Memory Disambiguator

A memory disambiguator checks whether 2 given SSA values representing addresses alias. More...

Enumerations
enum	ir_alias_relation { ir_no_alias, ir_may_alias, ir_sure_alias }
	The alias relation of two memory addresses. More...
enum	ir_entity_usage_computed_state { ir_entity_usage_not_computed, ir_entity_usage_computed }
	The state of the entity usage flags. More...
enum	ir_disambiguator_options {   aa_opt_none = 0, aa_opt_always_alias = 1u << 0, aa_opt_type_based = 1u << 1, aa_opt_byte_type_may_alias = 1u << 2,   aa_opt_no_alias = 1u << 3, aa_opt_inherited = 1u << 4 }
	Possible options for the memory disambiguator. More...

Functions
const char *	get_ir_alias_relation_name (ir_alias_relation rel)
	Returns a human readable name for an alias relation. More...
ir_alias_relation	get_alias_relation (const ir_node *addr1, const ir_type *type1, unsigned size1, const ir_node *addr2, const ir_type *type2, unsigned size2)
	Determine if two memory addresses may point to the same memory location. More...
void	assure_irg_entity_usage_computed (ir_graph *irg)
	Assure that the entity usage flags have been computed for the given graph. More...
ir_entity_usage_computed_state	get_irp_globals_entity_usage_state (void)
	Returns the current address taken state of the globals. More...
void	set_irp_globals_entity_usage_state (ir_entity_usage_computed_state state)
	Sets the current address taken state of the globals. More...
void	assure_irp_globals_entity_usage_computed (void)
	Assure that the address taken flag is computed for the global and TLS entities (variables). More...
ir_disambiguator_options	get_irg_memory_disambiguator_options (const ir_graph *irg)
	Returns the memory disambiguator options for a graph. More...
void	set_irg_memory_disambiguator_options (ir_graph *irg, ir_disambiguator_options options)
	Sets the memory disambiguator options for a graph. More...
void	set_irp_memory_disambiguator_options (ir_disambiguator_options options)
	Sets the global disambiguator options for all graphs not having local options. More...
void	mark_private_methods (void)
	Mark all private methods, i.e. More...

Detailed Description

A memory disambiguator checks whether 2 given SSA values representing addresses alias.

Enumeration Type Documentation

enum ir_alias_relation

The alias relation of two memory addresses.

Enumerator
ir_no_alias	No alias.
ir_may_alias	Unknown state, may alias.
ir_sure_alias	Sure alias.

Definition at line 28 of file irmemory.h.

enum ir_disambiguator_options

Possible options for the memory disambiguator.

Enumerator
aa_opt_none	no options, use defaults
aa_opt_always_alias	always assume aliasing use type based alias analysis: strictly typed source language
aa_opt_type_based	if type based analysis is enabled bytes types may alias other types
aa_opt_byte_type_may_alias
aa_opt_no_alias	different addresses NEVER alias internal flag: options from a graph are inherited from global
aa_opt_inherited

Definition at line 41 of file irmemory.h.

enum ir_entity_usage_computed_state

The state of the entity usage flags.

Enumerator
ir_entity_usage_not_computed
ir_entity_usage_computed

Definition at line 35 of file irmemory.h.

Function Documentation

void assure_irg_entity_usage_computed

(

ir_graph *

irg

)

Assure that the entity usage flags have been computed for the given graph.

This analysis computes the entity usage state for all local variables.

Even then the information is not cleaned from the variables, call assure_irg_entity_usage_computed() again for recomputation.

void assure_irp_globals_entity_usage_computed

(

void

)

Assure that the address taken flag is computed for the global and TLS entities (variables).

This is an interprocedural analysis that computes the address_taken state for all global and TLS variables.

Note that this is a conservative estimation that by no Firm transformation can be invalidated, so it's only recomputed if manually triggered by calling set_irp_globals_entity_usage_state(ir_entity_usage_not_computed). Even then the information is not cleaned from the variables, call assure_irp_globals_entity_usage_computed() again for recomputation.

ir_alias_relation get_alias_relation	(	const ir_node *	addr1,
		const ir_type *	type1,
		unsigned	size1,
		const ir_node *	addr2,
		const ir_type *	type2,
		unsigned	size2
	)

Determine if two memory addresses may point to the same memory location.

This is determined by looking at the structure of the values or language rules determined by looking at the object types accessed.

Parameters

addr1	The first address.
type1	The type of the object found at addr1 ("object type").
size1	The size in bytes of the first memory access.
addr2	The second address.
type2	The type of the object found at addr2 ("object type").
size2	The size in bytes of the second memory access.

const char* get_ir_alias_relation_name

(

ir_alias_relation

rel

)

Returns a human readable name for an alias relation.

ir_disambiguator_options get_irg_memory_disambiguator_options

(

const ir_graph *

irg

)

Returns the memory disambiguator options for a graph.

Parameters

irg

the graph

ir_entity_usage_computed_state get_irp_globals_entity_usage_state

(

void

)

Returns the current address taken state of the globals.

void mark_private_methods

(

void

)

Mark all private methods, i.e.

those of which all call sites are known. We use a very conservative estimation yet: If the address of a method is never taken AND its visibility is visibility_local, then it's private.

void set_irg_memory_disambiguator_options	(	ir_graph *	irg,
		ir_disambiguator_options	options
	)

Sets the memory disambiguator options for a graph.

Parameters

irg	the graph
options	a set of options

void set_irp_globals_entity_usage_state

(

ir_entity_usage_computed_state

state

)

Sets the current address taken state of the globals.

Parameters

state

the new state

void set_irp_memory_disambiguator_options

(

ir_disambiguator_options

options

)

Sets the global disambiguator options for all graphs not having local options.

Parameters

options

a set of options