Module Peephole

module Peephole: sig .. end

Peephole optimizations over jump-less instruction lists.

Rewriting rules

type rewriting_rules = (Utils.u2 * Instruction.t) list -> (Utils.u2 * Instruction.t) list

The type of function rewriting (line, instruction) lists.

val optimize_constants : rewriting_rules

Predefined rules to optimize constants.

val optimize_locals : rewriting_rules

Predefined rules to optimize local accesses.

val avoid_conv : rewriting_rules

Predefined rules to avoid simple conversions.

val remove_nops_and_unused_pushed_values : rewriting_rules

Predefined rules to remove no-ops.

val optimize_iinc : rewriting_rules

Predefined rules to optimize iinc instructions.

val remove_load_store : rewriting_rules

Predefined rules to optimize load/store sequences.

val remove_get_put : rewriting_rules

Predefined rules to optimize get/put sequences.

val rewrite_store_store : rewriting_rules

Predefined rules to optimize store/store sequences.

val rewrite_store_load : rewriting_rules

Predefined rules to optimize store/load sequences.

val rewrite_load_load : rewriting_rules

Predefined rules to optimize load/load sequences.

val constant_on_the_top : rewriting_rules

Predefined rules to move constants on the top.

val remove_neutral_elements : rewriting_rules

Predefined rules to remove neutral elements.

val rewrite_absorbing_elements : rewriting_rules

Predefined rules to simplify by absorbing elements.

val apply_stength_reduction : rewriting_rules

Predefined rules to apply stength reduction.

val remove_identity : rewriting_rules

Predefined rules to remove identities.

val all_rules : rewriting_rules list

The list of all predefined rewriting rules, that is (in order):

optimize_constants;
optimize_locals;
remove_nops_and_unused_pushed_values;
optimize_iinc;
remove_load_store;
remove_get_put;
rewrite_store_store;
rewrite_store_load;
rewrite_load_load;
constant_on_the_top;
remove_neutral_elements;
rewrite_absorbing_elements;
apply_stength_reduction;
remove_identity.

type position =

`\|`	`Head`	`(*`	Insert rule at the list begin.	`*)`
`\|`	`Tail`	`(*`	Insert rule at the list end.	`*)`
`\|`	`Before of rewriting_rules`	`(*`	Insert rule before specified one.	`*)`
`\|`	`After of rewriting_rules`	`(*`	Insert rule before specified one.	`*)`

Type defining where a rule should be added inside a list.

val insert : rewriting_rules ->
       position ->
       rewriting_rules list -> rewriting_rules list

insert r p l inserts rule r into list l at position p, using physical equality to compare rewriting rules.

Raises Not_found if p references rewriting rules not present in the list.

Application of rewriting rules

val optimize_list : ?rules:rewriting_rules list ->
       (Utils.u2 * Instruction.t) list -> (Utils.u2 * Instruction.t) list

optimize_list ~rules:l l2 optimizes l2 by applying the the list of rewriting rules l until a fixpoint is reached.

WARNING: offset are not rewritten, meaning that l2 should not contain any jump instruction.

val optimize_graph : ?rules:rewriting_rules list ->
       ('a * Utils.u2 list, 'b) ControlFlow.graph ->
       ('a * Utils.u2 list, 'b) ControlFlow.graph

optimize_graph ~rules:l g returns a graph similar to g, except that every instruction list has been optimized, l being the list of rewriting rules to apply to instruction lists (until a fixpoint is reached).