RFR: 8347830: [premain] UseCompatibleCompressedOops is broken after merging with mainline

[Vladimir Kozlov]

On Fri, 16 May 2025 02:33:45 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

> The issue was that we did not allocate space "noaccess prefix" before heap for read-only page when we setup type of encoding  with `UseCompatibleCompressedOops` flag. I update code which reserves heap for compressed oops to take into account this flag.
> 
> An other issue was that `UseCompatibleCompressedOops` flag was set during CDS arguments consistency checkup. But `UseCompressedOops` flag is set by GC ergonomics. I moved code to CDS ergonomics setting method.
> 
> During testing I hit assert that AOT code address table is missing some code blob address. But it was actually card table base address which pointed inside CodeCache. I added special case to check for it early.
> 
> Tested premain-tier1.

@ashu-mehra I refactored code as you asked.

@ashu-mehra I refactored code as you asked.

I looked on our old code where we added this flag and found that I missed 2 other places to check which I added now.

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PR Comment: https://git.openjdk.org/leyden/pull/67#issuecomment-2887372274
PR Comment: https://git.openjdk.org/leyden/pull/67#issuecomment-2887375237