Java local variable table processing. More...

#include "java_bytecode_convert_method_class.h"
#include <util/arith_tools.h>
#include <util/invariant.h>
#include <util/string2int.h>
#include <util/symbol_table_base.h>
#include "java_types.h"
#include <iostream>

Include dependency graph for java_local_variable_table.cpp:

Go to the source code of this file.

Classes
struct	procedure_local_cfg_baset< T, java_bytecode_convert_methodt::method_with_amapt, java_bytecode_convert_methodt::method_offsett >

struct	is_predecessor_oft

Typedefs
typedef java_bytecode_convert_methodt::holet	holet

typedef java_bytecode_convert_methodt::local_variable_with_holest	local_variable_with_holest

typedef java_bytecode_convert_methodt::local_variable_table_with_holest	local_variable_table_with_holest

typedef java_bytecode_convert_methodt::address_mapt	address_mapt

typedef java_bytecode_convert_methodt::java_cfg_dominatorst	java_cfg_dominatorst

typedef std::map< local_variable_with_holest , std::set< local_variable_with_holest > >	predecessor_mapt

Functions
static bool	lt_index (const local_variable_with_holest &a, const local_variable_with_holest &b)

static bool	lt_startpc (const local_variable_with_holest a, const local_variable_with_holest b)

static void	gather_transitive_predecessors (local_variable_with_holest start, const predecessor_mapt &predecessor_map, std::set< local_variable_with_holest > &result)
	See above. More...

static bool	is_store_to_slot (const java_bytecode_convert_methodt::instructiont &inst, unsigned slotidx)
	See above. More...

static void	maybe_add_hole (local_variable_with_holest &var, java_bytecode_convert_methodt::method_offsett from, java_bytecode_convert_methodt::method_offsett to)
	See above. More...

static void	populate_variable_address_map (local_variable_table_with_holest::iterator firstvar, local_variable_table_with_holest::iterator varlimit, std::vector< local_variable_with_holest * > &live_variable_at_address)
	See above. More...

static void	populate_predecessor_map (local_variable_table_with_holest::iterator firstvar, local_variable_table_with_holest::iterator varlimit, const std::vector< local_variable_with_holest * > &live_variable_at_address, const address_mapt &amap, predecessor_mapt &predecessor_map, message_handlert &msg_handler)
	Populates the `predecessor_map` with a graph from local variable table entries to their predecessors (table entries which may flow together and thus may be considered the same live range). More...

static java_bytecode_convert_methodt::method_offsett	get_common_dominator (const std::set< local_variable_with_holest * > &merge_vars, const java_cfg_dominatorst &dominator_analysis)
	Used to find out where to put a variable declaration that subsumes several variable live ranges. More...

static void	populate_live_range_holes (local_variable_with_holest &merge_into, const std::set< local_variable_with_holest * > &merge_vars, java_bytecode_convert_methodt::method_offsett expanded_live_range_start)
	See above. More...

static void	merge_variable_table_entries (local_variable_with_holest &merge_into, const std::set< local_variable_with_holest * > &merge_vars, const java_cfg_dominatorst &dominator_analysis, std::ostream &debug_out)
	See above. More...

static void	walk_to_next_index (local_variable_table_with_holest::iterator &it1, local_variable_table_with_holest::iterator &it2, local_variable_table_with_holest::iterator itend)
	Walk a vector, a contiguous block of entries with equal slot index at a time. More...

static void	cleanup_var_table (std::vector< local_variable_with_holest > &vars_with_holes)
	See above. More...

Detailed Description

Java local variable table processing.

Definition in file java_local_variable_table.cpp.

Typedef Documentation

◆ address_mapt

typedef java_bytecode_convert_methodt::address_mapt address_mapt

Definition at line 135 of file java_local_variable_table.cpp.

◆ holet

typedef java_bytecode_convert_methodt::holet holet

Definition at line 129 of file java_local_variable_table.cpp.

◆ java_cfg_dominatorst

typedef java_bytecode_convert_methodt::java_cfg_dominatorst java_cfg_dominatorst

Definition at line 137 of file java_local_variable_table.cpp.

◆ local_variable_table_with_holest

typedef java_bytecode_convert_methodt::local_variable_table_with_holest local_variable_table_with_holest

Definition at line 133 of file java_local_variable_table.cpp.

◆ local_variable_with_holest

typedef java_bytecode_convert_methodt::local_variable_with_holest local_variable_with_holest

Definition at line 131 of file java_local_variable_table.cpp.

◆ predecessor_mapt

typedef std::map< local_variable_with_holest *, std::set<local_variable_with_holest *> > predecessor_mapt

Definition at line 159 of file java_local_variable_table.cpp.

Function Documentation

◆ cleanup_var_table()

static void cleanup_var_table ( std::vector< local_variable_with_holest > & vars_with_holes )

static

See above.

Removes zero-size entries from vars_with_holes.

Parameters

vars_with_holes variable table

Definition at line 712 of file java_local_variable_table.cpp.

◆ gather_transitive_predecessors()

static void gather_transitive_predecessors	(	local_variable_with_holest *	start,
		const predecessor_mapt &	predecessor_map,
		std::set< local_variable_with_holest * > &	result
	)

static

See above.

Parameters

	start	Variable to find the predecessors of
	predecessor_map	Map from local variables to sets of predecessors
[out]	result	populated with all transitive predecessors of `start` found in `predecessor_map`

Definition at line 185 of file java_local_variable_table.cpp.

◆ get_common_dominator()

static java_bytecode_convert_methodt::method_offsett get_common_dominator	(	const std::set< local_variable_with_holest * > &	merge_vars,
		const java_cfg_dominatorst &	dominator_analysis
	)

static

Used to find out where to put a variable declaration that subsumes several variable live ranges.

Parameters

merge_vars	Set of variables we want the common dominator for
dominator_analysis	Already-initialized dominator tree

Returns: Returns the bytecode address of the closest common dominator of all given variable table entries. In the worst case the function entry point should always satisfy this criterion.

Definition at line 448 of file java_local_variable_table.cpp.

◆ is_store_to_slot()

static bool is_store_to_slot	(	const java_bytecode_convert_methodt::instructiont &	inst,
		unsigned	slotidx
	)

static

See above.

Parameters

inst	Java bytecode instruction
slotidx	local variable slot number

Returns: Returns true if inst is any form of store instruction targeting slot slotidx

Definition at line 204 of file java_local_variable_table.cpp.

◆ lt_index()

static bool lt_index	(	const local_variable_with_holest &	a,
		const local_variable_with_holest &	b
	)

static

Definition at line 141 of file java_local_variable_table.cpp.

◆ lt_startpc()

static bool lt_startpc	(	const local_variable_with_holest *	a,
		const local_variable_with_holest *	b
	)

static

Definition at line 147 of file java_local_variable_table.cpp.

◆ maybe_add_hole()

static void maybe_add_hole	(	local_variable_with_holest &	var,
		java_bytecode_convert_methodt::method_offsett	from,
		java_bytecode_convert_methodt::method_offsett	to
	)

static

See above.

Parameters

	from	bound of a gap in `var`'s live range (inclusive)
	to	bound of a gap in `var`'s live range (exclusive)
[out]	var	A hole is added to `var`, unless it would be of zero size

Definition at line 239 of file java_local_variable_table.cpp.

◆ merge_variable_table_entries()

static void merge_variable_table_entries	(	local_variable_with_holest &	merge_into,
		const std::set< local_variable_with_holest * > &	merge_vars,
		const java_cfg_dominatorst &	dominator_analysis,
		std::ostream &	debug_out
	)

static

See above.

Parameters

	merge_vars	a set of 2+ variable table entries to merge
	dominator_analysis	already-calculated dominator tree
[out]	merge_into	Populated as a combined variable table entry, with live range holes if the `merge_vars` entries do not cover a contiguous address range, beginning the combined live range at the common dominator of all `merge_vars`.
	debug_out	stream for debug output

Definition at line 539 of file java_local_variable_table.cpp.

◆ populate_live_range_holes()

static void populate_live_range_holes	(	local_variable_with_holest &	merge_into,
		const std::set< local_variable_with_holest * > &	merge_vars,
		java_bytecode_convert_methodt::method_offsett	expanded_live_range_start
	)

static

See above.

Parameters

	merge_vars	a set of 2+ variable table entries to merge
	expanded_live_range_start	address where the merged variable will be declared
[out]	merge_into	Holes are added to `merge_into`, indicating where gaps in the variable's live range fall. For example, if the declaration happens at address 10 and the entries in `merge_into` have live ranges [(20-30), (40-50)] then holes will be added at (10-20) and (30-40).

Definition at line 507 of file java_local_variable_table.cpp.

◆ populate_predecessor_map()

static void populate_predecessor_map	(	local_variable_table_with_holest::iterator	firstvar,
		local_variable_table_with_holest::iterator	varlimit,
		const std::vector< local_variable_with_holest * > &	live_variable_at_address,
		const address_mapt &	amap,
		predecessor_mapt &	predecessor_map,
		message_handlert &	msg_handler
	)

static

Populates the predecessor_map with a graph from local variable table entries to their predecessors (table entries which may flow together and thus may be considered the same live range).

Usually a live variable range begins with a store instruction initializing the relevant local variable slot, but instead of or in addition to this, control flow edges may exist from bytecode addresses that fall under a table entry which differs (or which fall under no table entry at all), but which has the same variable name and type descriptor. This indicates a split live range, and will be recorded in the predecessor map.

Parameters

	firstvar	range of local variable table entries to consider
	varlimit	range of local variable table entries to consider
	live_variable_at_address	map from bytecode address to table entry (drawn from firstvar-varlimit) live at that address
	amap	map from bytecode address to instructions, this is the CFG of the java method
[out]	predecessor_map	the output of the function, populated as described above
	msg_handler	for reporting warnings

Definition at line 303 of file java_local_variable_table.cpp.

◆ populate_variable_address_map()

static void populate_variable_address_map	(	local_variable_table_with_holest::iterator	firstvar,
		local_variable_table_with_holest::iterator	varlimit,
		std::vector< local_variable_with_holest * > &	live_variable_at_address
	)

static

See above.

Parameters

	firstvar	start of range of local variable table entries to consider
	varlimit	end of range of local variable table entries to consider
[out]	live_variable_at_address	populated with a sequence of local variable table entry pointers, such that `live_variable_at_address[addr]` yields the unique table entry covering that address. Asserts if entries overlap.

Definition at line 258 of file java_local_variable_table.cpp.

◆ walk_to_next_index()

static void walk_to_next_index	(	local_variable_table_with_holest::iterator &	it1,
		local_variable_table_with_holest::iterator &	it2,
		local_variable_table_with_holest::iterator	itend
	)

static

Walk a vector, a contiguous block of entries with equal slot index at a time.

it1 and it2 are iterators into the same vector, of which itend is the end() iterator. it1 and it2 are moved to delimit a sequence of variable table entries with slot index equal to it2->var.index on entering this function, or to both equal itend if it2==itend on entry.

Definition at line 667 of file java_local_variable_table.cpp.

Classes

Typedefs

Functions

Detailed Description

Typedef Documentation

◆ address_mapt

◆ holet

◆ java_cfg_dominatorst

◆ local_variable_table_with_holest

◆ local_variable_with_holest

◆ predecessor_mapt

Function Documentation

◆ cleanup_var_table()

◆ gather_transitive_predecessors()

◆ get_common_dominator()

◆ is_store_to_slot()

◆ lt_index()

◆ lt_startpc()

◆ maybe_add_hole()

◆ merge_variable_table_entries()

◆ populate_live_range_holes()

◆ populate_predecessor_map()

◆ populate_variable_address_map()

◆ walk_to_next_index()