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Bug 718531 - Fix functions with try-finally to not return wrong value in some cases. r=shu

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This commit is contained in:
Jan de Mooij 2015-02-19 13:19:03 +01:00
parent e2ea97f6bc
commit 13fb9a89bc
3 changed files with 87 additions and 24 deletions
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64
js/src/frontend/BytecodeEmitter.cpp
View File

@ -143,6 +143,7 @@ BytecodeEmitter::BytecodeEmitter(BytecodeEmitter *parent,
yieldOffsetList(sc->context),
typesetCount(0),
hasSingletons(false),
hasTryFinally(false),
emittingForInit(false),
emittingRunOnceLambda(false),
insideEval(insideEval),
@ -3120,37 +3121,51 @@ frontend::EmitFunctionScript(ExclusiveContext *cx, BytecodeEmitter *bce, ParseNo
if (!EmitTree(cx, bce, body))
return false;
// If we fall off the end of a generator, do a final yield.
if (bce->sc->isFunctionBox() && bce->sc->asFunctionBox()->isGenerator()) {
if (bce->sc->asFunctionBox()->isStarGenerator() && !EmitPrepareIteratorResult(cx, bce))
return false;
if (bce->sc->isFunctionBox()) {
if (bce->sc->asFunctionBox()->isGenerator()) {
// If we fall off the end of a generator, do a final yield.
if (bce->sc->asFunctionBox()->isStarGenerator() && !EmitPrepareIteratorResult(cx, bce))
return false;
if (Emit1(cx, bce, JSOP_UNDEFINED) < 0)
return false;
if (Emit1(cx, bce, JSOP_UNDEFINED) < 0)
return false;
if (bce->sc->asFunctionBox()->isStarGenerator() && !EmitFinishIteratorResult(cx, bce, true))
return false;
if (bce->sc->asFunctionBox()->isStarGenerator() &&
!EmitFinishIteratorResult(cx, bce, true))
{
return false;
}
if (Emit1(cx, bce, JSOP_SETRVAL) < 0)
return false;
if (Emit1(cx, bce, JSOP_SETRVAL) < 0)
return false;
ScopeCoordinate sc;
// We know that .generator is on the top scope chain node, as we are
// at the function end.
sc.setHops(0);
MOZ_ALWAYS_TRUE(LookupAliasedNameSlot(bce, bce->script, cx->names().dotGenerator, &sc));
if (!EmitAliasedVarOp(cx, JSOP_GETALIASEDVAR, sc, DontCheckLexical, bce))
return false;
ScopeCoordinate sc;
// We know that .generator is on the top scope chain node, as we are
// at the function end.
sc.setHops(0);
MOZ_ALWAYS_TRUE(LookupAliasedNameSlot(bce, bce->script, cx->names().dotGenerator, &sc));
if (!EmitAliasedVarOp(cx, JSOP_GETALIASEDVAR, sc, DontCheckLexical, bce))
return false;
// No need to check for finally blocks, etc as in EmitReturn.
if (!EmitYieldOp(cx, bce, JSOP_FINALYIELDRVAL))
return false;
// No need to check for finally blocks, etc as in EmitReturn.
if (!EmitYieldOp(cx, bce, JSOP_FINALYIELDRVAL))
return false;
} else {
// Non-generator functions just return |undefined|. The JSOP_RETRVAL
// emitted below will do that, except if the script has a finally
// block: there can be a non-undefined value in the return value
// slot. We just emit an explicit return in this case.
if (bce->hasTryFinally) {
if (Emit1(cx, bce, JSOP_UNDEFINED) < 0)
return false;
if (Emit1(cx, bce, JSOP_RETURN) < 0)
return false;
}
}
}
/*
* Always end the script with a JSOP_RETRVAL. Some other parts of the codebase
* depend on this opcode, e.g. js_InternalInterpret.
*/
// Always end the script with a JSOP_RETRVAL. Some other parts of the codebase
// depend on this opcode, e.g. InterpreterRegs::setToEndOfScript.
if (Emit1(cx, bce, JSOP_RETRVAL) < 0)
return false;
@ -4658,6 +4673,7 @@ EmitTry(ExclusiveContext *cx, BytecodeEmitter *bce, ParseNode *pn)
{
return false;
}
bce->hasTryFinally = true;
MOZ_ASSERT(bce->stackDepth == depth);
}
if (!PopStatementBCE(cx, bce))

2
js/src/frontend/BytecodeEmitter.h
View File

@ -162,6 +162,8 @@ struct BytecodeEmitter
bool hasSingletons:1; /* script contains singleton initializer JSOP_OBJECT */
bool hasTryFinally:1; /* script contains finally block */
bool emittingForInit:1; /* true while emitting init expr of for; exclude 'in' */
bool emittingRunOnceLambda:1; /* true while emitting a lambda which is only

45
js/src/jit-test/tests/basic/finally-implicit-return.js Normal file
View File

@ -0,0 +1,45 @@
// Implicit return at the end of a function should return |undefined|,
// even if we initially set another return value and then executed a finally
// block.
function test1() {
try {
try {
return 3;
} finally {
throw 4;
}
} catch (e) {}
}
assertEq(test1(), undefined);
function test2() {
L: try {
return 3;
} finally {
break L;
}
}
assertEq(test2(), undefined);
function test3() {
for (var i=0; i<2; i++) {
try {
return 5;
} finally {
continue;
}
}
}
assertEq(test3(), undefined);
// "return;" should work the same way.
function test4() {
L: try {
return 6;
} finally {
break L;
}
return;
}
assertEq(test4(), undefined);