RFR: 8341136: Optimize StackMapGenerator::trimAndCompress

[Abdelhak Zaaim]

On Fri, 27 Sep 2024 17:05:25 GMT, Shaojin Wen <swen at openjdk.org> wrote:

> A small optimization to reduce the write operations of trimAndCompress

We can improve performance by avoiding repeated array access in the loop. Instead of accessing types[i] multiple times, we cache it in a local variable. Here's the optimized version
`for (int i = 0; i < count; i++) {
    Type current = types[i]; 
    if (!current.isCategory2_2nd()) {
        if (compressed != i) {
            types[compressed] = current;
        }
        compressed++;
    }
}
` This reduces overhead from multiple array lookups.

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Changes requested by abdelhak-zaaim at github.com (no known OpenJDK username).

PR Review: https://git.openjdk.org/jdk/pull/21227#pullrequestreview-2335379912