[11u] RFR: backport of JDK-8208658: Make CDS archived heap regions usable even if compressed oop encoding has changed

[Langer, Christoph]

Hi Jiangli,

This backport looks good to me.

Would you want me to run it through our test infrastructure to get additional confidence?

Cheers
Christoph

> -----Original Message-----
> From: hotspot-runtime-dev <hotspot-runtime-dev-
> bounces at openjdk.java.net> On Behalf Of Jiangli Zhou
> Sent: Mittwoch, 22. Januar 2020 02:05
> To: jdk-updates-dev at openjdk.java.net; hotspot-runtime-dev <hotspot-
> runtime-dev at openjdk.java.net>
> Subject: [11u] RFR: backport of JDK-8208658: Make CDS archived heap
> regions usable even if compressed oop encoding has changed
> 
> I'd like to request a backport of JDK-8208658 to JDK 11u. It was an
> enhancement that improves CDS usability and would improve startup time
> if there's an existing default CDS archive (currently does not exist
> in OpenJDK 11).
> 
>   webrev: http://cr.openjdk.java.net/~jiangli/8208658-backport/webrev.00
> 
> The backport applied to jdk11u-dev mostly clean. The following small
> set of changes were hand merged to filemap.cpp without additional
> modifications. The backport was tested with all existing cds and
> appcds tests, and tier 1 tests.
> 
> --- filemap.cpp
> +++ filemap.cpp
> @@ -967,7 +1069,9 @@
>      if (base == NULL || base != addr) {
>        // dealloc the regions from java heap
>        dealloc_archive_heap_regions(regions, region_num);
> -      log_info(cds)("UseSharedSpaces: Unable to map at required
> address in java heap.");
> +      log_info(cds)("UseSharedSpaces: Unable to map at required
> address in java heap. "
> +                    INTPTR_FORMAT ", size = " SIZE_FORMAT " bytes",
> +                    p2i(addr), regions[i].byte_size());
>        return false;
>      }
>    }
> @@ -1216,34 +1348,25 @@
>           idx == MetaspaceShared::rw ||
>           idx == MetaspaceShared::mc ||
>           idx == MetaspaceShared::md, "invalid region index");
> -  char* base = _header->region_addr(idx);
> +  char* base = region_addr(idx);
>    if (p >= base && p < base + space_at(idx)->_used) {
>      return true;
>    }
>    return false;
>  }
> 
> -void FileMapInfo::print_shared_spaces() {
> -  tty->print_cr("Shared Spaces:");
> -  for (int i = 0; i < MetaspaceShared::n_regions; i++) {
> -    CDSFileMapRegion* si = space_at(i);
> -    char *base = _header->region_addr(i);
> -    tty->print("  %s " INTPTR_FORMAT "-" INTPTR_FORMAT,
> -                        shared_region_name[i],
> -                        p2i(base), p2i(base + si->_used));
> -  }
> -}
> -
>  // Unmap mapped regions of shared space.
>  void FileMapInfo::stop_sharing_and_unmap(const char* msg) {
>    FileMapInfo *map_info = FileMapInfo::current_info();
>    if (map_info) {
>      map_info->fail_continue("%s", msg);
>      for (int i = 0; i < MetaspaceShared::num_non_heap_spaces; i++) {
> -      char *addr = map_info->_header->region_addr(i);
> -      if (addr != NULL && !MetaspaceShared::is_heap_region(i)) {
> -        map_info->unmap_region(i);
> -        map_info->space_at(i)->_addr._base = NULL;
> +      if (!MetaspaceShared::is_heap_region(i)) {
> +        char *addr = map_info->region_addr(i);
> +        if (addr != NULL) {
> +          map_info->unmap_region(i);
> +          map_info->space_at(i)->_addr._base = NULL;
> +        }
> 
> Best regards,
> Jiangli