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Avoid Names for descriptors, generic sigs, and string constants
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We can just keep these are short-lived Strings, rather than interning
them into the Name table for the entire lifetime of Global.
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@retronym
retronym committed Feb 27, 2019
1 parent 4a64e1f commit 688bf0f
Showing 1 changed file with 35 additions and 27 deletions.
62 changes: 35 additions & 27 deletions src/compiler/scala/tools/nsc/symtab/classfile/ClassfileParser.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -95,7 +95,7 @@ abstract class ClassfileParser {
private def readMethodFlags() = JavaAccFlags methodFlags u2
private def readFieldFlags() = JavaAccFlags fieldFlags u2
private def readTypeName() = readName().toTypeName
private def readName() = pool getName u2
private def readName() = pool.getName(u2).name
private def readType() = pool getType u2

private object unpickler extends scala.reflect.internal.pickling.UnPickler {
Expand Down Expand Up @@ -175,7 +175,7 @@ abstract class ClassfileParser {
protected val len = u2
protected val starts = new Array[Int](len)
protected val values = new Array[AnyRef](len)
protected val internalized = new Array[Name](len)
protected val internalized = new Array[NameOrString](len)

{ var i = 1
while (i < starts.length) {
Expand Down Expand Up @@ -206,28 +206,35 @@ abstract class ClassfileParser {
else this errorBadTag start
}

class NameOrString(val value: String) {
private var _name: Name = null
def name: Name = {
if (_name eq null) _name = TermName(value)
_name
}
}
/** Return the name found at given index. */
def getName(index: Int): Name = (
def getName(index: Int): NameOrString = (
if (index <= 0 || len <= index) errorBadIndex(index)
else values(index) match {
case name: Name => name
case name: NameOrString => name
case _ =>
val start = firstExpecting(index, CONSTANT_UTF8)
val len = in.getChar(start).toInt
recordAtIndex(TermName(fromMUTF8(in.buf, start, len + 2)), index)
recordAtIndex(new NameOrString(fromMUTF8(in.buf, start, len + 2)), index)
}
)

private def fromMUTF8(bytes: Array[Byte], offset: Int, len: Int): String =
new DataInputStream(new ByteArrayInputStream(bytes, offset, len)).readUTF

/** Return the name found at given index in the constant pool, with '/' replaced by '.'. */
def getExternalName(index: Int): Name = {
def getExternalName(index: Int): NameOrString = {
if (index <= 0 || len <= index)
errorBadIndex(index)

if (internalized(index) == null)
internalized(index) = getName(index).replace('/', '.')
internalized(index) = new NameOrString(getName(index).value.replace('/', '.'))

internalized(index)
}
Expand All @@ -237,7 +244,7 @@ abstract class ClassfileParser {
values(index) match {
case sym: Symbol => sym
case _ =>
val result = getClassName(index) match {
val result = getClassName(index).name match {
case name if nme.isModuleName(name) => rootMirror getModuleByName name.dropModule
case name => classNameToSymbol(name)
}
Expand All @@ -248,7 +255,7 @@ abstract class ClassfileParser {
/** Return the external name of the class info structure found at 'index'.
* Use 'getClassSymbol' if the class is sure to be a top-level class.
*/
def getClassName(index: Int): Name = {
def getClassName(index: Int): NameOrString = {
val start = firstExpecting(index, CONSTANT_CLASS)
getExternalName((in getChar start).toInt)
}
Expand All @@ -267,14 +274,14 @@ abstract class ClassfileParser {
val start = firstExpecting(index, CONSTANT_NAMEANDTYPE)
val name = getName(in.getChar(start).toInt)
// create a dummy symbol for method types
val dummy = ownerTpe.typeSymbol.newMethod(name.toTermName, ownerTpe.typeSymbol.pos)
val dummy = ownerTpe.typeSymbol.newMethod(name.name.toTermName, ownerTpe.typeSymbol.pos)
val tpe = getType(dummy, in.getChar(start + 2).toInt)
// fix the return type, which is blindly set to the class currently parsed
val restpe = tpe match {
case MethodType(formals, _) if name == nme.CONSTRUCTOR => MethodType(formals, ownerTpe)
case _ => tpe
case MethodType(formals, _) if name.name == nme.CONSTRUCTOR => MethodType(formals, ownerTpe)
case _ => tpe
}
((name, restpe))
((name.name, restpe))
}
}

Expand All @@ -289,21 +296,21 @@ abstract class ClassfileParser {
case cls: Symbol => cls.tpe_*
case _ =>
val name = getClassName(index)
name charAt 0 match {
case ARRAY_TAG => recordAtIndex(sigToType(null, name), index)
case _ => recordAtIndex(classNameToSymbol(name), index).tpe_*
name.value.charAt(0) match {
case ARRAY_TAG => recordAtIndex(sigToType(null, name.value), index)
case _ => recordAtIndex(classNameToSymbol(name.name), index).tpe_*
}
}
}

def getType(index: Int): Type = getType(null, index)
def getType(sym: Symbol, index: Int): Type = sigToType(sym, getExternalName(index))
def getType(sym: Symbol, index: Int): Type = sigToType(sym, getExternalName(index).value)
def getSuperClass(index: Int): Symbol = if (index == 0) AnyClass else getClassSymbol(index) // the only classfile that is allowed to have `0` in the super_class is java/lang/Object (see jvm spec)

private def createConstant(index: Int): Constant = {
val start = starts(index)
Constant((in.buf(start).toInt: @switch) match {
case CONSTANT_STRING => getName(in.getChar(start + 1).toInt).toString
case CONSTANT_STRING => getName(in.getChar(start + 1).toInt).value
case CONSTANT_INTEGER => in.getInt(start + 1)
case CONSTANT_FLOAT => in.getFloat(start + 1)
case CONSTANT_LONG => in.getLong(start + 1)
Expand Down Expand Up @@ -451,7 +458,7 @@ abstract class ClassfileParser {

val jflags = readClassFlags()
val classNameIndex = u2
currentClass = pool.getClassName(classNameIndex)
currentClass = pool.getClassName(classNameIndex).name

// Ensure that (top-level) classfiles are in the correct directory
val isTopLevel = !(currentClass containsChar '$') // Java class name; *don't* try to to use Scala name decoding (scala/bug#7532)
Expand Down Expand Up @@ -650,7 +657,8 @@ abstract class ClassfileParser {
}
}

private def sigToType(sym: Symbol, sig: Name): Type = {
private def sigToType(sym: Symbol, sig: String): Type = {
val sigChars = sig.toCharArray
var index = 0
val end = sig.length
def accept(ch: Char): Unit = {
Expand All @@ -660,7 +668,7 @@ abstract class ClassfileParser {
def subName(isDelimiter: Char => Boolean): Name = {
val start = index
while (!isDelimiter(sig.charAt(index))) { index += 1 }
sig.subName(start, index)
newTermName(sigChars, start, index - start)
}
def sig2type(tparams: immutable.Map[Name,Symbol], skiptvs: Boolean): Type = {
val tag = sig.charAt(index); index += 1
Expand Down Expand Up @@ -842,7 +850,7 @@ abstract class ClassfileParser {
attrName match {
case tpnme.SignatureATTR =>
val sig = pool.getExternalName(u2)
val newType = sigToType(sym, sig)
val newType = sigToType(sym, sig.value)
sym.setInfo(newType)

case tpnme.SyntheticATTR =>
Expand Down Expand Up @@ -879,7 +887,7 @@ abstract class ClassfileParser {
val access = u2

val name =
if ((access & ACC_SYNTHETIC) == 0) rawname.encode
if ((access & ACC_SYNTHETIC) == 0) rawname.name.encode
else nme.NO_NAME

paramNames += name
Expand Down Expand Up @@ -985,7 +993,7 @@ abstract class ClassfileParser {
val index = u2
tag match {
case STRING_TAG =>
Some(LiteralAnnotArg(Constant(pool.getName(index).toString)))
Some(LiteralAnnotArg(Constant(pool.getName(index).value)))
case BOOL_TAG | BYTE_TAG | CHAR_TAG | SHORT_TAG | INT_TAG |
LONG_TAG | FLOAT_TAG | DOUBLE_TAG =>
Some(LiteralAnnotArg(pool.getConstant(index)))
Expand Down Expand Up @@ -1259,9 +1267,9 @@ abstract class ClassfileParser {

/** An entry in the InnerClasses attribute of this class file. */
case class InnerClassEntry(external: Int, outer: Int, name: Int, jflags: JavaAccFlags) {
def externalName = pool getClassName external
def outerName = pool getClassName outer
def originalName = pool getName name
def externalName = pool.getClassName(external).name
def outerName = pool.getClassName(outer).name
def originalName = pool.getName(name).name
def isModule = originalName.isTermName
def scope = if (jflags.isStatic) staticScope else instanceScope
def enclosing = if (jflags.isStatic) enclModule else enclClass
Expand Down

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