1 files changed, 97 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/ssa/deadstore_test.go b/src/cmd/compile/internal/ssa/deadstore_test.go
new file mode 100644
index 0000000000..9ded8bd6e6
--- /dev/null
+++ b/src/cmd/compile/internal/ssa/deadstore_test.go
@@ -0,0 +1,97 @@
+// 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 "testing"
+
+func TestDeadStore(t *testing.T) {
+	c := testConfig(t)
+	elemType := &TypeImpl{Size_: 8, Name: "testtype"}
+	ptrType := &TypeImpl{Size_: 8, Ptr: true, Name: "testptr", Elem_: elemType} // dummy for testing
+	fun := Fun(c, "entry",
+		Bloc("entry",
+			Valu("start", OpInitMem, TypeMem, 0, nil),
+			Valu("sb", OpSB, TypeInvalid, 0, nil),
+			Valu("v", OpConstBool, TypeBool, 1, nil),
+			Valu("addr1", OpAddr, ptrType, 0, nil, "sb"),
+			Valu("addr2", OpAddr, ptrType, 0, nil, "sb"),
+			Valu("addr3", OpAddr, ptrType, 0, nil, "sb"),
+			Valu("zero1", OpZero, TypeMem, 8, nil, "addr3", "start"),
+			Valu("store1", OpStore, TypeMem, 1, nil, "addr1", "v", "zero1"),
+			Valu("store2", OpStore, TypeMem, 1, nil, "addr2", "v", "store1"),
+			Valu("store3", OpStore, TypeMem, 1, nil, "addr1", "v", "store2"),
+			Valu("store4", OpStore, TypeMem, 1, nil, "addr3", "v", "store3"),
+			Goto("exit")),
+		Bloc("exit",
+			Exit("store3")))
+
+	CheckFunc(fun.f)
+	dse(fun.f)
+	CheckFunc(fun.f)
+
+	v1 := fun.values["store1"]
+	if v1.Op != OpCopy {
+		t.Errorf("dead store not removed")
+	}
+
+	v2 := fun.values["zero1"]
+	if v2.Op != OpCopy {
+		t.Errorf("dead store (zero) not removed")
+	}
+}
+func TestDeadStorePhi(t *testing.T) {
+	// make sure we don't get into an infinite loop with phi values.
+	c := testConfig(t)
+	ptrType := &TypeImpl{Size_: 8, Ptr: true, Name: "testptr"} // dummy for testing
+	fun := Fun(c, "entry",
+		Bloc("entry",
+			Valu("start", OpInitMem, TypeMem, 0, nil),
+			Valu("sb", OpSB, TypeInvalid, 0, nil),
+			Valu("v", OpConstBool, TypeBool, 1, nil),
+			Valu("addr", OpAddr, ptrType, 0, nil, "sb"),
+			Goto("loop")),
+		Bloc("loop",
+			Valu("phi", OpPhi, TypeMem, 0, nil, "start", "store"),
+			Valu("store", OpStore, TypeMem, 1, nil, "addr", "v", "phi"),
+			If("v", "loop", "exit")),
+		Bloc("exit",
+			Exit("store")))
+
+	CheckFunc(fun.f)
+	dse(fun.f)
+	CheckFunc(fun.f)
+}
+
+func TestDeadStoreTypes(t *testing.T) {
+	// Make sure a narrow store can't shadow a wider one.  We test an even
+	// stronger restriction, that one store can't shadow another unless the
+	// types of the address fields are identical (where identicalness is
+	// decided by the CSE pass).
+	c := testConfig(t)
+	t1 := &TypeImpl{Size_: 8, Ptr: true, Name: "t1"}
+	t2 := &TypeImpl{Size_: 4, Ptr: true, Name: "t2"}
+	fun := Fun(c, "entry",
+		Bloc("entry",
+			Valu("start", OpInitMem, TypeMem, 0, nil),
+			Valu("sb", OpSB, TypeInvalid, 0, nil),
+			Valu("v", OpConstBool, TypeBool, 1, nil),
+			Valu("addr1", OpAddr, t1, 0, nil, "sb"),
+			Valu("addr2", OpAddr, t2, 0, nil, "sb"),
+			Valu("store1", OpStore, TypeMem, 1, nil, "addr1", "v", "start"),
+			Valu("store2", OpStore, TypeMem, 1, nil, "addr2", "v", "store1"),
+			Goto("exit")),
+		Bloc("exit",
+			Exit("store2")))
+
+	CheckFunc(fun.f)
+	cse(fun.f)
+	dse(fun.f)
+	CheckFunc(fun.f)
+
+	v := fun.values["store1"]
+	if v.Op == OpCopy {
+		t.Errorf("store %s incorrectly removed", v)
+	}
+}