exceptionHandlerTable.hpp

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#ifndef SHARE_CODE_EXCEPTIONHANDLERTABLE_HPP
#defineSHARE_CODE_EXCEPTIONHANDLERTABLE_HPP

#include"memory/allocation.hpp"
#include"oops/method.hpp"
#include"utilities/align.hpp"

// A HandlerTableEntry describes an individual entry of a subtable
// of ExceptionHandlerTable. An entry consists of a pair(bci, pco),
// where bci is the exception handler bci, and pco is the pc offset
// relative to the nmethod code start for the compiled exception
// handler corresponding to the (interpreted) exception handler
// starting at bci.
//
// The first HandlerTableEntry of each subtable holds the length
// and catch_pco for the subtable (the length is the number of
// subtable entries w/o header).

classHandlerTableEntry {
private:
int _bci;
int _pco;
int _scope_depth;

public:
HandlerTableEntry(int bci, int pco, int scope_depth) {
assert( 0 <= pco, "pco must be positive");
assert( 0 <= scope_depth, "scope_depth must be positive");
 _bci = bci;
 _pco = pco;
 _scope_depth = scope_depth;
 }

intlen() const { return _bci; } // for entry at subtable begin
intbci() const { return _bci; }
intpco() const { return _pco; }
intscope_depth() const { return _scope_depth; }
};


// An ExceptionHandlerTable is an abstraction over a list of subtables
// of exception handlers for CatchNodes. Each subtable has a one-entry
// header holding length and catch_pco of the subtable, followed
// by 'length' entries for each exception handler that can be reached
// from the corresponding CatchNode. The catch_pco is the pc offset of
// the CatchNode in the corresponding nmethod. Empty subtables are dis-
// carded.
//
// Structure of the table:
//
// table = { subtable }.
// subtable = header entry { entry }.
// header = a pair (number of subtable entries, catch pc offset, [unused])
// entry = a pair (handler bci, handler pc offset, scope depth)
//
// An ExceptionHandlerTable can be created from scratch, in which case
// it is possible to add subtables. It can also be created from an
// nmethod (for lookup purposes) in which case the table cannot be
// modified.

classnmethod;
classExceptionHandlerTable {
private:
 HandlerTableEntry* _table; // the table
int _length; // the current length of the table
int _size; // the number of allocated entries
 ReallocMark _nesting; // assertion check for reallocations

public:
// add the entry & grow the table if needed
voidadd_entry(HandlerTableEntry entry);
 HandlerTableEntry* subtable_for(int catch_pco) const;

// (compile-time) construction within compiler
ExceptionHandlerTable(int initial_size = 8);

// (run-time) construction from nmethod
ExceptionHandlerTable(const nmethod* nm);

// (compile-time) add entries
voidadd_subtable(
int catch_pco, // the pc offset for the CatchNode
 GrowableArray<intptr_t>* handler_bcis, // the exception handler entry point bcis
 GrowableArray<intptr_t>* scope_depths_from_top_scope,
// if representing exception handlers in multiple
// inlined scopes, indicates which scope relative to
// the youngest/innermost one in which we are performing
// the lookup; zero (or null GrowableArray) indicates
// innermost scope
 GrowableArray<intptr_t>* handler_pcos // pc offsets for the compiled handlers
 );

// nmethod support
intsize_in_bytes() const { returnalign_up(_length * (int)sizeof(HandlerTableEntry), oopSize); }
voidcopy_to(nmethod* nm);
voidcopy_bytes_to(address addr);

// lookup
 HandlerTableEntry* entry_for(int catch_pco, int handler_bci, int scope_depth) const;

// debugging
voidprint_subtable(HandlerTableEntry* t, address base = nullptr) const;
voidprint(address base = nullptr) const;
voidprint_subtable_for(int catch_pco) const;
};


// ----------------------------------------------------------------------------
// Implicit null exception tables. Maps an exception PC offset to a
// continuation PC offset. During construction it's a variable sized
// array with a max size and current length. When stored inside an
// nmethod a zero length table takes no space. This is detected by
// nul_chk_table_size() == 0. Otherwise the table has a length word
// followed by pairs of <excp-offset, const-offset>.

// Use 32-bit representation for offsets
typedefuint implicit_null_entry;

classImplicitExceptionTable {
uint _size;
uint _len;
 implicit_null_entry *_data;
 implicit_null_entry *adr( uint idx ) const { return &_data[2*idx]; }
 ReallocMark _nesting; // assertion check for reallocations

public:
ImplicitExceptionTable( ) : _size(0), _len(0), _data(nullptr) { }
// (run-time) construction from nmethod
ImplicitExceptionTable(const nmethod *nm);

voidset_size( uint size );
voidappend( uint exec_off, uint cont_off );

#if INCLUDE_JVMCI
voidadd_deoptimize(uint exec_off) {
// Use the same offset as a marker value for deoptimization
append(exec_off, exec_off);
 }
#endif

// Returns the offset to continue execution at. If the returned
// value equals exec_off then the dispatch is expected to be a
// deoptimization instead.
uintcontinuation_offset( uint exec_off ) const;

uintlen() const { return _len; }

uintget_exec_offset(uint i) { assert(i < _len, "oob"); return *adr(i); }
uintget_cont_offset(uint i) { assert(i < _len, "oob"); return *(adr(i) + 1); }

intsize_in_bytes() const { returnlen() == 0 ? 0 : ((2 * len() + 1) * (int)sizeof(implicit_null_entry)); }

voidcopy_to(nmethod* nm);
voidcopy_bytes_to(address addr, int size);
voidprint(address base) const;
voidverify(nmethod *nm) const;
};

#endif// SHARE_CODE_EXCEPTIONHANDLERTABLE_HPP