github.com/gocuntian/go@v0.0.0-20160610041250-fee02d270bf8/src/cmd/compile/internal/ssa/deadstore_test.go (about)

     1  // Copyright 2015 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package ssa
     6  
     7  import "testing"
     8  
     9  func TestDeadStore(t *testing.T) {
    10  	c := testConfig(t)
    11  	elemType := &TypeImpl{Size_: 8, Name: "testtype"}
    12  	ptrType := &TypeImpl{Size_: 8, Ptr: true, Name: "testptr", Elem_: elemType} // dummy for testing
    13  	fun := Fun(c, "entry",
    14  		Bloc("entry",
    15  			Valu("start", OpInitMem, TypeMem, 0, nil),
    16  			Valu("sb", OpSB, TypeInvalid, 0, nil),
    17  			Valu("v", OpConstBool, TypeBool, 1, nil),
    18  			Valu("addr1", OpAddr, ptrType, 0, nil, "sb"),
    19  			Valu("addr2", OpAddr, ptrType, 0, nil, "sb"),
    20  			Valu("addr3", OpAddr, ptrType, 0, nil, "sb"),
    21  			Valu("zero1", OpZero, TypeMem, 8, nil, "addr3", "start"),
    22  			Valu("store1", OpStore, TypeMem, 1, nil, "addr1", "v", "zero1"),
    23  			Valu("store2", OpStore, TypeMem, 1, nil, "addr2", "v", "store1"),
    24  			Valu("store3", OpStore, TypeMem, 1, nil, "addr1", "v", "store2"),
    25  			Valu("store4", OpStore, TypeMem, 1, nil, "addr3", "v", "store3"),
    26  			Goto("exit")),
    27  		Bloc("exit",
    28  			Exit("store3")))
    29  
    30  	CheckFunc(fun.f)
    31  	dse(fun.f)
    32  	CheckFunc(fun.f)
    33  
    34  	v1 := fun.values["store1"]
    35  	if v1.Op != OpCopy {
    36  		t.Errorf("dead store not removed")
    37  	}
    38  
    39  	v2 := fun.values["zero1"]
    40  	if v2.Op != OpCopy {
    41  		t.Errorf("dead store (zero) not removed")
    42  	}
    43  }
    44  func TestDeadStorePhi(t *testing.T) {
    45  	// make sure we don't get into an infinite loop with phi values.
    46  	c := testConfig(t)
    47  	ptrType := &TypeImpl{Size_: 8, Ptr: true, Name: "testptr"} // dummy for testing
    48  	fun := Fun(c, "entry",
    49  		Bloc("entry",
    50  			Valu("start", OpInitMem, TypeMem, 0, nil),
    51  			Valu("sb", OpSB, TypeInvalid, 0, nil),
    52  			Valu("v", OpConstBool, TypeBool, 1, nil),
    53  			Valu("addr", OpAddr, ptrType, 0, nil, "sb"),
    54  			Goto("loop")),
    55  		Bloc("loop",
    56  			Valu("phi", OpPhi, TypeMem, 0, nil, "start", "store"),
    57  			Valu("store", OpStore, TypeMem, 1, nil, "addr", "v", "phi"),
    58  			If("v", "loop", "exit")),
    59  		Bloc("exit",
    60  			Exit("store")))
    61  
    62  	CheckFunc(fun.f)
    63  	dse(fun.f)
    64  	CheckFunc(fun.f)
    65  }
    66  
    67  func TestDeadStoreTypes(t *testing.T) {
    68  	// Make sure a narrow store can't shadow a wider one. We test an even
    69  	// stronger restriction, that one store can't shadow another unless the
    70  	// types of the address fields are identical (where identicalness is
    71  	// decided by the CSE pass).
    72  	c := testConfig(t)
    73  	t1 := &TypeImpl{Size_: 8, Ptr: true, Name: "t1"}
    74  	t2 := &TypeImpl{Size_: 4, Ptr: true, Name: "t2"}
    75  	fun := Fun(c, "entry",
    76  		Bloc("entry",
    77  			Valu("start", OpInitMem, TypeMem, 0, nil),
    78  			Valu("sb", OpSB, TypeInvalid, 0, nil),
    79  			Valu("v", OpConstBool, TypeBool, 1, nil),
    80  			Valu("addr1", OpAddr, t1, 0, nil, "sb"),
    81  			Valu("addr2", OpAddr, t2, 0, nil, "sb"),
    82  			Valu("store1", OpStore, TypeMem, 1, nil, "addr1", "v", "start"),
    83  			Valu("store2", OpStore, TypeMem, 1, nil, "addr2", "v", "store1"),
    84  			Goto("exit")),
    85  		Bloc("exit",
    86  			Exit("store2")))
    87  
    88  	CheckFunc(fun.f)
    89  	cse(fun.f)
    90  	dse(fun.f)
    91  	CheckFunc(fun.f)
    92  
    93  	v := fun.values["store1"]
    94  	if v.Op == OpCopy {
    95  		t.Errorf("store %s incorrectly removed", v)
    96  	}
    97  }