summaryrefslogtreecommitdiff
path: root/doc/index.html
blob: 9108a58e83dd451f14caeb7c80a77f614860b469 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<HTML>
<HEAD>
<TITLE>The Compcert verified compiler</TITLE>
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1">

<style type="text/css">
body {
  color: black; background: white;
  margin-left: 5%; margin-right: 5%;
}
h2 { margin-left: -5%;}
h3 { margin-left: -3%; }
h1,h2,h3 { font-family: sans-serif; }
hr { margin-left: -5%; margin-right:-5%; }
a:visited {color : #416DFF; text-decoration : none; font-weight : bold}
a:link {color : #416DFF; text-decoration : none; font-weight : bold}
a:hover {color : Red; text-decoration : underline; }
a:active {color : Red; text-decoration : underline; }
</style>

</HEAD>
<BODY>

<H1 align="center">The Compcert verified compiler</H1>
<H2 align="center">Commented Coq development</H2>
<H3 align="center">Version 1.8.1, 2011-03-14</H3>

<H2>Introduction</H2>

<P>Compcert is a compiler that generates PowerPC, ARM and x86 assembly
code from Compcert C, a large subset of the C programming language.
The particularity of this compiler is that it is written mostly within
the specification language of the Coq proof assistant, and its
correctness --- the fact that the generated assembly code is
semantically equivalent to its source program --- was entirely proved
within the Coq proof assistant.</P>

<P>High-level descriptions of the Compcert compiler and its proof of 
correctness can be found in the following papers (in increasing order of technical details):</P>
<UL>
<LI>Xavier Leroy, <A HREF="http://gallium.inria.fr/~xleroy/publi/compcert-CACM.pdf">Formal verification of a realistic compiler</A>.  Communications of the ACM 52(7), July 2009.
<LI>Sandrine Blazy, Zaynah Dargaye and Xavier Leroy,
<A HREF="http://gallium.inria.fr/~xleroy/publi/cfront.pdf">Formal
verification of a C compiler front-end</A>. 
Proceedings of Formal Methods 2006, LNCS 4085.
<LI>Xavier Leroy, <A HREF="http://gallium.inria.fr/~xleroy/publi/compcert-backend.pdf">A formally verified compiler back-end</A>. 
Journal of Automated Reasoning 43(4):363-446, 2009.
</UL>

<P>This Web site gives a commented listing of the underlying Coq
specifications and proofs.  Proof scripts and the parts of the
compiler written directly in Caml are omitted.  This development is a
work in progress; some parts have substantially changed since the
overview papers above were written.</P>

<P>The complete sources for Compcert can be downloaded from
<A HREF="http://compcert.inria.fr/">the Compcert Web site</A>.</P>

<P>This document and the Compcert sources are
copyright 2005, 2006, 2007, 2008, 2009, 2010, 2011 Institut National de Recherche en
Informatique et en Automatique (INRIA) and distributed under the terms
of the following <A HREF="LICENSE">license</A>.
</P>

<H2>Table of contents</H2>

<H3>General-purpose libraries, data structures and algorithms</H3>

<UL>
<LI> <A HREF="html/Coqlib.html">Coqlib</A>: addendum to the Coq standard library.
<LI> <A HREF="html/Maps.html">Maps</A>: finite maps.
<LI> <A HREF="html/Integers.html">Integers</A>: machine integers.
<LI> <A HREF="html/Floats.html">Floats</A>: machine floating-point numbers.
<LI> <A HREF="html/Iteration.html">Iteration</A>: various forms of "while" loops.
<LI> <A HREF="html/Ordered.html">Ordered</A>: construction of
ordered types.
<LI> <A HREF="html/Lattice.html">Lattice</A>: construction of
semi-lattices.
<LI> <A HREF="html/Kildall.html">Kildall</A>: resolution of dataflow
inequations by fixpoint iteration.
<LI> <A HREF="html/Parmov.html">Parmov</A>: compilation of parallel assignments.
<LI> <A HREF="html/UnionFind.html">UnionFind</A>: a persistent union-find data structure.
</UL>

<H3>Definitions and theorems used in many parts of the development</H3>

<UL>
<LI> <A HREF="html/Errors.html">Errors</A>: the Error monad.
<LI> <A HREF="html/AST.html">AST</A>: identifiers, whole programs and other
common elements of abstract syntaxes.
<LI> <A HREF="html/Values.html">Values</A>: run-time values.
<LI> <A HREF="html/Events.html">Events</A>: observable events and traces.
<LI> <A HREF="html/Memtype.html">Memtype</A>: memory model (interface). <BR>
See also: <A HREF="html/Memory.html">Memory</A> (implementation of the memory model). <BR>
See also: <A HREF="html/Memdata.html">Memdata</A> (in-memory representation of data).
<LI> <A HREF="html/Globalenvs.html">Globalenvs</A>: global execution environments.
<LI> <A HREF="html/Smallstep.html">Smallstep</A>: tools for small-step semantics.
<LI> <A HREF="html/Determinism.html">Determinism</A>: determinism properties of small-step semantics.
<LI> <A HREF="html/Op.html">Op</A>: operators, addressing modes and their
semantics.
</UL>

<H3>Source, intermediate and target languages: syntax and semantics</H3>

<UL>
<LI> The Compcert C source language:
<A HREF="html/Csyntax.html">syntax</A> and
<A HREF="html/Csem.html">semantics</A> and
<A HREF="html/Cstrategy.html">determinized semantics</A>.
<LI> <A HREF="html/Clight.html">Clight</A>: a simpler version of Cmedium where expressions contain no side-effects.
<LI> <A HREF="html/Csharpminor.html">Csharpminor</A>: low-level
 structured language.
<LI> <A HREF="html/Cminor.html">Cminor</A>: low-level structured
language, with explicit stack allocation of certain local variables.
<LI> <A HREF="html/CminorSel.html">CminorSel</A>: like Cminor,
with machine-specific operators and addressing modes.
<LI> <A HREF="html/RTL.html">RTL</A>: register transfer language (3-address
code, control-flow graph, infinitely many pseudo-registers). <BR>
See also: <A HREF="html/Registers.html">Registers</A> (representation of
pseudo-registers).
<LI> <A HREF="html/LTL.html">LTL</A>: location transfer language (3-address
code, control-flow graph, finitely many physical registers, infinitely
many stack slots). <BR>
See also: <A HREF="html/Locations.html">Locations</A> (representation of
locations).
<LI> <A HREF="html/LTLin.html">LTLin</A>: like LTL, but the CFG is
replaced by a linear list of instructions with explicit branches and labels.
<LI> <A HREF="html/Linear.html">Linear</A>: like LTLin, with explicit
spilling, reloading and enforcement of calling conventions.
<LI> <A HREF="html/Mach.html">Mach</A>: like Linear, with a more concrete
view of the activation record.  <BR>
See also: <A HREF="html/Machabstr.html">Machabstr</A> abstract semantics for Mach. <BR>
See also: <A HREF="html/Machconcr.html">Machconcr</A> concrete semantics for Mach.
<LI> <A HREF="html/Asm.html">Asm</A>: abstract syntax for PowerPC assembly
code.
</UL>

<H3>Compiler passes</H3>

<TABLE cellpadding="5%">
<TR valign="top">
  <TH>Pass</TH>
  <TH>Source &amp; target</TH>
  <TH>Compiler&nbsp;code</TH>
  <TH>Correctness&nbsp;proof</TH>
</TR>

<TR valign="top">
  <TD>Pulling side-effects out of expressions;<br>
      fixing an evaluation order</TD>
  <TD>Compcert C to Clight</TD>
  <TD><A HREF="html/SimplExpr.html">SimplExpr</A></TD>
  <TD><A HREF="html/SimplExprspec.html">SimplExprspec</A><br>
      <A HREF="html/SimplExprproof.html">SimplExprproof</A></TD>
</TR>
<TR valign="top">
  <TD>Simplification of control structures; <br>
      explication of type-dependent computations</TD>
  <TD>Clight to Csharpminor</TD>
  <TD><A HREF="html/Cshmgen.html">Cshmgen</A></TD>
  <TD><A HREF="html/Cshmgenproof.html">Cshmgenproof</A></TD>
</TR>
<TR valign="top">
  <TD>Stack allocation of local variables<br>
      whose address is taken;<br>
      simplification of switch statements</TD>
  <TD>Csharpminor to Cminor</TD>
  <TD><A HREF="html/Cminorgen.html">Cminorgen</A></TD>
  <TD><A HREF="html/Cminorgenproof.html">Cminorgenproof</A></TD>
</TR>

<TR valign="top">
  <TD>Recognition of operators<br>and addressing modes</TD>
  <TD>Cminor to CminorSel</TD>
  <TD><A HREF="html/Selection.html">Selection</A><br>
      <A HREF="html/SelectOp.html">SelectOp</A></TD>
  <TD><A HREF="html/Selectionproof.html">Selectionproof</A><br>
      <A HREF="html/SelectOpproof.html">SelectOpproof</A></TD>
</TR>

<TR valign="top">
  <TD>Construction of the CFG, <br>3-address code generation</TD>
  <TD>Cminor to RTL</TD>
  <TD><A HREF="html/RTLgen.html">RTLgen</A></TD>
  <TD><A HREF="html/RTLgenspec.html">RTLgenspec</A><BR>
      <A HREF="html/RTLgenproof.html">RTLgenproof</A></TD>
</TR>

<TR valign="top">
  <TD>Recognition of tail calls</TD>
  <TD>RTL to RTL</TD>
  <TD><A HREF="html/Tailcall.html">Tailcall</A></TD>
  <TD><A HREF="html/Tailcallproof.html">Tailcallproof</A></TD>
</TR>

<TR valign="top">
  <TD>Constant propagation</TD>
  <TD>RTL to RTL</TD>
  <TD><A HREF="html/Constprop.html">Constprop</A><br>
      <A HREF="html/ConstpropOp.html">ConstpropOp</A></TD>
  <TD><A HREF="html/Constpropproof.html">Constpropproof</A><br>
      <A HREF="html/ConstpropOpproof.html">ConstproppOproof</A></TD>
</TR>

<TR valign="top">
  <TD>Common subexpression elimination</TD>
  <TD>RTL to RTL</TD>
  <TD><A HREF="html/CSE.html">CSE</A></TD>
  <TD><A HREF="html/CSEproof.html">CSEproof</A></TD>
</TR>

<TR valign="top">
  <TD>Elimination of redundant casts</TD>
  <TD>RTL to RTL</TD>
  <TD><A HREF="html/CastOptim.html">CastOptim</A></TD>
  <TD><A HREF="html/CastOptimproof.html">CastOptimproof</A></TD>
</TR>

<TR valign="top">
  <TD>Register allocation by coloring<br>of an interference graph</TD>
  <TD>RTL to LTL</TD>
  <TD><A HREF="html/InterfGraph.html">InterfGraph</A><BR>
      <A HREF="html/Coloring.html">Coloring</A><BR>
      <A HREF="html/Allocation.html">Allocation</A></TD>
  <TD><BR>
      <A HREF="html/Coloringproof.html">Coloringproof</A><BR>
      <A HREF="html/Allocproof.html">Allocproof</A></TD>
</TR>

<TR valign="top">
  <TD>Branch tunneling</TD>
  <TD>LTL to LTL</TD>
  <TD><A HREF="html/Tunneling.html">Tunneling</A></TD>
  <TD><A HREF="html/Tunnelingproof.html">Tunnelingproof</A></TD>
</TR>

<TR valign="top">
  <TD>Linearization of the CFG</TD>
  <TD>LTL to LTLin</TD>
  <TD><A HREF="html/Linearize.html">Linearize</A></TD>
  <TD><A HREF="html/Linearizeproof.html">Linearizeproof</A></TD>
</TR>

<TR valign="top">
  <TD>Spilling, reloading, calling conventions</TD>
  <TD>LTLin to Linear</TD>
  <TD><A HREF="html/Conventions.html">Conventions</A><BR>
      <A HREF="html/Reload.html">Reload</A></TD>
  <TD><A HREF="html/Parallelmove.html">Parallelmove</A><BR>
      <A HREF="html/Reloadproof.html">Reloadproof</A></TD>
</TR>

<TR valign="top">
  <TD>Laying out the activation records</TD>
  <TD>Linear to Mach</TD>
  <TD><A HREF="html/Bounds.html">Bounds</A><BR>
      <A HREF="html/Stacking.html">Stacking</A></TD>
  <TD><A HREF="html/Stackingproof.html">Stackingproof</A></TD>
</TR>

<TR valign="top">
  <TD>Storing the activation records in memory</TD>
  <TD>Mach to Mach</TD>
  <TD>(none)
  <TD><A HREF="html/Asmgenretaddr.html">Asmgenretaddr</A><BR>
      <A HREF="html/Machabstr2concr.html">Machabstr2concr</A></TD>

<TR valign="top">
  <TD>Emission of assembly code</TD>
  <TD>Mach to Asm</TD>
  <TD><A HREF="html/Asmgen.html">Asmgen</A></TD>
  <TD><A HREF="html/Asmgenproof1.html">Asmgenproof1</A><BR>
      <A HREF="html/Asmgenproof.html">Asmgenproof</A></TD>
</TR>
</TABLE>

<H3>Type systems</H3>

Trivial type systems are used to statically capture well-formedness
conditions on the source and intermediate languages.
<UL>
<LI> <A HREF="html/RTLtyping.html">RTLtyping</A>: typing for RTL + type
reconstruction.
<LI> <A HREF="html/LTLtyping.html">LTLtyping</A>: typing for LTL.
<LI> <A HREF="html/LTLintyping.html">LTLintyping</A>: typing for LTLin.
<LI> <A HREF="html/Lineartyping.html">Lineartyping</A>: typing for Linear.
<LI> <A HREF="html/Machtyping.html">Machtyping</A>: typing for Mach.
</UL>
Proofs that compiler passes are type-preserving:
<UL>
<LI> <A HREF="html/Alloctyping.html">Alloctyping</A> (register allocation).
<LI> <A HREF="html/Tunnelingtyping.html">Tunnelingtyping</A> (branch tunneling).
<LI> <A HREF="html/Linearizetyping.html">Linearizetyping</A> (code linearization).
<LI> <A HREF="html/Reloadtyping.html">Reloadtyping</A> (spilling and reloading).
<LI> <A HREF="html/Stackingtyping.html">Stackingtyping</A> (layout of activation records).
</UL>

<H3>All together</H3>

<UL>
<LI> <A HREF="html/Compiler.html">Compiler</A>: composing the passes together;
whole-compiler semantic preservation theorems.
<LI> <A HREF="html/Complements.html">Complements</A>: interesting consequences of the semantic preservation theorems.
</UL>

<HR>
<ADDRESS>Xavier.Leroy@inria.fr</ADDRESS>
<HR>

</BODY>
</HTML>