RFR: 8340708: Optimize StackMapGenerator::processMethod

[Chen Liang]

On Mon, 23 Sep 2024 13:53:13 GMT, Shaojin Wen <swen at openjdk.org> wrote:

> A small optimization of processMethod, by using local variables and extracting exception methods, reduces codeSize from 326 to 286

src/java.base/share/classes/jdk/internal/classfile/impl/StackMapGenerator.java line 432:

> 430:                     nextFrame.dirty = false;
> 431:                 } else if (thisOffset < bcs.bci()) {
> 432:                     throw new ClassFormatError(String.format("Bad stack map offset %d", thisOffset));

@asotona Is this CFE an outdated implementation behavior from an older implementation? If yes, we can just use `generatorError("Bad stack map offset");` instead.

src/java.base/share/classes/jdk/internal/classfile/impl/StackMapGenerator.java line 444:

> 442: 
> 443:     private static ClassFormatError classFormatError(int thisOffset) {
> 444:         throw new ClassFormatError(String.format("Bad stack map offset %d", thisOffset));

Suggestion:

        return new ClassFormatError(String.format("Bad stack map offset %d", thisOffset));

Prefer to return instead of throw in such convenience methods.

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PR Review Comment: https://git.openjdk.org/jdk/pull/21137#discussion_r1771672919
PR Review Comment: https://git.openjdk.org/jdk/pull/21137#discussion_r1771673590