archive/jdk
1
0
Fork 0
mirror of https://github.com/openjdk/jdk.git synced 2025-08-26 14:24:46 +02:00
Code Issues Projects Releases Packages Wiki Activity Actions

8342458: More consistent constant instruction handling

Browse source 
Reviewed-by: asotona
This commit is contained in:
Chen Liang 2024-10-31 14:01:13 +00:00
parent 29ae26517f
commit 3ccd2f757d
3 changed files with 147 additions and 77 deletions
Download patch file Download diff file Expand all files Collapse all files

10
src/java.base/share/classes/jdk/internal/classfile/impl/AbstractInstruction.java
View file

@ -673,7 +673,8 @@ public abstract sealed class AbstractInstruction
if (writer.canWriteDirect(code.constantPool()))
super.writeTo(writer);
else
writer.writeLoadConstant(op, constantEntry());
// We have writer.canWriteDirect(constantEntry().constantPool()) == false
writer.writeAdaptLoadConstant(op, constantEntry());
}
@Override
@ -1346,7 +1347,12 @@ public abstract sealed class AbstractInstruction
@Override
public void writeTo(DirectCodeBuilder writer) {
writer.writeLoadConstant(op, constant);
var constant = this.constant;
if (writer.canWriteDirect(constant.constantPool()))
// Allows writing ldc_w small index constants upon user request
writer.writeDirectLoadConstant(op, constant);
else
writer.writeAdaptLoadConstant(op, constant);
}
@Override

27
src/java.base/share/classes/jdk/internal/classfile/impl/DirectCodeBuilder.java
View file

@ -670,16 +670,22 @@ public final class DirectCodeBuilder
}
}
public void writeLoadConstant(Opcode opcode, LoadableConstantEntry value) {
// Make sure Long and Double have LDC2_W and
// rewrite to _W if index is >= 256
int index = AbstractPoolEntry.maybeClone(constantPool, value).index();
if (value instanceof LongEntry || value instanceof DoubleEntry) {
opcode = Opcode.LDC2_W;
} else if (index >= 256)
opcode = Opcode.LDC_W;
// value may not be writable to this constant pool
public void writeAdaptLoadConstant(Opcode opcode, LoadableConstantEntry value) {
var pe = AbstractPoolEntry.maybeClone(constantPool, value);
int index = pe.index();
if (pe != value && opcode != Opcode.LDC2_W) {
// rewrite ldc/ldc_w if external entry; ldc2_w never needs rewrites
opcode = index <= 0xFF ? Opcode.LDC : Opcode.LDC_W;
}
assert !opcode.isWide();
writeDirectLoadConstant(opcode, pe);
}
// the loadable entry is writable to this constant pool
public void writeDirectLoadConstant(Opcode opcode, LoadableConstantEntry pe) {
assert !opcode.isWide() && canWriteDirect(pe.constantPool());
int index = pe.index();
if (opcode.sizeIfFixed() == 3) {
bytecodesBufWriter.writeU1U2(opcode.bytecode(), index);
} else {
@ -1654,7 +1660,8 @@ public final class DirectCodeBuilder
@Override
public CodeBuilder ldc(LoadableConstantEntry entry) {
writeLoadConstant(BytecodeHelpers.ldcOpcode(entry), entry);
var direct = AbstractPoolEntry.maybeClone(constantPool, entry);
writeDirectLoadConstant(BytecodeHelpers.ldcOpcode(direct), direct);
return this;
}