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1 :	jhr	325	This directory contains the sources of Diderot compiler. The compiler is
2 :			organized into a series of passes, each of which takes a Diderot program
3 :			in some representation and produces a new representation. Here is a summary
4 :			of the passes:
5 :
6 :			1) Scanning and parsing
7 :			This phase scans and parses the Diderot source program.
8 :			(see parser)
9 :
10 :			2) Typechecking
11 :			This phase takes the parse tree and typechecks it, producing a typed
12 :			AST representation.
13 :			(see ast, basis, parser, typechecker)
14 :
15 :			3) Simplification
16 :			This takes the Typed AST representation and produces the Simple AST
17 :			representation. Simple AST only allows simple expressions over
18 :	jhr	445	variables. This phase is also responsible for loading the image
19 :			summary information. To do so, we determine which input variables are
20 :	jhr	1116	required to load the images, get the values from the user, and then
21 :	jhr	445	evaluate the static code (including using dnorm to get image info).
22 :	jhr	325	(see ast, simplify)
23 :
24 :			4) Translation to HighIL
25 :			This pass takes the Simple AST representation and translates it to
26 :			HighIL representation, which is a block-structured SSA representation.
27 :			(see basis, high-il, IL, simplify, translation)
28 :
29 :			5) HighIL optimization
30 :	jhr	430	The HighIL optimization phase is mostly a normalization phase that
31 :			lifts static computations to the global level and eliminates
32 :			dynamic field, kernel, and image values (i.e., statically resolves
33 :			them).
34 :	jhr	1116	(see high-il, IL)
35 :	jhr	325
36 :			6) Translation to MidIL
37 :	jhr	430	This pass translates the HighIL representation to MidIL. The main
38 :			purpose of this step is to replace fields with convolved images.
39 :			The MidIL includes operations to transform world-space positions
40 :			to image-space, to load voxels from images, and to evaluate kernels.
41 :			The MidIL representation supports vector operations, but tensors
42 :			with order > 1 are flattened.
43 :	jhr	325	(see high-il, high-to-mid, IL, mid-il)
44 :
45 :			7) MidIL optimization
46 :			*** Not implemented yet ***
47 :	jhr	1116	(see mid-il, IL)
48 :	jhr	325
49 :	jhr	1116	8) Translation to LowIL
50 :			This pass translates the MidIL representation to LowIL. It expands
51 :			kernel evaluations into their piecewise polynomial equivalents and
52 :			it expands out the address calculations for voxel addresses.
53 :	jhr	325	(see IL, low-il, mid-il, mid-to-low)
54 :
55 :	jhr	1116	9) LowIL optimization
56 :	jhr	325	*** Not implemented yet ***
57 :	jhr	1116	(see IL, low-il)
58 :	jhr	325
59 :	jhr	1116	10) Translation to TreeIL
60 :			The first part of code generation is to turn SSA assignments into
61 :			expression trees and to turn the CFG into block structured code.
62 :			This is accomplished by the translation from LowIL to TreeIL, which
63 :			uses the same operators and types as LowIL. This phase also includes
64 :			a transformation of the LowIL to properly handle variable scoping.
65 :			(see IL, low-il, tree-il)
66 :
67 :			11) TreeIL optimization
68 :	jhr	325	*** Not implemented yet ***
69 :	jhr	1116	This pass will cleanup some of the artifacts from the SSA form by
70 :			coalescing variables.
71 :			(see tree-il)
72 :	jhr	325
73 :	jhr	1116	12) Code generation
74 :			After translation to TreeIL, we generate code using the abstract TARGET
75 :			interface.
76 :			(see c-target, codegen, tree-il)
77 :
78 :	jhr	325	And here is a roadmap of the subdirectories:
79 :
80 :			IL - The generic IL modules that are used for the HighIL,
81 :			MidIL, and LowIL representations.
82 :			IL/gen - A simple program generator for the IL modules.
83 :			ast - The typed AST representation
84 :			basis - The definition of the Diderot Basis environment
85 :	jhr	430	c-target - Backend support for generating C code.
86 :	jhr	1116	codegen - Generic code-generation infrastructure, including the
87 :			TreeIL representation
88 :	jhr	325	common - Various miscellaneous utility modules
89 :			driver - The driver glues the various phases together
90 :			env - The environment representation used in typechecking
91 :			fields - Internal representations of image info, kernels, and
92 :			fields
93 :			high-il - The HighIL representation
94 :			high-to-mid - The HighIL to MidIL translation phase
95 :			low-il - The LowIL representation
96 :			mid-il - The MidIL representation
97 :	jhr	430	mid-to-low - The MidIL to LowIL translation phase
98 :	jhr	325	parser - The parser, scanner, and parse-tree representation.
99 :			simplify - Contains the Simple AST representation and the
100 :			simplification phase.
101 :			translate - The translation from Simple AST to High IL
102 :			typechecker - The typechecker
103 :

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