[hcoop/debian/mlton.git] / doc / guide / src / Flatten.adoc

Flatten
=======

<:Flatten:> is an optimization pass for the <:SSA:>
<:IntermediateLanguage:>, invoked from <:SSASimplify:>.

== Description ==

This pass flattens arguments to <:SSA:> constructors, blocks, and
functions.

If a tuple is explicitly available at all uses of a function
(resp. block), then:

* The formals and call sites are changed so that the components of the
tuple are passed.

* The tuple is reconstructed at the beginning of the body of the
function (resp. block).

Similarly, if a tuple is explicitly available at all uses of a
constructor, then:

* The constructor argument datatype is changed to flatten the tuple
type.

* The tuple is passed flat at each `ConApp`.

* The tuple is reconstructed at each `Case` transfer target.

== Implementation ==

* <!ViewGitFile(mlton,master,mlton/ssa/flatten.fun)>

== Details and Notes ==

{empty}
Commit	Line	Data
7f918cf1 CE	1	Flatten
	2	=======
	3
	4	<:Flatten:> is an optimization pass for the <:SSA:>
	5	<:IntermediateLanguage:>, invoked from <:SSASimplify:>.
	6
	7	== Description ==
	8
	9	This pass flattens arguments to <:SSA:> constructors, blocks, and
	10	functions.
	11
	12	If a tuple is explicitly available at all uses of a function
	13	(resp. block), then:
	14
	15	* The formals and call sites are changed so that the components of the
	16	tuple are passed.
	17
	18	* The tuple is reconstructed at the beginning of the body of the
	19	function (resp. block).
	20
	21	Similarly, if a tuple is explicitly available at all uses of a
	22	constructor, then:
	23
	24	* The constructor argument datatype is changed to flatten the tuple
	25	type.
	26
	27	* The tuple is passed flat at each `ConApp`.
	28
	29	* The tuple is reconstructed at each `Case` transfer target.
	30
	31	== Implementation ==
	32
	33	* <!ViewGitFile(mlton,master,mlton/ssa/flatten.fun)>
	34
	35	== Details and Notes ==
	36
	37	{empty}