[vm] Fix Instructions::Equals for the JIT.

As discovered by @blaugold on GitHub, Instructions::Equals can give a
false negative on the JIT if the GC flags in the object header are set

This CL changes Instructions::Equals to only compare the
Instructions-specific portion of the object, namely the size_and_flags_
field and the content bytes. If those match, then the important parts of
the object header match: the cid is always kInstructionsCid, as the
Equals method assumes non-null instances, and the size in the object
header is calculated using the content size from size_and_flags_.

TEST=Manually ran failing tests after cherry picking CL 221360 on top.

Bug: https://github.com/dart-lang/sdk/issues/39843
Change-Id: I25c25bbe6b1bf615d4cd923bfe871da7e929822a
Cq-Include-Trybots: luci.dart.try:vm-kernel-precomp-dwarf-linux-product-x64-try,vm-kernel-precomp-linux-product-x64-try,vm-kernel-precomp-linux-release-x64-try,vm-kernel-linux-product-x64-try
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/221467
Commit-Queue: Tess Strickland <sstrickl@google.com>
Reviewed-by: Daco Harkes <dacoharkes@google.com>
1 file changed
tree: a0a198882c2c82daf19ecc645d8fe78fa94c2d9f
  1. .dart_tool/
  2. .github/
  3. benchmarks/
  4. build/
  5. client/
  6. docs/
  7. pkg/
  8. runtime/
  9. samples/
  10. samples-dev/
  11. samples_2/
  12. sdk/
  13. tests/
  14. third_party/
  15. tools/
  16. utils/
  17. .clang-format
  18. .gitattributes
  19. .gitconfig
  20. .gitignore
  21. .gn
  22. .mailmap
  23. .packages
  24. .style.yapf
  25. .vpython
  27. BUILD.gn
  28. CHANGELOG.md
  29. codereview.settings
  31. DEPS
  34. PRESUBMIT.py
  35. README.dart-sdk
  36. README.md
  37. sdk_args.gni
  38. SECURITY.md


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