printf("\tafter\n")
 		for r := (*gc.Flow)(b); ; r = r.Link {
 			fmt.Printf("\t%v\n", r.Prog)

src/cmd/internal/gc/bits.go

-// Inferno utils/cc/bits.c
-// http://code.google.com/p/inferno-os/source/browse/utils/cc/bits.c
-//
-//	Copyright © 1994-1999 Lucent Technologies Inc.  All rights reserved.
-//	Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
-//	Portions Copyright © 1997-1999 Vita Nuova Limited
-//	Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
-//	Portions Copyright © 2004,2006 Bruce Ellis
-//	Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
-//	Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
-//	Portions Copyright © 2009 The Go Authors.  All rights reserved.
-//
-// Permission is hereby granted, free of charge, to any person obtaining a copy
-// of this software and associated documentation files (the "Software"), to deal
-// in the Software without restriction, including without limitation the rights
-// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-// copies of the Software, and to permit persons to whom the Software is
-// furnished to do so, subject to the following conditions:
-//
-// The above copyright notice and this permission notice shall be included in
-// all copies or substantial portions of the Software.
-//
-// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
-// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
-// THE SOFTWARE.
-
-package gc
-
-import "fmt"
-
-/*
-Bits
-bor(Bits a, Bits b)
-{
-	Bits c;
-	int i;
-
-	for(i=0; i<BITS; i++)
-		c.b[i] = a.b[i] | b.b[i];
-	return c;
-}
-
-Bits
-band(Bits a, Bits b)
-{
-	Bits c;
-	int i;
-
-	for(i=0; i<BITS; i++)
-		c.b[i] = a.b[i] & b.b[i];
-	return c;
-}
-
-Bits
-bnot(Bits a)
-{
-	Bits c;
-	int i;
-
-	for(i=0; i<BITS; i++)
-		c.b[i] = ~a.b[i];
-	return c;
-}
-*/
-func bany(a *Bits) bool {
-	for i := 0; i < BITS; i++ {
-		if a.b[i] != 0 {
-			return true
-		}
-	}
-	return false
-}
-
-/*
-int
-beq(Bits a, Bits b)
-{
-	int i;
-
-	for(i=0; i<BITS; i++)
-		if(a.b[i] != b.b[i])
-			return 0;
-	return 1;
-}
-*/
-func bnum(a Bits) int {
-	var b uint64
-
-	for i := 0; i < BITS; i++ {
-		b = a.b[i]
-		if b != 0 {
-			return 64*i + Bitno(b)
-		}
-	}
-
-	Fatal("bad in bnum")
-	return 0
-}
-
-func blsh(n uint) Bits {
-	c := zbits
-	c.b[n/64] = 1 << (n % 64)
-	return c
-}
-
-func btest(a *Bits, n uint) bool {
-	return a.b[n/64]&(1<<(n%64)) != 0
-}
-
-func biset(a *Bits, n uint) {
-	a.b[n/64] |= 1 << (n % 64)
-}
-
-func biclr(a *Bits, n uint) {
-	a.b[n/64] &^= (1 << (n % 64))
-}
-
-func Bitno(b uint64) int {
-	for i := 0; i < 64; i++ {
-		if b&(1<<uint(i)) != 0 {
-			return i
-		}
-	}
-	Fatal("bad in bitno")
-	return 0
-}
-
-func Qconv(bits Bits, flag int) string {
-	var fp string
-
-	var i int
-
-	first := 1
-
-	for bany(&bits) {
-		i = bnum(bits)
-		if first != 0 {
-			first = 0
-		} else {
-			fp += " "
-		}
-		if var_[i].node == nil || var_[i].node.Sym == nil {
-			fp += fmt.Sprintf("$%d", i)
-		} else {
-			fp += fmt.Sprintf("%s(%d)", var_[i].node.Sym.Name, i)
-			if var_[i].offset != 0 {
-				fp += fmt.Sprintf("%+d", int64(var_[i].offset))
-			}
-		}
-
-		biclr(&bits, uint(i))
-	}
-
-	return fp
-}

src/cmd/internal/gc/go.go

@@ -351,30 +351,6 @@ const (
 	Ecomplit  = 1 << 11 // type in composite literal
 )
 
-const (
-	BITS = 3
-	NVAR = BITS * 64
-)
-
-type Bits struct {
-	b [BITS]uint64
-}
-
-var zbits Bits
-
-type Var struct {
-	offset     int64
-	node       *Node
-	nextinnode *Var
-	width      int
-	id         int
-	name       int8
-	etype      int8
-	addr       int8
-}
-
-var var_ [NVAR]Var
-
 type Typedef struct {
 	Name   string
 	Etype  int

src/cmd/internal/gc/popt.go

-// Derived from Inferno utils/6c/reg.c
-// http://code.google.com/p/inferno-os/source/browse/utils/6c/reg.c
+// Derived from Inferno utils/6c/gc.h
+// http://code.google.com/p/inferno-os/source/browse/utils/6c/gc.h
 //
 //	Copyright © 1994-1999 Lucent Technologies Inc.  All rights reserved.
 //	Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
@@ -28,6 +28,8 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 // THE SOFTWARE.
 
+// "Portable" optimizations.
+
 package gc
 
 import (
@@ -37,124 +39,6 @@ import (
 	"strings"
 )
 
-// "Portable" optimizations.
-
-// Derived from Inferno utils/6c/gc.h
-// http://code.google.com/p/inferno-os/source/browse/utils/6c/gc.h
-//
-//	Copyright © 1994-1999 Lucent Technologies Inc.  All rights reserved.
-//	Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
-//	Portions Copyright © 1997-1999 Vita Nuova Limited
-//	Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
-//	Portions Copyright © 2004,2006 Bruce Ellis
-//	Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
-//	Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
-//	Portions Copyright © 2009 The Go Authors.  All rights reserved.
-//
-// Permission is hereby granted, free of charge, to any person obtaining a copy
-// of this software and associated documentation files (the "Software"), to deal
-// in the Software without restriction, including without limitation the rights
-// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-// copies of the Software, and to permit persons to whom the Software is
-// furnished to do so, subject to the following conditions:
-//
-// The above copyright notice and this permission notice shall be included in
-// all copies or substantial portions of the Software.
-//
-// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
-// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
-// THE SOFTWARE.
-
-const (
-	CLOAD = 5
-	CREF  = 5
-	CINF  = 1000
-	LOOP  = 3
-)
-
-type Reg struct {
-	set  Bits // regopt variables written by this instruction.
-	use1 Bits // regopt variables read by prog->from.
-	use2 Bits // regopt variables read by prog->to.
-
-	// refahead/refbehind are the regopt variables whose current
-	// value may be used in the following/preceding instructions
-	// up to a CALL (or the value is clobbered).
-	refbehind Bits
-	refahead  Bits
-
-	// calahead/calbehind are similar, but for variables in
-	// instructions that are reachable after hitting at least one
-	// CALL.
-	calbehind Bits
-	calahead  Bits
-
-	regdiff Bits
-	act     Bits
-	regu    uint64 // register used bitmap
-}
-
-type Rgn struct {
-	enter *Flow
-	cost  int16
-	varno int16
-	regno int16
-}
-
-var Z *Node
-
-// A Reg is a wrapper around a single Prog (one instruction) that holds
-// register optimization information while the optimizer runs.
-// r->prog is the instruction.
-
-var R *Reg
-
-const (
-	NRGN = 600
-)
-
-// A Rgn represents a single regopt variable over a region of code
-// where a register could potentially be dedicated to that variable.
-// The code encompassed by a Rgn is defined by the flow graph,
-// starting at enter, flood-filling forward while varno is refahead
-// and backward while varno is refbehind, and following branches.  A
-// single variable may be represented by multiple disjoint Rgns and
-// each Rgn may choose a different register for that variable.
-// Registers are allocated to regions greedily in order of descending
-// cost.
-
-var zreg Reg
-
-var region [NRGN]Rgn
-
-var rgp *Rgn
-
-var nregion int
-
-var nvar int
-
-var regbits uint64
-
-var externs Bits
-
-var params Bits
-
-var consts Bits
-
-var addrs Bits
-
-var ivar Bits
-
-var ovar Bits
-
-var change int
-
-var maxnr int32
-
 type OptStats struct {
 	Ncvtreg int32
 	Nspill  int32
@@ -354,6 +238,11 @@ func fixjmp(firstp *obj.Prog) {
 
 var flowmark int
 
+// MaxFlowProg is the maximum size program (counted in instructions)
+// for which the flow code will build a graph. Functions larger than this limit
+// will not have flow graphs and consequently will not be optimized.
+const MaxFlowProg = 50000
+
 func Flowstart(firstp *obj.Prog, newData func() interface{}) *Graph {
 	// Count and mark instructions to annotate.
 	nf := 0
@@ -372,8 +261,10 @@ func Flowstart(firstp *obj.Prog, newData func() interface{}) *Graph {
 		return nil
 	}
 
-	if nf >= 20000 {
-		// fatal("%S is too big (%d instructions)", curfn->nname->sym, nf);
+	if nf >= MaxFlowProg {
+		if Debug['v'] != 0 {
+			Warn("%v is too big (%d instructions)", Sconv(Curfn.Nname.Sym, 0), nf)
+		}
 		return nil
 	}
 
@@ -678,7 +569,7 @@ func canmerge(n *Node) bool {
 
 func mergetemp(firstp *obj.Prog) {
 	const (
-		debugmerge = 1
+		debugmerge = 0
 	)
 
 	g := Flowstart(firstp, nil)