/*
* Copyright 2010 The Closure Compiler 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 com.google.javascript.jscomp;
import com.google.common.collect.ImmutableSet;
import com.google.javascript.jscomp.CompilerOptions.LanguageMode;
import com.google.javascript.jscomp.NodeTraversal.AbstractPostOrderCallback;
import com.google.javascript.jscomp.SideEffectsAnalysis.LocationAbstractionMode;
import com.google.javascript.rhino.Node;
/**
* Tests for {@link SideEffectsAnalysis}.
*
* @author dcc@google.com (Devin Coughlin)
*
*/
public final class SideEffectsAnalysisTest extends CompilerTestCase {
private static final String SHARED_EXTERNS = "var arguments = [];";
LocationAbstractionMode currentLocationAbstractionIdentifier;
SideEffectsAnalysis currentAnalysis = null;
Node currentJsRoot = null;
@Override
protected CompilerPass getProcessor(final Compiler compiler) {
currentAnalysis = new SideEffectsAnalysis(compiler,
currentLocationAbstractionIdentifier);
return new CompilerPass() {
@Override
public void process(Node externs, Node root) {
if (currentLocationAbstractionIdentifier == LocationAbstractionMode.VISIBILITY_BASED) {
// Run var when using the visibility abstraction
// because it is unsound if it fails.
final VarCheck varCheck = new VarCheck(compiler);
varCheck.process(externs, root);
}
currentAnalysis.process(externs, root);
}
};
}
@Override
public void setUp() throws Exception {
super.setUp();
currentAnalysis = null;
}
public void testDegenerateSafeMoves() {
// Env is empty
assertSafeMoveDegenerate("src: 1; env: ; dest: 3;");
// Src and env pure
assertSafeMoveDegenerate("src: 1; env: 2; dest: 3;");
// Only refs
assertSafeMoveDegenerate("src: 1; env: x; dest: 3;");
assertSafeMoveDegenerate("src: x; env: 1; dest: 3;");
// Only mods
assertSafeMoveDegenerate("src: 1; env: x++; dest: 3;");
assertSafeMoveDegenerate("src: x++; env: 1; dest: 3;");
}
public void testVisibilitySafeMoves() {
// Env is empty
assertSafeMoveVisibility("src: 1; env: ; dest: 3;");
// Src and env pure
assertSafeMoveVisibility("src: 1; env: 2; dest: 3;");
// Only refs
assertSafeMoveVisibility("var x; src: 1; env: x; dest: 3;");
assertSafeMoveVisibility("var x; src: x; env: 1; dest: 3;");
// Only mods
assertSafeMoveVisibility("var x; src: 1; env: x++; dest: 3;");
assertSafeMoveVisibility("var x; src: x++; env: 1; dest: 3;");
// Source references global, env changes local
assertSafeMoveVisibility(LINE_JOINER.join(
"var x;",
"function f(){",
" var y;",
" src: x;",
" env: y++;",
" dest: 3;",
"}"));
// Source changes global, env refs local
assertSafeMoveVisibility(LINE_JOINER.join(
"var x;",
"function f(){",
" var y;",
" src: x++;",
" env: y;",
" dest: 3;",
"}"));
// Source references global, env changes local with shadowing
assertSafeMoveVisibility(LINE_JOINER.join(
"var x;",
"var y;",
"function f(){",
" var y;",
" src: x;",
" env: y++;",
" dest: 3;",
"}"));
// Source changes global, env refs local with shadowing
assertSafeMoveVisibility(LINE_JOINER.join(
"var x;",
"var y;",
"function f(){",
" var y;",
" src: x++;",
" env: y;",
" dest: 3;",
"}"));
// Source references captured local, env changes local
assertSafeMoveVisibility(LINE_JOINER.join(
"function f(){",
" var x;",
" var y;",
" src: x;",
" env: y++;",
" dest: 3;",
" function inner() {",
" x",
" }",
"}"));
// Source changes captured local, env refs local
assertSafeMoveVisibility(LINE_JOINER.join(
"function f(){",
" var x;",
" var y;",
" src: x++;",
" env: y;",
" dest: 3;",
" function inner() {",
" x",
" }",
"}"));
// Source references heap, env changes local
assertSafeMoveVisibility(LINE_JOINER.join(
"var x = {};",
"function f(){",
" var y;",
" src: x.a;",
" env: y++;",
" dest: 3;",
"}"));
// Source changes heap, env refs local
assertSafeMoveVisibility(LINE_JOINER.join(
"var x = {};",
"function f(){",
" var y;",
" src: x.a++;",
" env: y;",
" dest: 3;",
"}"));
// MOD in function expressions shouldn't count
assertSafeMoveVisibility(LINE_JOINER.join(
"var x = {};",
"src: x.a;",
"env: (function() {",
" x.a++;",
"});",
"dest: 3;"));
// REF in function expressions shouldn't count
assertSafeMoveVisibility(LINE_JOINER.join(
"var x = {};",
"src: x.a++;",
"env: (function() {",
" x.a;",
"});",
"dest: 3;"));
}
public void testDegenerateUnsafeMoves() {
// Unsafe to move increment across read
assertUnsafeMoveDegenerate("src: x++; env: foo(y); dest: 3;");
// Unsafe to move read across increment
assertUnsafeMoveDegenerate("src: foo(y); env: x++; dest: 3;");
// Unsafe to move write across write
assertUnsafeMoveDegenerate("src: x = 7; env: y = 3; dest:3;");
}
public void testVisibilityUnsafeMoves() {
// Unsafe to move increment across read for global variables
assertUnsafeMoveVisibility("var x,y; src: x++; env: y; dest: 3;");
// Unsafe to move increment across read for local variables
assertUnsafeMoveVisibility(LINE_JOINER.join(
"function f() {",
" var x,y; src: x++; env: y; dest: 3;",
"}"));
// Unsafe to move increment across read for captured local variables
assertUnsafeMoveVisibility(LINE_JOINER.join(
"function f() {",
" var x,y; src: x++; env: y; dest: 3;",
" function inner() {",
" x; y;",
" }",
"}"));
// Unsafe to move increment across read for heap locations
assertUnsafeMoveVisibility("var x,y; src: x.a++; env: y.b; dest: 3;");
// Unsafe to move read across increment of for global variables
assertUnsafeMoveVisibility("var x,y; src: y; env: x++; dest: 3;");
// Unsafe to move read across increment for local variables
assertUnsafeMoveVisibility(LINE_JOINER.join(
"function f() {",
" var x,y; src: x; env: y++; dest: 3;",
"}"));
// Unsafe to move read across increment for captured local variables
assertUnsafeMoveVisibility(LINE_JOINER.join(
"function f() {",
" var x,y; src: x; env: y++; dest: 3;",
" function inner() {",
" x; y;",
" }",
"}"));
// Unsafe to move read across increment for heap locations
assertUnsafeMoveVisibility("var x,y; src: x.a; env: y.b++; dest: 3;");
// Unsafe to move write across write for globals
assertUnsafeMoveVisibility("var x,y; src: x = 7; env: y = 3; dest: 3;");
// Unsafe to move write across write for local variables
assertUnsafeMoveVisibility(LINE_JOINER.join(
"function f() {",
" var x,y; src: x = 7; env: y = 3; dest: 3;",
"}"));
// Unsafe to move write across write for captured local variables
assertUnsafeMoveVisibility(LINE_JOINER.join(
"function f() {",
" var x,y; src: x = 7; env: y = 3; dest: 3;",
" function inner() {",
" x; y;",
" }",
"}"));
// Unsafe to move write across write for heap locations
assertUnsafeMoveVisibility("var x,y; src: x.a = 7; env: y.b = 3; dest: 3;");
}
public void testVisibilityMoveCalls() {
// Interprocedural side effect analysis isn't implemented yet, so any calls
// should make movement unsafe, since we don't know what those calls are
// doing.
// TODO(dcc): implement interprocedural side effect analysis.
// Source makes call, env refs global
assertUnsafeMoveVisibility(LINE_JOINER.join(
"var x = {};",
"var g = function(){};",
"function f(){",
" var y;",
" src: g();",
" env: x;",
" dest: 3;",
"}"));
// Source makes refs global, env makes call
assertUnsafeMoveVisibility(LINE_JOINER.join(
"var x = {};",
"var g = function(){};",
"function f(){",
" var y;",
" src: x;",
" env: g();",
" dest: 3;",
"}"));
setAcceptedLanguage(LanguageMode.ECMASCRIPT_2015);
// Source makes a taggedTemplate Call.
assertUnsafeMoveVisibility(LINE_JOINER.join(
"function taggedTemplate(){};",
"function f(){",
" src: taggedTemplate`tTemplate`;",
" env: 24;",
" dest: 42;",
"}"));
// Env makes a taggedTemplate Call.
assertUnsafeMoveVisibility(LINE_JOINER.join(
"function taggedTemplate(){};",
"function f(){",
" src: 24;",
" env: taggedTemplate`tTemplate`;",
" dest: 42;",
"}"));
}
public void testVisibilityMergesParametersWithHeap() {
// For now, we expect the visibility based location abstraction
// to merge parameter variable locations with heap locations because
// parameters can be references and modified via the arguments object.
// Source changes heap, env refs parameter
assertUnsafeMoveVisibility(LINE_JOINER.join(
"var x = {};",
"function f(y){",
" src: x[0]++;",
" env: y;",
" dest: 3;",
"}"));
// Source refs heap, env changes parameters
assertUnsafeMoveVisibility(LINE_JOINER.join(
"var x = {};",
"function f(y){",
" src: x[0];",
" env: y++;",
" dest: 3;",
"}"));
// Source changes arguments explicitly, env refs parameter
assertUnsafeMoveVisibility(LINE_JOINER.join(
"var x = {};",
"function f(y){",
" src: arguments[0]++;",
" env: y;",
" dest: 3;",
"}"));
// Source refs arguments explicitly, env changes parameter
assertUnsafeMoveVisibility(LINE_JOINER.join(
"var x = {};",
"function f(y){",
" src: arguments[0];",
" env: y++;",
" dest: 3;",
"}"));
}
public void testMovedSideEffectsMustHaveSameControlFlow() {
// Safe to move within IF block
assertSafeMoveVisibility(LINE_JOINER.join(
"var a;",
"function f() {",
" var l;",
" if (l) {",
" src: a++;",
" env: 3;",
" dest: 3;",
" }",
"}"));
// Unsafe to move between two IF blocks
assertUnsafeMoveVisibility(LINE_JOINER.join(
"var a;",
"function f() {",
" var l;",
" if (l) {",
" src: a++;",
" env: 3;",
" }",
" if (l) {",
" dest: 3;",
" }",
"}"));
// Unsafe to move between then/else of same IF block
assertUnsafeMoveVisibility(LINE_JOINER.join(
"var a;",
"function f() {",
" var l;",
" if (l) {",
" src: a++;",
" env: 3;",
" } else {",
" dest: 3;",
" }",
"}"));
// Safe to move within WHILE block
assertSafeMoveVisibility(LINE_JOINER.join(
"var a;",
"function f() {",
" var l;",
" while (l) {",
" src: a++;",
" env: 3;",
" dest: 3;",
" }",
"}"));
// Unsafe to move within WHILE block with BREAK
assertUnsafeMoveVisibility(LINE_JOINER.join(
"var a;",
"function f() {",
" var l;",
" while (l) {",
" src: a++;",
" env: l;",
" break;",
" dest: 3;",
" }",
"}"));
// Unsafe to move within WHILE block with continue
assertUnsafeMoveVisibility(LINE_JOINER.join(
"var a;",
"function f() {",
" var l;",
" while (l) {",
" src: a++;",
" env: 3;",
" continue;",
" dest: 3;",
" }",
"}"));
// Unsafe to move within WHILE block with continue
assertUnsafeMoveVisibility(LINE_JOINER.join(
"var a;",
"function f() {",
" var l;",
" while (l) {",
" src: a++;",
" env: 3;",
" return;",
" dest: 3;",
" }",
"}"));
// Safe to move within DO
assertSafeMoveVisibility(LINE_JOINER.join(
"var a;",
"function f() {",
" var l;",
" do {",
" src: a++;",
" env: 3;",
" dest: 3;",
" } while(l)",
"}"));
// Unsafe to move outside DO
assertUnsafeMoveVisibility(LINE_JOINER.join(
"var a;",
"function f() {",
" var l;",
" do {",
" src: a++;",
" env: 3;",
" } while(l)",
" dest: 3;",
"}"));
// It should be safe to move within CASE
// but we disallow for now because analyzing
// CASE fall-through and BREAKs is complicated.
assertUnsafeMoveVisibility(LINE_JOINER.join(
"var a;",
"function f() {",
" var l;",
" switch(l) {",
" case 17:",
" src: a++;",
" env: 3;",
" dest: 3;",
" break;",
" }",
"}"));
// Unsafe to move between CASEs
assertUnsafeMoveVisibility(LINE_JOINER.join(
"var a;",
"function f() {",
" var l;",
" switch(l) {",
" case 17:",
" src: a++;",
" env: 3;",
" break;",
" case 18:",
" dest: 3;",
" break;",
" }",
"}"));
// Unsafe to move between FUNCTIONs
assertUnsafeMoveVisibility(LINE_JOINER.join(
"var a;",
"function f() {",
" src: a++;",
" env: 3;",
"}",
"function g() {",
" dest: 3;",
"}"));
}
private SideEffectsAnalysis.AbstractMotionEnvironment environment(
Node ...nodes) {
return new SideEffectsAnalysis.RawMotionEnvironment(
ImmutableSet.copyOf(nodes));
}
/**
* Asserts whether it is safe to move code labeled with {@code src} across
* an environment labeled {@code env} to another program point (immediately
* preceding code labeled {@code dest}).
*
* @param abstraction The type of location abstraction to use for analysis
* @param src The code snippet under test.
* @param expected The expected result of analysis
*/
private void assertMove(LocationAbstractionMode abstraction,
String src,
boolean expected) {
SideEffectsAnalysis analysis = compileAndRun(src, abstraction);
Node sourceNode = findLabeledStatement("src");
Node environmentNode = findLabeledStatement("env");
Node destinationNode = findLabeledStatement("dest");
boolean result = analysis.safeToMoveBefore(sourceNode,
environment(environmentNode), destinationNode);
if (expected) {
assertTrue(result);
} else {
assertFalse(result);
}
}
private void assertSafeMoveDegenerate(String src) {
assertMove(LocationAbstractionMode.DEGENERATE, src, true);
}
private void assertUnsafeMoveDegenerate(String src) {
assertMove(LocationAbstractionMode.DEGENERATE, src, false);
}
private void assertSafeMoveVisibility(String src) {
assertMove(LocationAbstractionMode.VISIBILITY_BASED, src, true);
}
private void assertUnsafeMoveVisibility(String src) {
assertMove(LocationAbstractionMode.VISIBILITY_BASED, src, false);
}
private SideEffectsAnalysis compileAndRun(String js,
LocationAbstractionMode locationAbstractionIdentifier) {
currentLocationAbstractionIdentifier = locationAbstractionIdentifier;
testSame(SHARED_EXTERNS, js, null);
currentJsRoot = getLastCompiler().jsRoot;
return currentAnalysis;
}
// Shamelessly stolen from NameReferenceGraphConstructionTest
private Node findLabeledStatement(String label) {
LabeledStatementSearcher s = new LabeledStatementSearcher(label);
NodeTraversal.traverseEs6(getLastCompiler(), getLastCompiler().jsRoot, s);
assertNotNull("Label " + label + " should be in the source code", s.found);
return s.found;
}
/**
* Quick traversal to find a given labeled statement in the AST.
*
* Given "foo", finds the statement a = x in
* foo: a = x;
*/
private static class LabeledStatementSearcher extends AbstractPostOrderCallback {
Node found = null;
final String target;
LabeledStatementSearcher(String target) {
this.target = target;
}
@Override
public void visit(NodeTraversal t, Node n, Node parent) {
if (n.isLabel() && target.equals(n.getFirstChild().getString())) {
found = n.getLastChild();
}
}
}
}