[dev.ssa] cmd/compile/internal/gc: reduce genValue redundancy

Add an asm field to opcodeTable containing the Prog's as field.
Then instructions that fill the Prog the same way can be collapsed
into a single switch case.

I'm still thinking of a better way to reduce redundancy, but
I think this might be a good temporary solution to prevent duplication
from getting out of control. What do you think?

Change-Id: I0c4a0992741f908bd357ee2707edb82e76e4ce61
Reviewed-on: https://go-review.googlesource.com/11130
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Keith Randall <khr@golang.org>

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

@@ -9,6 +9,8 @@ package main
 
 import (
 	"bytes"
+	"cmd/internal/obj"
+	"cmd/internal/obj/x86"
 	"fmt"
 	"go/format"
 	"io/ioutil"
@@ -25,6 +27,7 @@ type arch struct {
 type opData struct {
 	name string
 	reg  regInfo
+	asm  int16
 }
 
 type blockData struct {
@@ -60,12 +63,15 @@ func main() {
 	genOp()
 	genLower()
 }
+
 func genOp() {
 	w := new(bytes.Buffer)
 	fmt.Fprintf(w, "// autogenerated: do not edit!\n")
 	fmt.Fprintf(w, "// generated from gen/*Ops.go\n")
 	fmt.Fprintln(w, "package ssa")
 
+	fmt.Fprintln(w, "import \"cmd/internal/obj/x86\"")
+
 	// generate Block* declarations
 	fmt.Fprintln(w, "const (")
 	fmt.Fprintln(w, "blockInvalid BlockKind = iota")
@@ -108,6 +114,9 @@ func genOp() {
 		for _, v := range a.ops {
 			fmt.Fprintln(w, "{")
 			fmt.Fprintf(w, "name:\"%s\",\n", v.name)
+			if v.asm != 0 {
+				fmt.Fprintf(w, "asm: x86.A%s,\n", x86.Anames[v.asm-obj.ABaseAMD64])
+			}
 			fmt.Fprintln(w, "reg:regInfo{")
 			fmt.Fprintln(w, "inputs: []regMask{")
 			for _, r := range v.reg.inputs {
@@ -129,6 +138,8 @@ func genOp() {
 	}
 	fmt.Fprintln(w, "}")
 
+	fmt.Fprintln(w, "func (o Op) Asm() int {return opcodeTable[o].asm}")
+
 	// generate op string method
 	fmt.Fprintln(w, "func (o Op) String() string {return opcodeTable[o].name }")