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branchelim_test.go
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// Copyright 2017 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"
"testing"
)
// Test that a trivial 'if' is eliminated
func TestBranchElimIf(t *testing.T) {
var testData = []struct {
arch string
intType string
ok bool
}{
{"arm64", "int32", true},
{"amd64", "int32", true},
{"amd64", "int8", false},
}
for _, data := range testData {
t.Run(data.arch+"/"+data.intType, func(t *testing.T) {
c := testConfigArch(t, data.arch)
boolType := c.config.Types.Bool
var intType *types.Type
switch data.intType {
case "int32":
intType = c.config.Types.Int32
case "int8":
intType = c.config.Types.Int8
default:
t.Fatal("invalid integer type:", data.intType)
}
fun := c.Fun("entry",
Bloc("entry",
Valu("start", OpInitMem, types.TypeMem, 0, nil),
Valu("sb", OpSB, c.config.Types.Uintptr, 0, nil),
Valu("const1", OpConst32, intType, 1, nil),
Valu("const2", OpConst32, intType, 2, nil),
Valu("addr", OpAddr, boolType.PtrTo(), 0, nil, "sb"),
Valu("cond", OpLoad, boolType, 0, nil, "addr", "start"),
If("cond", "b2", "b3")),
Bloc("b2",
Goto("b3")),
Bloc("b3",
Valu("phi", OpPhi, intType, 0, nil, "const1", "const2"),
Valu("retstore", OpStore, types.TypeMem, 0, nil, "phi", "sb", "start"),
Exit("retstore")))
CheckFunc(fun.f)
branchelim(fun.f)
CheckFunc(fun.f)
Deadcode(fun.f)
CheckFunc(fun.f)
if data.ok {
if len(fun.f.Blocks) != 1 {
t.Fatalf("expected 1 block after branchelim and deadcode; found %d", len(fun.f.Blocks))
}
if fun.values["phi"].Op != OpCondSelect {
t.Fatalf("expected phi op to be CondSelect; found op %s", fun.values["phi"].Op)
}
if fun.values["phi"].Args[2] != fun.values["cond"] {
t.Errorf("expected CondSelect condition to be %s; found %s", fun.values["cond"], fun.values["phi"].Args[2])
}
if fun.blocks["entry"].Kind != BlockExit {
t.Errorf("expected entry to be BlockExit; found kind %s", fun.blocks["entry"].Kind.String())
}
} else {
if len(fun.f.Blocks) != 3 {
t.Fatalf("expected 3 block after branchelim and deadcode; found %d", len(fun.f.Blocks))
}
}
})
}
}
// Test that a trivial if/else is eliminated
func TestBranchElimIfElse(t *testing.T) {
for _, arch := range []string{"arm64", "amd64"} {
t.Run(arch, func(t *testing.T) {
c := testConfigArch(t, arch)
boolType := c.config.Types.Bool
intType := c.config.Types.Int32
fun := c.Fun("entry",
Bloc("entry",
Valu("start", OpInitMem, types.TypeMem, 0, nil),
Valu("sb", OpSB, c.config.Types.Uintptr, 0, nil),
Valu("const1", OpConst32, intType, 1, nil),
Valu("const2", OpConst32, intType, 2, nil),
Valu("addr", OpAddr, boolType.PtrTo(), 0, nil, "sb"),
Valu("cond", OpLoad, boolType, 0, nil, "addr", "start"),
If("cond", "b2", "b3")),
Bloc("b2",
Goto("b4")),
Bloc("b3",
Goto("b4")),
Bloc("b4",
Valu("phi", OpPhi, intType, 0, nil, "const1", "const2"),
Valu("retstore", OpStore, types.TypeMem, 0, nil, "phi", "sb", "start"),
Exit("retstore")))
CheckFunc(fun.f)
branchelim(fun.f)
CheckFunc(fun.f)
Deadcode(fun.f)
CheckFunc(fun.f)
if len(fun.f.Blocks) != 1 {
t.Fatalf("expected 1 block after branchelim; found %d", len(fun.f.Blocks))
}
if fun.values["phi"].Op != OpCondSelect {
t.Fatalf("expected phi op to be CondSelect; found op %s", fun.values["phi"].Op)
}
if fun.values["phi"].Args[2] != fun.values["cond"] {
t.Errorf("expected CondSelect condition to be %s; found %s", fun.values["cond"], fun.values["phi"].Args[2])
}
if fun.blocks["entry"].Kind != BlockExit {
t.Errorf("expected entry to be BlockExit; found kind %s", fun.blocks["entry"].Kind.String())
}
})
}
}
// Test that an if/else CFG that loops back
// into itself does *not* get eliminated.
func TestNoBranchElimLoop(t *testing.T) {
for _, arch := range []string{"arm64", "amd64"} {
t.Run(arch, func(t *testing.T) {
c := testConfigArch(t, arch)
boolType := c.config.Types.Bool
intType := c.config.Types.Int32
// The control flow here is totally bogus,
// but a dead cycle seems like the only plausible
// way to arrive at a diamond CFG that is also a loop.
fun := c.Fun("entry",
Bloc("entry",
Valu("start", OpInitMem, types.TypeMem, 0, nil),
Valu("sb", OpSB, c.config.Types.Uintptr, 0, nil),
Valu("const2", OpConst32, intType, 2, nil),
Valu("const3", OpConst32, intType, 3, nil),
Goto("b5")),
Bloc("b2",
Valu("addr", OpAddr, boolType.PtrTo(), 0, nil, "sb"),
Valu("cond", OpLoad, boolType, 0, nil, "addr", "start"),
Valu("phi", OpPhi, intType, 0, nil, "const2", "const3"),
If("cond", "b3", "b4")),
Bloc("b3",
Goto("b2")),
Bloc("b4",
Goto("b2")),
Bloc("b5",
Exit("start")))
CheckFunc(fun.f)
branchelim(fun.f)
CheckFunc(fun.f)
if len(fun.f.Blocks) != 5 {
t.Errorf("expected 5 block after branchelim; found %d", len(fun.f.Blocks))
}
if fun.values["phi"].Op != OpPhi {
t.Errorf("expected phi op to be CondSelect; found op %s", fun.values["phi"].Op)
}
})
}
}