[ci skip] UPGRADING

Author: arnaud-lb

UPGRADING.INTERNALS

@@ -16,6 +16,10 @@ PHP 8.3 INTERNALS UPGRADE NOTES
 
 * zend_class_entry now possesses a default_object_handlers field, which
   provides a default object handler when create_object() is not overriding it.
+* Custom Fiber implementations have to initialize EG(stack_limit) and
+  EG(stack_base).
+* EG(opline_before_exception) may now be null if the VM throws an exception
+  before executing any opline.
 
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 2. Build system changes
@@ -28,10 +32,14 @@ PHP 8.3 INTERNALS UPGRADE NOTES
  a. ext/json
    - A new function php_json_validate_ex has been added to check if the
      provided C string is valid for the given depth and options.
+
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 4. OpCode changes
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 5. SAPI changes
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+
+* SAPIs that may execute in alternative stacks have to set EG(stack_limit) and
+  EG(stack_base)