cmd/compile: remove amd64 code from package gc and the core gen tool

Parts of the SSA compiler in package gc contain amd64-specific code,
most notably Prog generation. Move this code into package amd64, so that
other architectures can be added more easily.

In package gc, this change is just moving code. There are no functional
changes or even any larger structural changes beyond changing function
names (mostly for export).

In the cmd/compile/internal/ssa/gen tool, more information is included
in arch to remove the AMD64-specific behavior in the main portion of the
tool. The generated opGen.go is identical.

Change-Id: I8eb37c6e6df6de1b65fa7dab6f3bc32c29daf643
Reviewed-on: https://go-review.googlesource.com/20609Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Michael Pratt <mpratt@google.com>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/compile/internal/amd64/galign.go

@@ -110,6 +110,11 @@ func Main() {
 	gc.Thearch.Doregbits = doregbits
 	gc.Thearch.Regnames = regnames
 
+	gc.Thearch.SSARegToReg = ssaRegToReg
+	gc.Thearch.SSAMarkMoves = ssaMarkMoves
+	gc.Thearch.SSAGenValue = ssaGenValue
+	gc.Thearch.SSAGenBlock = ssaGenBlock
+
 	gc.Main()
 	gc.Exit(0)
 }

src/cmd/compile/internal/gc/gen.go

@@ -868,10 +868,10 @@ func gen(n *Node) {
 		Cgen_checknil(n.Left)
 
 	case OVARKILL:
-		gvarkill(n.Left)
+		Gvarkill(n.Left)
 
 	case OVARLIVE:
-		gvarlive(n.Left)
+		Gvarlive(n.Left)
 	}
 
 ret:

src/cmd/compile/internal/gc/go.go

@@ -6,6 +6,7 @@ package gc
 
 import (
 	"bytes"
+	"cmd/compile/internal/ssa"
 	"cmd/internal/obj"
 )
 
@@ -561,6 +562,19 @@ type Arch struct {
 	Doregbits    func(int) uint64
 	Regnames     func(*int) []string
 	Use387       bool // should 8g use 387 FP instructions instead of sse2.
+
+	// SSARegToReg maps ssa register numbers to obj register numbers.
+	SSARegToReg []int16
+
+	// SSAMarkMoves marks any MOVXconst ops that need to avoid clobbering flags.
+	SSAMarkMoves func(*SSAGenState, *ssa.Block)
+
+	// SSAGenValue emits Prog(s) for the Value.
+	SSAGenValue func(*SSAGenState, *ssa.Value)
+
+	// SSAGenBlock emits end-of-block Progs. SSAGenValue should be called
+	// for all values in the block before SSAGenBlock.
+	SSAGenBlock func(s *SSAGenState, b, next *ssa.Block)
 }
 
 var pcloc int32

src/cmd/compile/internal/gc/pgen.go

@@ -108,11 +108,11 @@ func Gvardef(n *Node) {
 	gvardefx(n, obj.AVARDEF)
 }
 
-func gvarkill(n *Node) {
+func Gvarkill(n *Node) {
 	gvardefx(n, obj.AVARKILL)
 }
 
-func gvarlive(n *Node) {
+func Gvarlive(n *Node) {
 	gvardefx(n, obj.AVARLIVE)
 }
 

src/cmd/compile/internal/ssa/gen/AMD64Ops.go

@@ -531,5 +531,12 @@ func init() {
 		{name: "NAN"}, // FP, unordered comparison (parity one)
 	}
 
-	archs = append(archs, arch{"AMD64", AMD64ops, AMD64blocks, regNamesAMD64})
+	archs = append(archs, arch{
+		name:     "AMD64",
+		pkg:      "cmd/internal/obj/x86",
+		genfile:  "../../amd64/ssa.go",
+		ops:      AMD64ops,
+		blocks:   AMD64blocks,
+		regnames: regNamesAMD64,
+	})
 }

src/cmd/compile/internal/ssa/gen/decOps.go

@@ -9,5 +9,9 @@ var decOps = []opData{}
 var decBlocks = []blockData{}
 
 func init() {
-	archs = append(archs, arch{"dec", decOps, decBlocks, nil})
+	archs = append(archs, arch{
+		name:   "dec",
+		ops:    decOps,
+		blocks: decBlocks,
+	})
 }

src/cmd/compile/internal/ssa/gen/genericOps.go

@@ -413,5 +413,9 @@ var genericBlocks = []blockData{
 }
 
 func init() {
-	archs = append(archs, arch{"generic", genericOps, genericBlocks, nil})
+	archs = append(archs, arch{
+		name:   "generic",
+		ops:    genericOps,
+		blocks: genericBlocks,
+	})
 }

src/cmd/compile/internal/ssa/gen/main.go

@@ -14,12 +14,15 @@ import (
 	"go/format"
 	"io/ioutil"
 	"log"
+	"path"
 	"regexp"
 	"sort"
 )
 
 type arch struct {
 	name     string
+	pkg      string // obj package to import for this arch.
+	genfile  string // source file containing opcode code generation.
 	ops      []opData
 	blocks   []blockData
 	regnames []string
@@ -81,7 +84,11 @@ func genOp() {
 
 	fmt.Fprintln(w, "import (")
 	fmt.Fprintln(w, "\"cmd/internal/obj\"")
-	fmt.Fprintln(w, "\"cmd/internal/obj/x86\"")
+	for _, a := range archs {
+		if a.pkg != "" {
+			fmt.Fprintf(w, "%q\n", a.pkg)
+		}
+	}
 	fmt.Fprintln(w, ")")
 
 	// generate Block* declarations
@@ -123,6 +130,8 @@ func genOp() {
 	fmt.Fprintln(w, " { name: \"OpInvalid\" },")
 	for _, a := range archs {
 		fmt.Fprintln(w)
+
+		pkg := path.Base(a.pkg)
 		for _, v := range a.ops {
 			fmt.Fprintln(w, "{")
 			fmt.Fprintf(w, "name:\"%s\",\n", v.name)
@@ -152,7 +161,7 @@ func genOp() {
 				continue
 			}
 			if v.asm != "" {
-				fmt.Fprintf(w, "asm: x86.A%s,\n", v.asm)
+				fmt.Fprintf(w, "asm: %s.A%s,\n", pkg, v.asm)
 			}
 			fmt.Fprintln(w, "reg:regInfo{")
 
@@ -210,24 +219,26 @@ func genOp() {
 		log.Fatalf("can't write output: %v\n", err)
 	}
 
-	// Check that ../gc/ssa.go handles all the arch-specific opcodes.
+	// Check that the arch genfile handles all the arch-specific opcodes.
 	// This is very much a hack, but it is better than nothing.
-	ssa, err := ioutil.ReadFile("../../gc/ssa.go")
-	if err != nil {
-		log.Fatalf("can't read ../../gc/ssa.go: %v", err)
-	}
 	for _, a := range archs {
-		if a.name == "generic" {
+		if a.genfile == "" {
 			continue
 		}
+
+		src, err := ioutil.ReadFile(a.genfile)
+		if err != nil {
+			log.Fatalf("can't read %s: %v", a.genfile, err)
+		}
+
 		for _, v := range a.ops {
 			pattern := fmt.Sprintf("\\Wssa[.]Op%s%s\\W", a.name, v.name)
-			match, err := regexp.Match(pattern, ssa)
+			match, err := regexp.Match(pattern, src)
 			if err != nil {
 				log.Fatalf("bad opcode regexp %s: %v", pattern, err)
 			}
 			if !match {
-				log.Fatalf("Op%s%s has no code generation in ../../gc/ssa.go", a.name, v.name)
+				log.Fatalf("Op%s%s has no code generation in %s", a.name, v.name, a.genfile)
 			}
 		}
 	}