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Devirtualize duplicate methods
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Closes #2041

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=134430055
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@blickly
Nick Santos authored and blickly committed Sep 28, 2016
1 parent 0a01f84 commit cc3cc90
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Showing 2 changed files with 88 additions and 57 deletions.
30 changes: 28 additions & 2 deletions src/com/google/javascript/jscomp/DevirtualizePrototypeMethods.java
View file
Expand Up @@ -22,7 +22,6 @@
import com.google.javascript.rhino.IR;
import com.google.javascript.rhino.Node;
import com.google.javascript.rhino.TypeI;

import java.util.Collection;

/**
Expand Down Expand Up @@ -87,6 +86,9 @@ public void process(
private static boolean isCall(UseSite site) {
Node node = site.node;
Node parent = node.getParent();
if (parent == null) {
return false;
}
return (parent.getFirstChild() == node) && parent.isCall();
}

Expand Down Expand Up @@ -275,7 +277,7 @@ private boolean isEligibleDefinition(DefinitionUseSiteFinder defFinder,
// Multiple definitions prevent rewrite.
Collection<Definition> singleSiteDefinitions =
defFinder.getDefinitionsReferencedAt(nameNode);
if (singleSiteDefinitions.size() > 1) {
if (!allDefinitionsEquivalent(singleSiteDefinitions)) {
return false;
}
Preconditions.checkState(!singleSiteDefinitions.isEmpty());
Expand All @@ -295,6 +297,30 @@ private boolean isEligibleDefinition(DefinitionUseSiteFinder defFinder,
return true;
}

/** Given a set of method definitions, verify they are the same. */
boolean allDefinitionsEquivalent(Collection<Definition> definitions) {
if (definitions.size() <= 1) {
return true;
}

Definition first = null;
for (Definition definition : definitions) {
if (definition.getRValue() == null) {
return false; // We can't tell if they're all the same.
}

if (first == null) {
first = definition;
continue;
}

if (!compiler.areNodesEqualForInlining(first.getRValue(), definition.getRValue())) {
return false;
}
}
return true;
}

/**
* Rewrites object method call sites as calls to global functions
* that take "this" as their first argument.
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115 changes: 60 additions & 55 deletions test/com/google/javascript/jscomp/DevirtualizePrototypeMethodsTest.java
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Expand Up @@ -22,7 +22,6 @@
import com.google.javascript.rhino.Node;
import com.google.javascript.rhino.Token;
import com.google.javascript.rhino.jstype.JSType;

import java.util.ArrayList;
import java.util.List;

Expand Down Expand Up @@ -232,79 +231,85 @@ public void testNoRewriteNamespaceFunctions() throws Exception {
testSame(source);
}

/**
* Inputs for multiple definition tests.
*/
private static class NoRewriteMultipleDefinitionTestInput {
static final String TEMPLATE = ".prototype.foo = function() {}";
static final String SOURCE_A = "a" + TEMPLATE;
static final String SOURCE_B = "b" + TEMPLATE;
static final String CALL = "o.foo()";

static final String SINGLE_DEFINITION_EXPECTED =
"var JSCompiler_StaticMethods_foo = " +
" function(JSCompiler_StaticMethods_foo$self) {};" +
"JSCompiler_StaticMethods_foo(o)";

private NoRewriteMultipleDefinitionTestInput() {}
}

public void testRewriteSingleDefinition1() throws Exception {
test(semicolonJoin(NoRewriteMultipleDefinitionTestInput.SOURCE_A,
NoRewriteMultipleDefinitionTestInput.CALL),
NoRewriteMultipleDefinitionTestInput.SINGLE_DEFINITION_EXPECTED);
}

public void testRewriteSingleDefinition2() throws Exception {
test(semicolonJoin(NoRewriteMultipleDefinitionTestInput.SOURCE_B,
NoRewriteMultipleDefinitionTestInput.CALL),
NoRewriteMultipleDefinitionTestInput.SINGLE_DEFINITION_EXPECTED);
}

public void testNoRewriteMultipleDefinition1() throws Exception {
testSame(semicolonJoin(NoRewriteMultipleDefinitionTestInput.SOURCE_A,
NoRewriteMultipleDefinitionTestInput.SOURCE_A,
NoRewriteMultipleDefinitionTestInput.CALL));
public void testRewriteIfDuplicates() throws Exception {
test(
LINE_JOINER.join(
"function A(){}; A.prototype.getFoo = function() { return 1; }; ",
"function B(){}; B.prototype.getFoo = function() { return 1; }; ",
"var x = Math.random() ? new A() : new B();",
"alert(x.getFoo());"),
LINE_JOINER.join(
"function A(){}; ",
"var JSCompiler_StaticMethods_getFoo=",
"function(JSCompiler_StaticMethods_getFoo$self){return 1};",
"function B(){};",
"B.prototype.getFoo=function(){return 1};",
"var x = Math.random() ? new A() : new B();",
"alert(JSCompiler_StaticMethods_getFoo(x));"));
}

public void testNoRewriteMultipleDefinition2() throws Exception {
testSame(semicolonJoin(NoRewriteMultipleDefinitionTestInput.SOURCE_B,
NoRewriteMultipleDefinitionTestInput.SOURCE_B,
NoRewriteMultipleDefinitionTestInput.CALL));
public void testRewriteIfDuplicatesWithThis() throws Exception {
test(
LINE_JOINER.join(
"function A(){}; A.prototype.getFoo = ",
"function() { return this._foo + 1; }; ",
"function B(){}; B.prototype.getFoo = ",
"function() { return this._foo + 1; }; ",
"var x = Math.random() ? new A() : new B();",
"alert(x.getFoo());"),
LINE_JOINER.join(
"function A(){}; ",
"var JSCompiler_StaticMethods_getFoo=",
"function(JSCompiler_StaticMethods_getFoo$self){",
" return JSCompiler_StaticMethods_getFoo$self._foo + 1",
"};",
"function B(){};",
"B.prototype.getFoo=function(){return this._foo + 1};",
"var x = Math.random() ? new A() : new B();",
"alert(JSCompiler_StaticMethods_getFoo(x));"));
}

public void testNoRewriteMultipleDefinition3() throws Exception {
testSame(semicolonJoin(NoRewriteMultipleDefinitionTestInput.SOURCE_A,
NoRewriteMultipleDefinitionTestInput.SOURCE_B,
NoRewriteMultipleDefinitionTestInput.CALL));
public void testNoRewriteIfDuplicates() throws Exception {
testSame(
LINE_JOINER.join(
"function A(){}; A.prototype.getFoo = function() { return 1; }; ",
"function B(){}; B.prototype.getFoo = function() { return 2; }; ",
"var x = Math.random() ? new A() : new B();",
"alert(x.getFoo());"));
}

/**
* Inputs for object literal tests.
*/
private static class NoRewritePrototypeObjectLiteralsTestInput {
static final String REGULAR = "b.prototype.foo = function() {}";
static final String OBJ_LIT = "a.prototype = {foo : function() {}}";
static final String REGULAR = "b.prototype.foo = function() { return 1; }";
static final String OBJ_LIT = "a.prototype = {foo : function() { return 2; }}";
static final String CALL = "o.foo()";

private NoRewritePrototypeObjectLiteralsTestInput() {}
}

public void testRewritePrototypeNoObjectLiterals() throws Exception {
test(semicolonJoin(NoRewritePrototypeObjectLiteralsTestInput.REGULAR,
NoRewritePrototypeObjectLiteralsTestInput.CALL),
"var JSCompiler_StaticMethods_foo = " +
"function(JSCompiler_StaticMethods_foo$self) {};" +
"JSCompiler_StaticMethods_foo(o)");
test(
semicolonJoin(
NoRewritePrototypeObjectLiteralsTestInput.REGULAR,
NoRewritePrototypeObjectLiteralsTestInput.CALL),
LINE_JOINER.join(
"var JSCompiler_StaticMethods_foo = ",
"function(JSCompiler_StaticMethods_foo$self) { return 1; };",
"JSCompiler_StaticMethods_foo(o)"));
}

public void testRewritePrototypeObjectLiterals1() throws Exception {
test(semicolonJoin(NoRewritePrototypeObjectLiteralsTestInput.OBJ_LIT,
NoRewritePrototypeObjectLiteralsTestInput.CALL),
"a.prototype={};" +
"var JSCompiler_StaticMethods_foo=" +
"function(JSCompiler_StaticMethods_foo$self){};" +
"JSCompiler_StaticMethods_foo(o)");
test(
semicolonJoin(
NoRewritePrototypeObjectLiteralsTestInput.OBJ_LIT,
NoRewritePrototypeObjectLiteralsTestInput.CALL),
LINE_JOINER.join(
"a.prototype={};",
"var JSCompiler_StaticMethods_foo=",
"function(JSCompiler_StaticMethods_foo$self){ return 2; };",
"JSCompiler_StaticMethods_foo(o)"));
}

public void testNoRewritePrototypeObjectLiterals2() throws Exception {
Expand Down

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