1 files changed, 161 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/ssa/deadcode_test.go b/src/cmd/compile/internal/ssa/deadcode_test.go
new file mode 100644
index 0000000..5777b84
--- /dev/null
+++ b/src/cmd/compile/internal/ssa/deadcode_test.go
@@ -0,0 +1,161 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssa
+
+import (
+	"cmd/compile/internal/types"
+	"fmt"
+	"strconv"
+	"testing"
+)
+
+func TestDeadLoop(t *testing.T) {
+	c := testConfig(t)
+	fun := c.Fun("entry",
+		Bloc("entry",
+			Valu("mem", OpInitMem, types.TypeMem, 0, nil),
+			Goto("exit")),
+		Bloc("exit",
+			Exit("mem")),
+		// dead loop
+		Bloc("deadblock",
+			// dead value in dead block
+			Valu("deadval", OpConstBool, c.config.Types.Bool, 1, nil),
+			If("deadval", "deadblock", "exit")))
+
+	CheckFunc(fun.f)
+	Deadcode(fun.f)
+	CheckFunc(fun.f)
+
+	for _, b := range fun.f.Blocks {
+		if b == fun.blocks["deadblock"] {
+			t.Errorf("dead block not removed")
+		}
+		for _, v := range b.Values {
+			if v == fun.values["deadval"] {
+				t.Errorf("control value of dead block not removed")
+			}
+		}
+	}
+}
+
+func TestDeadValue(t *testing.T) {
+	c := testConfig(t)
+	fun := c.Fun("entry",
+		Bloc("entry",
+			Valu("mem", OpInitMem, types.TypeMem, 0, nil),
+			Valu("deadval", OpConst64, c.config.Types.Int64, 37, nil),
+			Goto("exit")),
+		Bloc("exit",
+			Exit("mem")))
+
+	CheckFunc(fun.f)
+	Deadcode(fun.f)
+	CheckFunc(fun.f)
+
+	for _, b := range fun.f.Blocks {
+		for _, v := range b.Values {
+			if v == fun.values["deadval"] {
+				t.Errorf("dead value not removed")
+			}
+		}
+	}
+}
+
+func TestNeverTaken(t *testing.T) {
+	c := testConfig(t)
+	fun := c.Fun("entry",
+		Bloc("entry",
+			Valu("cond", OpConstBool, c.config.Types.Bool, 0, nil),
+			Valu("mem", OpInitMem, types.TypeMem, 0, nil),
+			If("cond", "then", "else")),
+		Bloc("then",
+			Goto("exit")),
+		Bloc("else",
+			Goto("exit")),
+		Bloc("exit",
+			Exit("mem")))
+
+	CheckFunc(fun.f)
+	Opt(fun.f)
+	Deadcode(fun.f)
+	CheckFunc(fun.f)
+
+	if fun.blocks["entry"].Kind != BlockPlain {
+		t.Errorf("if(false) not simplified")
+	}
+	for _, b := range fun.f.Blocks {
+		if b == fun.blocks["then"] {
+			t.Errorf("then block still present")
+		}
+		for _, v := range b.Values {
+			if v == fun.values["cond"] {
+				t.Errorf("constant condition still present")
+			}
+		}
+	}
+
+}
+
+func TestNestedDeadBlocks(t *testing.T) {
+	c := testConfig(t)
+	fun := c.Fun("entry",
+		Bloc("entry",
+			Valu("mem", OpInitMem, types.TypeMem, 0, nil),
+			Valu("cond", OpConstBool, c.config.Types.Bool, 0, nil),
+			If("cond", "b2", "b4")),
+		Bloc("b2",
+			If("cond", "b3", "b4")),
+		Bloc("b3",
+			If("cond", "b3", "b4")),
+		Bloc("b4",
+			If("cond", "b3", "exit")),
+		Bloc("exit",
+			Exit("mem")))
+
+	CheckFunc(fun.f)
+	Opt(fun.f)
+	CheckFunc(fun.f)
+	Deadcode(fun.f)
+	CheckFunc(fun.f)
+	if fun.blocks["entry"].Kind != BlockPlain {
+		t.Errorf("if(false) not simplified")
+	}
+	for _, b := range fun.f.Blocks {
+		if b == fun.blocks["b2"] {
+			t.Errorf("b2 block still present")
+		}
+		if b == fun.blocks["b3"] {
+			t.Errorf("b3 block still present")
+		}
+		for _, v := range b.Values {
+			if v == fun.values["cond"] {
+				t.Errorf("constant condition still present")
+			}
+		}
+	}
+}
+
+func BenchmarkDeadCode(b *testing.B) {
+	for _, n := range [...]int{1, 10, 100, 1000, 10000, 100000, 200000} {
+		b.Run(strconv.Itoa(n), func(b *testing.B) {
+			c := testConfig(b)
+			blocks := make([]bloc, 0, n+2)
+			blocks = append(blocks,
+				Bloc("entry",
+					Valu("mem", OpInitMem, types.TypeMem, 0, nil),
+					Goto("exit")))
+			blocks = append(blocks, Bloc("exit", Exit("mem")))
+			for i := 0; i < n; i++ {
+				blocks = append(blocks, Bloc(fmt.Sprintf("dead%d", i), Goto("exit")))
+			}
+			b.ResetTimer()
+			for i := 0; i < b.N; i++ {
+				fun := c.Fun("entry", blocks...)
+				Deadcode(fun.f)
+			}
+		})
+	}
+}