On Wed, 28 Aug 2024 22:20:25 GMT, Shaojin Wen <[email protected]> wrote:
> A small optimization to reduce the code size of StackMapGenerator.Frame's
> pushStack and setLocalsFromArg methods
>
> Below is the compiler log of C2
>
>
> # baseline
> jdk.internal.classfile.impl.StackMapGenerator$Frame::pushStack (27 bytes)
> failed to inline: callee uses too much stack
> jdk.internal.classfile.impl.StackMapGenerator$Frame::pushStack (46 bytes)
> failed to inline: callee is too large
> jdk.internal.classfile.impl.StackMapGenerator$Frame::pushStack (183 bytes)
> failed to inline: callee is too large
> jdk.internal.classfile.impl.StackMapGenerator$Frame::setLocalsFromArg (367
> bytes) failed to inline: callee is too large
>
> # current
> jdk.internal.classfile.impl.StackMapGenerator$Frame::pushStack (26 bytes)
> inline
> jdk.internal.classfile.impl.StackMapGenerator$Frame::pushStack (37 bytes)
> failed to inline: callee is too large
> jdk.internal.classfile.impl.StackMapGenerator$Frame::pushStack (82 bytes)
> jdk.internal.classfile.impl.StackMapGenerator$Frame::setLocalsFromArg (255
> bytes) failed to inline: callee is too large
src/java.base/share/classes/jdk/internal/classfile/impl/StackMapGenerator.java
line 959:
> 957: : pushStack(
> 958: desc == CD_float ? Type.FLOAT_TYPE :
> 959: desc instanceof PrimitiveClassDescImpl ?
> Type.INTEGER_TYPE : Type.referenceType(desc));
I think you can first use a `desc.isPrimitive()` and then go through all
primitive type checks; handling references first should be faster in general.
src/java.base/share/classes/jdk/internal/classfile/impl/StackMapGenerator.java
line 1058:
> 1056: for (int i = 0; i < methodDesc.parameterCount(); i++) {
> 1057: var desc = methodDesc.parameterType(i);
> 1058: if (desc == CD_void) throw new AssertionError("Should
> not reach here");
You can use
Suggestion:
assert desc != CD_void;
So this fails in unit tests. But this takes code size.
src/java.base/share/classes/jdk/internal/classfile/impl/StackMapGenerator.java
line 1060:
> 1058: if (desc == CD_void) throw new AssertionError("Should
> not reach here");
> 1059: Type type;
> 1060: if (desc instanceof PrimitiveClassDescImpl) {
Can we use `desc.isPrimitive()`?
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/20756#discussion_r1735361672
PR Review Comment: https://git.openjdk.org/jdk/pull/20756#discussion_r1735362742
PR Review Comment: https://git.openjdk.org/jdk/pull/20756#discussion_r1735362061
