diff --git a/internal/graphicscommand/command.go b/internal/graphicscommand/command.go
index aac2ed4c6..496444fbd 100644
--- a/internal/graphicscommand/command.go
+++ b/internal/graphicscommand/command.go
@@ -111,18 +111,7 @@ func (q *commandQueue) EnqueueDrawTrianglesCommand(dst *Image, srcs [graphics.Sh
 	uniforms = prependPreservedUniforms(uniforms, dst, srcs, offsets, dstRegion, srcRegion)
 
 	// Remove unused uniform variables so that more commands can be merged.
-	uvs := map[int]struct{}{}
-	for _, i := range shader.ir.ReachableUniformVariablesFromBlock(shader.ir.VertexFunc.Block) {
-		uvs[i] = struct{}{}
-	}
-	for _, i := range shader.ir.ReachableUniformVariablesFromBlock(shader.ir.FragmentFunc.Block) {
-		uvs[i] = struct{}{}
-	}
-	for i := range uniforms {
-		if _, ok := uvs[i]; !ok {
-			uniforms[i] = nil
-		}
-	}
+	shader.ir.FilterUniformVariables(uniforms)
 
 	// TODO: If dst is the screen, reorder the command to be the last.
 	if !split && 0 < len(q.commands) {
diff --git a/internal/shaderir/export_test.go b/internal/shaderir/export_test.go
new file mode 100644
index 000000000..349041473
--- /dev/null
+++ b/internal/shaderir/export_test.go
@@ -0,0 +1,19 @@
+// Copyright 2022 The Ebitengine Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package shaderir
+
+func (p *Program) ReachableUniformVariablesFromBlock(block *Block) []int {
+	return p.reachableUniformVariablesFromBlock(block)
+}
diff --git a/internal/shaderir/program.go b/internal/shaderir/program.go
index 283803c51..371107325 100644
--- a/internal/shaderir/program.go
+++ b/internal/shaderir/program.go
@@ -31,6 +31,8 @@ type Program struct {
 	Funcs        []Func
 	VertexFunc   VertexFunc
 	FragmentFunc FragmentFunc
+
+	reachableUniforms map[int]struct{}
 }
 
 type Func struct {
@@ -420,7 +422,7 @@ func walkExprsInExpr(f func(expr *Expr), expr *Expr) {
 	}
 }
 
-func (p *Program) ReachableUniformVariablesFromBlock(block *Block) []int {
+func (p *Program) reachableUniformVariablesFromBlock(block *Block) []int {
 	indexToFunc := map[int]*Func{}
 	for _, f := range p.Funcs {
 		f := f
@@ -451,3 +453,20 @@ func (p *Program) ReachableUniformVariablesFromBlock(block *Block) []int {
 	sort.Ints(is)
 	return is
 }
+
+func (p *Program) FilterUniformVariables(uniforms [][]float32) {
+	if p.reachableUniforms == nil {
+		p.reachableUniforms = map[int]struct{}{}
+		for _, i := range p.reachableUniformVariablesFromBlock(p.VertexFunc.Block) {
+			p.reachableUniforms[i] = struct{}{}
+		}
+		for _, i := range p.reachableUniformVariablesFromBlock(p.FragmentFunc.Block) {
+			p.reachableUniforms[i] = struct{}{}
+		}
+	}
+	for i := range uniforms {
+		if _, ok := p.reachableUniforms[i]; !ok {
+			uniforms[i] = nil
+		}
+	}
+}
diff --git a/internal/shader/reachable_test.go b/internal/shaderir/reachable_test.go
similarity index 79%
rename from internal/shader/reachable_test.go
rename to internal/shaderir/reachable_test.go
index 544934d9c..5a4aec2ed 100644
--- a/internal/shader/reachable_test.go
+++ b/internal/shaderir/reachable_test.go
@@ -12,12 +12,32 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package shader_test
+package shaderir_test
 
 import (
+	"go/parser"
+	"go/token"
 	"testing"
+
+	"github.com/hajimehoshi/ebiten/v2/internal/shader"
+	"github.com/hajimehoshi/ebiten/v2/internal/shaderir"
 )
 
+func compileToIR(src []byte) (*shaderir.Program, error) {
+	fset := token.NewFileSet()
+	f, err := parser.ParseFile(fset, "", src, parser.AllErrors)
+	if err != nil {
+		return nil, err
+	}
+
+	ir, err := shader.Compile(fset, f, "Vertex", "Fragment", 0)
+	if err != nil {
+		return nil, err
+	}
+
+	return ir, nil
+}
+
 func areIntSlicesEqual(a, b []int) bool {
 	if len(a) != len(b) {
 		return false