shaderir: Use constant.Value for number literals

Updates #1190

internal/shader/shader.go

@@ -17,8 +17,8 @@ package shader
 import (
 	"fmt"
 	"go/ast"
+	gconstant "go/constant"
 	"go/token"
-	"strconv"
 	"strings"
 
 	"github.com/hajimehoshi/ebiten/internal/shaderir"
@@ -759,27 +759,17 @@ func (cs *compileState) parseExpr(block *block, expr ast.Expr) ([]shaderir.Expr,
 	case *ast.BasicLit:
 		switch e.Kind {
 		case token.INT:
-			v, err := strconv.ParseInt(e.Value, 10, 32)
-			if err != nil {
-				cs.addError(e.Pos(), fmt.Sprintf("unexpected literal: %s", e.Value))
-				return nil, nil, nil
-			}
 			return []shaderir.Expr{
 				{
-					Type: shaderir.IntExpr,
-					Int:  int32(v),
+					Type:  shaderir.NumberExpr,
+					Const: gconstant.MakeFromLiteral(e.Value, e.Kind, 0),
 				},
 			}, []shaderir.Type{{Main: shaderir.Int}}, nil
 		case token.FLOAT:
-			v, err := strconv.ParseFloat(e.Value, 32)
-			if err != nil {
-				cs.addError(e.Pos(), fmt.Sprintf("unexpected literal: %s", e.Value))
-				return nil, nil, nil
-			}
 			return []shaderir.Expr{
 				{
-					Type:  shaderir.FloatExpr,
-					Float: float32(v),
+					Type:  shaderir.NumberExpr,
+					Const: gconstant.MakeFromLiteral(e.Value, e.Kind, 0),
 				},
 			}, []shaderir.Type{{Main: shaderir.Float}}, nil
 		default:

internal/shader/testdata/assign.expected.vs

@@ -1,7 +1,7 @@
 void F0(in vec2 l0, out vec4 l1) {
 	float l2 = float(0);
-	l2 = 0.000000000e+00;
-	l2 = (l2) + (1.000000000e+00);
+	l2 = 0.0;
+	l2 = (l2) + (1.0);
 	l1 = vec4(l0, l2, l2);
 	return;
 }

internal/shader/testdata/define_type.expected.vs

@@ -1,6 +1,6 @@
 void F0(in vec2 l0, out vec4 l1) {
 	vec4 l2 = vec4(0);
-	l2 = (vec4(0.000000000e+00)) * (vec4(0.000000000e+00));
+	l2 = (vec4(0.0)) * (vec4(0.0));
 	l1 = l2;
 	return;
 }

internal/shaderir/glsl.go

@@ -16,6 +16,7 @@ package shaderir
 
 import (
 	"fmt"
+	"go/constant"
 	"strings"
 )
 
@@ -234,11 +235,24 @@ func (p *Program) glslBlock(b *Block, level int, localVarIndex int) []string {
 	var glslExpr func(e *Expr) string
 	glslExpr = func(e *Expr) string {
 		switch e.Type {
-		case IntExpr:
-			// TODO: Cast to int if the context requries integers.
-			return fmt.Sprintf("%d.0", e.Int)
-		case FloatExpr:
-			return fmt.Sprintf("%.9e", e.Float)
+		case NumberExpr:
+			switch e.ConstType {
+			case ConstTypeNone, ConstTypeFloat:
+				if i := constant.ToInt(e.Const); i.Kind() == constant.Int {
+					x, _ := constant.Int64Val(i)
+					return fmt.Sprintf("%d.0", x)
+				}
+				if i := constant.ToFloat(e.Const); i.Kind() == constant.Float {
+					x, _ := constant.Float64Val(i)
+					return fmt.Sprintf("%.9e", x)
+				}
+			case ConstTypeInt:
+				if i := constant.ToInt(e.Const); i.Kind() == constant.Int {
+					x, _ := constant.Int64Val(i)
+					return fmt.Sprintf("%d", x)
+				}
+			}
+			return fmt.Sprintf("?(unexpected literal: %s)", e.Const)
 		case UniformVariable:
 			return fmt.Sprintf("U%d", e.Index)
 		case LocalVariable:
@@ -321,6 +335,7 @@ func (p *Program) glslBlock(b *Block, level int, localVarIndex int) []string {
 			lines = append(lines, p.glslBlock(&s.Blocks[0], level+1, localVarIndex)...)
 			lines = append(lines, idt+"}")
 		case Assign:
+			// TODO: Give an appropriate context
 			lines = append(lines, fmt.Sprintf("%s%s = %s;", idt, glslExpr(&s.Exprs[0]), glslExpr(&s.Exprs[1])))
 		case If:
 			lines = append(lines, fmt.Sprintf("%sif (%s) {", idt, glslExpr(&s.Exprs[0])))
@@ -366,6 +381,7 @@ func (p *Program) glslBlock(b *Block, level int, localVarIndex int) []string {
 			if len(s.Exprs) == 0 {
 				lines = append(lines, idt+"return;")
 			} else {
+				// TODO: Give an appropriate context.
 				lines = append(lines, fmt.Sprintf("%sreturn %s;", idt, glslExpr(&s.Exprs[0])))
 			}
 		case Discard:

internal/shaderir/ir_test.go

@@ -15,6 +15,7 @@
 package shaderir_test
 
 import (
+	"go/constant"
 	"testing"
 
 	. "github.com/hajimehoshi/ebiten/internal/shaderir"
@@ -76,8 +77,8 @@ func forStmt(init, end int, op Op, delta int, block Block) Stmt {
 
 func floatExpr(value float32) Expr {
 	return Expr{
-		Type:  FloatExpr,
-		Float: value,
+		Type:  NumberExpr,
+		Const: constant.MakeFloat64(float64(value)),
 	}
 }
 
@@ -561,14 +562,14 @@ varying vec3 V0;`,
 				},
 			},
 			GlslVS: `void F0(in float l0, in float l1, out float l2) {
-	if ((l0) == (0.000000000e+00)) {
+	if ((l0) == (0.0)) {
 		l2 = l0;
 	} else {
 		l2 = l1;
 	}
 }`,
 			GlslFS: `void F0(in float l0, in float l1, out float l2) {
-	if ((l0) == (0.000000000e+00)) {
+	if ((l0) == (0.0)) {
 		l2 = l0;
 	} else {
 		l2 = l1;

internal/shaderir/program.go

@@ -16,6 +16,7 @@
 package shaderir
 
 import (
+	"go/constant"
 	"go/token"
 )
 
@@ -85,11 +86,20 @@ const (
 	Discard
 )
 
+type ConstType int
+
+const (
+	ConstTypeNone ConstType = iota
+	ConstTypeBool
+	ConstTypeInt
+	ConstTypeFloat
+)
+
 type Expr struct {
 	Type        ExprType
 	Exprs       []Expr
-	Int         int32
-	Float       float32
+	Const       constant.Value
+	ConstType   ConstType
 	BuiltinFunc BuiltinFunc
 	Swizzling   string
 	Index       int
@@ -99,8 +109,7 @@ type Expr struct {
 type ExprType int
 
 const (
-	IntExpr ExprType = iota
-	FloatExpr
+	NumberExpr ExprType = iota
 	UniformVariable
 	LocalVariable
 	StructMember