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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<HTML>
<HEAD>
<TITLE>The CompCert verified compiler</TITLE>
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<font color=gray>
<H1 align="center">The CompCert verified compiler</H1>
<H2 align="center">Commented Coq development</H2>
<H3 align="center">Version 3.10, 2021-11-19</H3>
</font>
<H3 align="center"><a href="https://www-verimag.imag.fr">VERIMAG</a> fork version 2021-12-07</H3>
<H2>The CompCert Verimag's fork</H2>
<p>This web page is a patched version of the table of contents of the official CompCert sources documentation, as given on <A HREF="http://compcert.org/doc/index.html">the CompCert Web site</A>.
The unmodified parts of this table appear in <font color=gray>gray</font>.
<br>
<br>
A high-level view of this CompCert backend is provided by the following documents:
<ul>
<li><a href="https://gricad-gitlab.univ-grenoble-alpes.fr/certicompil/compcert-kvx">The Git repo README.md</a>.</li>
<li><a href="http://www-verimag.imag.fr/~boulme/videos/poster-oopsla20.mp4">A 5-minutes video</a> by C. Six, presenting the postpass scheduling and the KVX backend
(also on <a href="https://www.youtube.com/watch?v=RAzMDS9OVSw">YouTube if you need subtitles</a>).</li>
<li><a href="https://hal.archives-ouvertes.fr/hal-02185883">Certified and Efficient Instruction Scheduling</a>, an OOPSLA'20 paper, by Six, Boulmé and Monniaux.</li>
<li><a href="https://hal.archives-ouvertes.fr/hal-03200774">Formally Verified Superblock Scheduling</a>, a CPP'22 paper, by Six, Gourdin, Boulmé, Monniaux, Fasse and Nardino.</li>
<li><a href="https://hal.archives-ouvertes.fr/tel-03326923">Optimized and formally-verified compilation for a VLIW processor</a>, Phd Thesis of Cyril Six in 2021.</li>
<li><a href="https://hal.archives-ouvertes.fr/tel-03356701">Formally Verified Defensive Programming (efficient Coq-verified computations from untrusted ML oracles) – Chapters 1 to 3</a>, Habilitation Thesis of Sylvain Boulmé in 2021.</li>
<li><a href="https://www-verimag.imag.fr/~boulme/CPP_2022/FASSE-Justus-MSc-Thesis_2021.pdf">Code Transformations to Increase Prepass Scheduling Opportunities in CompCert</a>, MSc Thesis of Justus Fasse in 2021.</li>
<li><a href="https://www-verimag.imag.fr/~boulme/CPP_2022/NARDINO-Nicolas-BSc-Thesis_2021.pdf">Register-Pressure-Aware Prepass-Scheduling for CompCert</a>, BSc Thesis of Nicolas Nardino in 2021.</li>
<li><a href="https://www.lirmm.fr/afadl2021/papers/afadl2021_paper_9.pdf">Formally verified postpass scheduling with peephole optimization for AArch64</a>, a short AFADL'21 paper, by Gourdin.</li>
</ul>
<p>The people responsible for this version are</p>
<ul>
<li>Sylvain Boulmé (Grenoble-INP, Verimag)</li>
<li>David Monniaux (CNRS, Verimag)</li>
<li>Cyril Six (Kalray)</li>
<li>Léo Gourdin (UGA, Verimag)</li>
</ul>
<p>with contributions of:</p>
<ul>
<li>Justus Fasse (M2R UGA, now at KU Leuven).</li>
<li>Pierre Goutagny and Nicolas Nardino (L3 ENS-Lyon).</li>
</ul>
</p>
<H2>Introduction</H2>
<font color="gray">
<P>CompCert is a compiler that generates PowerPC, ARM, RISC-V 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="https://xavierleroy.org/publi/compcert-CACM.pdf">Formal verification of a realistic compiler</A>. Communications of the ACM 52(7), July 2009.
<LI>Xavier Leroy, <A HREF="https://xavierleroy.org/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 are folded by default, but
can be viewed by clicking on "Proof". Some modules (written in <I>italics</I> below) differ between the five target architectures. The
PowerPC versions of these modules are shown below; the AArch64, ARM,
x86 and RISC-V versions can be found in the source distribution.
</P>
<P> 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="https://github.com/AbsInt/CompCert/">the Git repository</A>
or <A HREF="https://compcert.org/">the CompCert Web site</A>.
</P>
<P>This document and the CompCert sources are copyright Institut
National de Recherche en Informatique et en Automatique (INRIA) and
AbsInt Angewandte Informatik GmbH, and are distributed under the terms of the
following <A HREF="https://compcert.org/doc/LICENSE.txt">license</A>.
</P>
</font>
<H2>Table of contents</H2>
<font color="gray">
<H3>General-purpose libraries, data structures and algorithms</H3>
<UL>
<LI> <A HREF="html/compcert.lib.Coqlib.html">Coqlib</A>: addendum to the Coq standard library.
<LI> <A HREF="html/compcert.lib.Maps.html">Maps</A>: finite maps.
<LI> <A HREF="html/compcert.lib.Integers.html">Integers</A>: machine integers.
<LI> <A HREF="html/compcert.lib.Floats.html">Floats</A>: machine floating-point numbers.
<LI> <A HREF="html/compcert.lib.Iteration.html">Iteration</A>: various forms of "while" loops.
<LI> <A HREF="html/compcert.lib.Ordered.html">Ordered</A>: construction of
ordered types.
<LI> <A HREF="html/compcert.lib.Lattice.html">Lattice</A>: construction of
semi-lattices.
<LI> <A HREF="html/compcert.backend.Kildall.html">Kildall</A>: resolution of dataflow
inequations by fixpoint iteration.
<LI> <A HREF="html/compcert.lib.UnionFind.html">UnionFind</A>: a persistent union-find data structure.
<LI> <A HREF="html/compcert.lib.Postorder.html">Postorder</A>: postorder numbering of a directed graph.
</UL></font>
<H4><A HREF=https://github.com/boulme/ImpureDemo>The Impure library</A> (of Boulmé)</H4>
<UL>
<LI><A HREF="html/compcert.lib.Impure.ImpConfig.html">ImpConfig</A>: declares the <tt>Impure</tt> monad and defines its extraction.</LI>
<LI><A HREF="html/compcert.lib.Impure.ImpCore.html">ImpCore</A>: defines notations for the <tt>Impure</tt> monad and a <tt>wlp_simplify</tt> tactic (to reason about <tt>Impure</tt> functions in a Hoare-logic style).</LI>
<LI><A HREF="html/compcert.lib.Impure.ImpLoops.html">ImpLoops</A>, <A HREF="html/compcert.lib.Impure.ImpIO.html">ImpIO</A>, <A HREF="html/compcert.lib.Impure.ImpHCons.html">ImpHCons</A>: declare <tt>Impure</tt> oracles and define operators from these oracles. <A HREF="html/compcert.lib.Impure.ImpExtern.html">ImpExtern</A> exports all these impure operators.</LI>
<LI><A HREF="html/compcert.lib.Impure.ImpMonads.html">ImpMonads</A>: axioms of "impure computations" and some Coq models of these axioms.</LI>
<LI><A HREF="html/compcert.lib.Impure.ImpPrelude.html">ImpPrelude</A>: declares the data types exchanged with <tt>Impure</tt> oracles.</LI>
</UL>
<H4 id="abstractbb">The <tt>abstractbb</tt> library, introduced for Aarch64 and KVX cores</H4>
This library introduces a block intermediate representation used for postpass scheduling verification. It might be extended to others backends.
<UL>
<LI> <A HREF="html/compcert.scheduling.abstractbb.AbstractBasicBlocksDef.html">AbstractBasicBlocksDef</A>: an IR for verifying some semantic properties on basic-blocks.
<LI> <A HREF="html/compcert.scheduling.abstractbb.Parallelizability.html">Parallelizability</A>: verifying that sequential and parallel semantics are equivalent for a given abstract basic-block.
<LI> <A HREF="html/compcert.scheduling.abstractbb.ImpSimuTest.html">ImpSimuTest</A>: verifying that a given abstract basic-block is simulated by another one for sequential semantics. This module refines <A HREF="html/compcert.scheduling.abstractbb.SeqSimuTheory.html">SeqSimuTheory</A> with hash-consing and uses <A HREF=https://github.com/boulme/ImpureDemo>the Impure library</A> to reason on physical equality and handling of imperative code in Coq.
</UL>
<font color=gray>
<H3>Definitions and theorems used in many parts of the development</H3>
<UL>
<LI> <A HREF="html/compcert.common.Errors.html">Errors</A>: the Error monad.
<LI> <A HREF="html/compcert.common.AST.html">AST</A>: identifiers, whole programs and other
common elements of abstract syntaxes.
<LI> <A HREF="html/compcert.common.Linking.html">Linking</A>: generic framework to define syntactic linking over the CompCert languages.
<LI> <A HREF="html/compcert.common.Values.html">Values</A>: run-time values.
<LI> <A HREF="html/compcert.common.Events.html">Events</A>: observable events and traces.
<LI> <A HREF="html/compcert.common.Memory.html">Memory</A>: memory model. <BR>
See also: <A HREF="html/compcert.common.Memdata.html">Memdata</A> (in-memory representation of data).
<LI> <A HREF="html/compcert.common.Globalenvs.html">Globalenvs</A>: global execution environments.
<LI> <A HREF="html/compcert.common.Smallstep.html">Smallstep</A>: tools for small-step semantics.
<LI> <A HREF="html/compcert.common.Behaviors.html">Behaviors</A>: from small-step semantics to observable behaviors of programs.
<LI> <A HREF="html/compcert.common.Determinism.html">Determinism</A>: determinism properties of small-step semantics.
<LI> <A HREF="html/compcert.kvx.Op.html"><I>Op</I></A>: operators, addressing modes and their
semantics.
<LI> <A HREF="html/compcert.common.Builtins.html">Builtins</A>: semantics of built-in functions. <BR>
See also: <A HREF="html/compcert.common.Builtins0.html">Builtins0</A> (target-independent part), <A HREF="html/compcert.kvx.Builtins1.html"><I>Builtins1</I></A> (target-dependent part).
<LI> <A HREF="html/compcert.common.Unityping.html">Unityping</A>: a solver for atomic unification constraints.
</UL>
<H3>Source, intermediate and target languages: syntax and semantics</H3>
<UL>
<LI> The CompCert C source language:
<A HREF="html/compcert.cfrontend.Csyntax.html">syntax</A> and
<A HREF="html/compcert.cfrontend.Csem.html">semantics</A> and
<A HREF="html/compcert.cfrontend.Cstrategy.html">determinized semantics</A> and
<A HREF="html/compcert.cfrontend.Ctyping.html">type system</A>.<BR>
See also: <A HREF="html/compcert.cfrontend.Ctypes.html">type expressions</A> and
<A HREF="html/compcert.cfrontend.Cop.html">operators (syntax and semantics)</A>.<BR>
See also: <A HREF="html/compcert.cfrontend.Cexec.html">reference interpreter</A>.
<LI> <A HREF="html/compcert.cfrontend.Clight.html">Clight</A>: a simpler version of CompCert C where expressions contain no side-effects.
<LI> <A HREF="html/compcert.cfrontend.Csharpminor.html">Csharpminor</A>: low-level
structured language.
<LI> <A HREF="html/compcert.backend.Cminor.html">Cminor</A>: low-level structured
language, with explicit stack allocation of certain local variables.
<LI> <A HREF="html/compcert.backend.CminorSel.html">CminorSel</A>: like Cminor,
with machine-specific operators and addressing modes.
<LI> <A HREF="html/compcert.backend.RTL.html">RTL</A>: register transfer language (3-address
code, control-flow graph, infinitely many pseudo-registers). <BR>
See also: <A HREF="html/compcert.backend.Registers.html">Registers</A> (representation of
pseudo-registers).
<LI> <A HREF="html/compcert.backend.LTL.html">LTL</A>: location transfer language (3-address
code, control-flow graph of basic blocks, finitely many physical registers, infinitely
many stack slots). <BR>
See also: <A HREF="html/compcert.backend.Locations.html">Locations</A> (representation of
locations) and <A HREF="html/compcert.kvx.Machregs.html"><I>Machregs</I></A> (description of processor registers).
<LI> <A HREF="html/compcert.backend.Linear.html">Linear</A>: like LTL, but the CFG is
replaced by a linear list of instructions with explicit branches and labels.
<LI> <A HREF="html/compcert.backend.Mach.html">Mach</A>: like Linear, with a more concrete
view of the activation record.
<LI> <A HREF="html/compcert.kvx.Asm.html"><I>Asm</I></A>: abstract syntax for PowerPC assembly
code.
</font>
<H4>Languages introduced in the VERIMAG version</H4>
Generic (or possibly adaptable) Intermediate Representations (IR):
<UL>
<LI> <A HREF="html/compcert.scheduling.BTL.html">BTL</A>: an IR dedicated to defensive certification of middle-end optimizations (before register allocation).
BTL stands for "Block Transfer Language". <!-- TODO add a link to some markdown draft here -->
<LI> <A HREF="html/compcert.scheduling.postpass_lib.Machblock.html">Machblock</A>: a variant of Mach, with a syntax for basic-blocks, and a block-step semantics (execute one basic-block in one step).
This IR is generic over the processor and used for KVX and Aarch64.
<LI> <A HREF="html/compcert.kvx.Asmblock.html"><I>Asmblock</I></A>: a variant of Asm, with a big-step semantics of basic-blocks.
This IR is an intermediate step between Machblock and Asm on backends featuring postpass scheduling (KVX and Aarch64).
<LI> <A HREF="#abstractbb"><I>AbstractBasicBlocks</I></A>: the AbstractBasicBlocks Domain Specific Language (DSL) used in the postpass scheduling verification.
This DSL is only used as a library on KVX and Aarch64.
</UL>
Specific to KVX:
<UL>
<LI> <A HREF="html/compcert.kvx.Asmvliw.html"><I>Asmvliw</I></A>: abstract syntax and semantics for KVX VLIW assembly: atomic instructions are grouped by "bundles". These bundles are executed sequentially, but execution is parallel within bundles.
<LI> <A HREF="html/compcert.kvx.Asm.html"><I>kvx/Asm</I></A>: a variant of Asmvliw with a flat syntax for bundles, instead of a structured one (bundle termination is encoded as a pseudo-instruction). This IR is mainly a wrapper of <I>Asmvliw</I> for a smooth integration in CompCert (and an easier pretty-printing of the abstract syntax).
</UL>
<H3>Compiler passes</H3>
<TABLE cellpadding="5%" style="color:#808080">
<TR valign="top">
<TH align=left>Pass</TH>
<TH align=left>Source & target</TH>
<TH align=left>Compiler code</TH>
<TH align=left>Correctness 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/compcert.cfrontend.SimplExpr.html">SimplExpr</A></TD>
<TD><A HREF="html/compcert.cfrontend.SimplExprspec.html">SimplExprspec</A><br>
<A HREF="html/compcert.cfrontend.SimplExprproof.html">SimplExprproof</A></TD>
</TR>
<TR valign="top">
<TD>Pulling non-adressable scalar local variables out of memory</TD>
<TD>Clight to Clight</TD>
<TD><A HREF="html/compcert.cfrontend.SimplLocals.html">SimplLocals</A></TD>
<TD><A HREF="html/compcert.cfrontend.SimplLocalsproof.html">SimplLocalsproof</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/compcert.cfrontend.Cshmgen.html">Cshmgen</A></TD>
<TD><A HREF="html/compcert.cfrontend.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/compcert.cfrontend.Cminorgen.html">Cminorgen</A></TD>
<TD><A HREF="html/compcert.cfrontend.Cminorgenproof.html">Cminorgenproof</A></TD>
</TR>
<TR valign="top">
<TD>Recognition of operators<br>and addressing modes;<br>
if-conversion</TD>
<TD>Cminor to CminorSel</TD>
<TD><A HREF="html/compcert.backend.Selection.html">Selection</A><br>
<A HREF="html/compcert.kvx.SelectOp.html"><I>SelectOp</I></A><br>
<A HREF="html/compcert.kvx.SelectLong.html"><I>SelectLong</I></A><br>
<A HREF="html/compcert.backend.SelectDiv.html">SelectDiv</A><br>
<A HREF="html/compcert.backend.SplitLong.html">SplitLong</A></TD>
<TD><A HREF="html/compcert.backend.Selectionproof.html">Selectionproof</A><br>
<A HREF="html/compcert.kvx.SelectOpproof.html"><I>SelectOpproof</I></A><br>
<A HREF="html/compcert.kvx.SelectLongproof.html"><I>SelectLongproof</I></A><br>
<A HREF="html/compcert.backend.SelectDivproof.html">SelectDivproof</A><br>
<A HREF="html/compcert.backend.SplitLongproof.html">SplitLongproof</A></TD>
</TR>
<TR valign="top">
<TD>Construction of the CFG, <br>3-address code generation</TD>
<TD>CminorSel to RTL</TD>
<TD><A HREF="html/compcert.backend.RTLgen.html">RTLgen</A></TD>
<TD><A HREF="html/compcert.backend.RTLgenspec.html">RTLgenspec</A><BR>
<A HREF="html/compcert.backend.RTLgenproof.html">RTLgenproof</A></TD>
</TR>
<TR valign="top">
<TD>Recognition of tail calls</TD>
<TD>RTL to RTL</TD>
<TD><A HREF="html/compcert.backend.Tailcall.html">Tailcall</A></TD>
<TD><A HREF="html/compcert.backend.Tailcallproof.html">Tailcallproof</A></TD>
</TR>
<TR valign="top">
<TD>Function inlining</TD>
<TD>RTL to RTL</TD>
<TD><A HREF="html/compcert.backend.Inlining.html">Inlining</A></TD>
<TD><A HREF="html/compcert.backend.Inliningspec.html">Inliningspec</A><BR>
<A HREF="html/compcert.backend.Inliningproof.html">Inliningproof</A></TD>
</TR>
<TR valign="top" style="color:#000000">
<TD colspan="4"><b>Passes introduced for profiling (for later use in trace selection)</b></TD>
</TR>
<TR valign="top" style="color:#000000">
<TD>Insert profiling annotations (for recording experiments -- see PROFILE.md).
</TD>
<TD>RTL to RTL</TD>
<TD><A HREF="html/compcert.backend.Profiling.html">Profiling</A></TD>
<TD><A HREF="html/compcert.backend.Profilingproof.html">Profilingproof</A></TD>
</TR>
<TR valign="top" style="color:#000000">
<TD>Update ICond nodes (from recorded experiments -- see PROFILE.md).
</TD>
<TD>RTL to RTL</TD>
<TD><A HREF="html/compcert.backend.ProfilingExploit.html">ProfilingExploit</A></TD>
<TD><A HREF="html/compcert.backend.ProfilingExploitproof.html">ProfilingExploitproof</A></TD>
</TR>
<TR valign="top" style="color:#000000">
<TD>FirstNop: Inserting a no-op instruction at each RTL function entrypoint</TD>
<TD>RTL to RTL</TD>
<TD><A HREF="html/compcert.backend.FirstNop.html">FirstNop</A></TD>
<TD><A HREF="html/compcert.backend.FirstNopproof.html">FirstNopproof</A></TD>
</TR>
<TR valign="top">
<TD>Postorder renumbering of the CFG (1)</TD>
<TD>RTL to RTL</TD>
<TD><A HREF="html/compcert.backend.Renumber.html">Renumber</A></TD>
<TD><A HREF="html/compcert.backend.Renumberproof.html">Renumberproof</A></TD>
</TR>
<TR valign="top">
<TD>[CSE1] Common subexpression elimination (1)</TD>
<TD>RTL to RTL</TD>
<TD><A HREF="html/compcert.backend.CSE.html">CSE</A><BR>
<A HREF="html/compcert.kvx.CombineOp.html"><I>CombineOp</I></A></TD>
<TD><A HREF="html/compcert.backend.CSEproof.html">CSEproof</A><BR>
<A HREF="html/compcert.kvx.CombineOpproof.html"><I>CombineOpproof</I></A></TD>
</TR>
<TR valign="top" style="color:#000000">
<TD colspan="4"><b>[Duplicate pass] Static Prediction + Unroll single</b></TD>
<TR valign="top" style="color:#000000">
<TD>Add static prediction information to Icond nodes<BR>
Unrolls a single iteration of innermost loops
</TD>
<TD>RTL to RTL</TD>
<TD><A HREF="html/compcert.backend.Duplicate.html">Duplicate</A> (generic checker)</TD>
<TD><A HREF="html/compcert.backend.Duplicateproof.html">Duplicateproof</A> (generic proof)<BR>
<a href="html/compcert.backend.Duplicatepasses.html">Duplicatepasses</a> (several passes from several oracles)</TD>
</TR>
<TR valign="top">
<TD>Postorder renumbering of the CFG (2)</TD>
<TD>RTL to RTL</TD>
<TD><A HREF="html/compcert.backend.Renumber.html">Renumber</A></TD>
<TD><A HREF="html/compcert.backend.Renumberproof.html">Renumberproof</A></TD>
</TR>
<TR valign="top" style="color:#000000">
<TD colspan="4"><b>[Duplicate pass] Tail Duplication</b></TD>
<TR valign="top" style="color:#000000">
<TD>Performs tail duplication on interesting traces to form superblocks
</TD>
<TD>RTL to RTL</TD>
<TD><A HREF="html/compcert.backend.Duplicate.html">Duplicate</A> (generic checker)</TD>
<TD><A HREF="html/compcert.backend.Duplicateproof.html">Duplicateproof</A> (generic proof)<BR>
<a href="html/compcert.backend.Duplicatepasses.html">Duplicatepasses</a> (several passes from several oracles)</TD>
</TR>
<TR valign="top">
<TD>Postorder renumbering of the CFG (3)</TD>
<TD>RTL to RTL</TD>
<TD><A HREF="html/compcert.backend.Renumber.html">Renumber</A></TD>
<TD><A HREF="html/compcert.backend.Renumberproof.html">Renumberproof</A></TD>
</TR>
<TR valign="top" style="color:#000000">
<TD colspan="4"><b>[Duplicate pass] Unroll body</b></TD>
<TR valign="top" style="color:#000000">
<TD>Unrolling the body of innermost loops
</TD>
<TD>RTL to RTL</TD>
<TD><A HREF="html/compcert.backend.Duplicate.html">Duplicate</A> (generic checker)</TD>
<TD><A HREF="html/compcert.backend.Duplicateproof.html">Duplicateproof</A> (generic proof)<BR>
<a href="html/compcert.backend.Duplicatepasses.html">Duplicatepasses</a> (several passes from several oracles)</TD>
</TR>
<TR valign="top">
<TD>Postorder renumbering of the CFG (4)</TD>
<TD>RTL to RTL</TD>
<TD><A HREF="html/compcert.backend.Renumber.html">Renumber</A></TD>
<TD><A HREF="html/compcert.backend.Renumberproof.html">Renumberproof</A></TD>
</TR>
<TR valign="top">
<TD>Constant propagation</TD>
<TD>RTL to RTL</TD>
<TD><A HREF="html/compcert.backend.Constprop.html">Constprop</A><br>
<A HREF="html/compcert.kvx.ConstpropOp.html"><I>ConstpropOp</I></A></TD>
<TD><A HREF="html/compcert.backend.Constpropproof.html">Constpropproof</A><br>
<A HREF="html/compcert.kvx.ConstpropOpproof.html"><I>ConstproppOproof</I></A></TD>
</TR>
<TR valign="top">
<TD>Postorder renumbering of the CFG (5)</TD>
<TD>RTL to RTL</TD>
<TD><A HREF="html/compcert.backend.Renumber.html">Renumber</A></TD>
<TD><A HREF="html/compcert.backend.Renumberproof.html">Renumberproof</A></TD>
</TR>
<TR valign="top">
<TD>[CSE1] Common subexpression elimination (1)</TD>
<TD>RTL to RTL</TD>
<TD><A HREF="html/compcert.backend.CSE.html">CSE</A><BR>
<A HREF="html/compcert.kvx.CombineOp.html"><I>CombineOp</I></A></TD>
<TD><A HREF="html/compcert.backend.CSEproof.html">CSEproof</A><BR>
<A HREF="html/compcert.kvx.CombineOpproof.html"><I>CombineOpproof</I></A></TD>
</TR>
<TR valign="top" style="color:#000000">
<TD>[CSE2] Common subexpression elimination</TD>
<TD>RTL to RTL</TD>
<TD><A HREF="html/compcert.backend.CSE2.html">CSE2</A><BR>
</TD>
<TD><A HREF="html/compcert.backend.CSE2proof.html">CSE2proof</A><BR>
</TD>
</TR>
<TR valign="top" style="color:#000000">
<TD>[CSE3] Common subexpression elimination (1)</TD>
<TD>RTL to RTL</TD>
<TD><A HREF="html/compcert.backend.CSE3.html">CSE3</A><BR>
</TD>
<TD><A HREF="html/compcert.backend.CSE3proof.html">CSE3proof</A><BR>
</TD>
</TR>
<TR valign="top" style="color:#000000">
<TD>KillUselessMoves: removing useless moves instructions after CSE3</TD>
<TD>RTL to RTL</TD>
<TD><A HREF="html/compcert.backend.KillUselessMoves.html">KillUselessMoves</A><BR>
</TD>
<TD><A HREF="html/compcert.backend.KillUselessMovesproof.html">KillUselessMovesproof</A><BR>
</TD>
</TR>
<TR valign="top" style="color:#000000">
<TD>Forwarding Moves</TD>
<TD>RTL to RTL</TD>
<TD><A HREF="html/compcert.backend.ForwardMoves.html">ForwardMoves</A><BR>
</TD>
<TD><A HREF="html/compcert.backend.ForwardMovesproof.html">ForwardMovesproof</A><BR>
</TD>
</TR>
<TR valign="top">
<TD>Redundancy elimination (1)</TD>
<TD>RTL to RTL</TD>
<TD><A HREF="html/compcert.backend.Deadcode.html">Deadcode</A></TD>
<TD><A HREF="html/compcert.backend.Deadcodeproof.html">Deadcodeproof</A></TD>
</TR>
<TR valign="top" style="color:#000000">
<TD>RTL Tunneling</TD>
<TD>RTL to RTL</TD>
<TD><A HREF="html/compcert.backend.RTLTunneling.html">RTLTunneling</A><BR>
</TD>
<TD><A HREF="html/compcert.backend.RTLTunnelingproof.html">RTLTunnelingproof</A><BR>
</TD>
</TR>
<TR valign="top">
<TD>Postorder renumbering of the CFG (6)</TD>
<TD>RTL to RTL</TD>
<TD><A HREF="html/compcert.backend.Renumber.html">Renumber</A></TD>
<TD><A HREF="html/compcert.backend.Renumberproof.html">Renumberproof</A></TD>
</TR>
<TR valign="top" style="color:#000000">
<TD colspan="4"><b>[Duplicate pass] Loop Rotate</b></TD>
<TR valign="top" style="color:#000000">
<TD>Loop rotation
</TD>
<TD>RTL to RTL</TD>
<TD><A HREF="html/compcert.backend.Duplicate.html">Duplicate</A> (generic checker)</TD>
<TD><A HREF="html/compcert.backend.Duplicateproof.html">Duplicateproof</A> (generic proof)<BR>
<a href="html/compcert.backend.Duplicatepasses.html">Duplicatepasses</a> (several passes from several oracles)</TD>
</TR>
<TR valign="top">
<TD>Postorder renumbering of the CFG (7)</TD>
<TD>RTL to RTL</TD>
<TD><A HREF="html/compcert.backend.Renumber.html">Renumber</A></TD>
<TD><A HREF="html/compcert.backend.Renumberproof.html">Renumberproof</A></TD>
</TR>
<TR valign="top" style="color:#000000">
<TD>Loop Invariant Code Motion
</TD>
<TD>RTL to RTL</TD>
<TD><A HREF="html/compcert.backend.LICM.html">LICM</A></TD>
<TD><A HREF="html/compcert.backend.LICMproof.html">LICMproof</A>
</TD>
</TR>
<TR valign="top">
<TD>Postorder renumbering of the CFG (8)</TD>
<TD>RTL to RTL</TD>
<TD><A HREF="html/compcert.backend.Renumber.html">Renumber</A></TD>
<TD><A HREF="html/compcert.backend.Renumberproof.html">Renumberproof</A></TD>
</TR>
<TR valign="top" style="color:#000000">
<TD>[CSE3] Common subexpression elimination (2)</TD>
<TD>RTL to RTL</TD>
<TD><A HREF="html/compcert.backend.CSE3.html">CSE3</A><BR>
</TD>
<TD><A HREF="html/compcert.backend.CSE3proof.html">CSE3proof</A><BR>
</TD>
</TR>
<TR valign="top">
<TD>Redundancy elimination (2)</TD>
<TD>RTL to RTL</TD>
<TD><A HREF="html/compcert.backend.Deadcode.html">Deadcode</A></TD>
<TD><A HREF="html/compcert.backend.Deadcodeproof.html">Deadcodeproof</A></TD>
</TR>
<TR valign="top" style="color:#000000">
<TD>Allnontrap: transforming loads to non-trapping ones</TD>
<TD>RTL to RTL</TD>
<TD><A HREF="html/compcert.backend.Allnontrap.html">Allnontrap</A><BR>
</TD>
<TD><A HREF="html/compcert.backend.Allnontrapproof.html">Allnontrapproof</A><BR>
</TD>
</TR>
<TR valign="top">
<TD>Removal of unused static globals</TD>
<TD>RTL to RTL</TD>
<TD><A HREF="html/compcert.backend.Unusedglob.html">Unusedglob</A></TD>
<TD><A HREF="html/compcert.backend.Unusedglobproof.html">Unusedglobproof</A></TD>
</TR>
<TR valign="top" style="color:#000000">
<TD colspan="4"><b>Passes introduced for BTL</b></TD>
</TR>
<TR valign="top" style="color:#000000">
<TD>Block selection (with Liveness information)</TD>
<TD>RTL to BTL</TD>
<TD><A HREF="html/compcert.scheduling.RTLtoBTL.html">RTLtoBTL</A></TD>
<TD><A HREF="html/compcert.scheduling.RTLtoBTLproof.html">RTLtoBTLproof</A><BR>
<A HREF="html/compcert.scheduling.BTLmatchRTL.html">BTLmatchRTL</A><BR>
<A HREF="html/compcert.scheduling.BTL_Livecheck.html">BTL_Livecheck</A>
</TD>
</TR>
<TR valign="top" style="color:#000000">
<TD>Superblock prepass scheduling</TD>
<TD>BTL to BTL</TD>
<TD><A HREF="html/compcert.scheduling.BTL_Scheduler.html">BTL_Scheduler</A></TD>
<TD><A HREF="html/compcert.scheduling.BTL_Schedulerproof.html">BTL_Schedulerproof</A><BR>
with <A HREF="html/compcert.scheduling.BTL_SEtheory.html">BTL_SEtheory</A> (the theory of symbolic execution on BTL_)<BR>
and <A HREF="html/compcert.scheduling.BTL_SEsimuref.html">BTL_SEsimuref</A> (the low-level specifications of the simulation checker)<BR>
and <A HREF="html/compcert.scheduling.BTL_SEimpl.html">BTL_SEimpl</A> (the simulation checker with hash-consing)</TD>
</TR>
<TR valign="top" style="color:#000000">
<TD>Forgeting blocks</TD>
<TD>BTL to RTL</TD>
<TD><A HREF="html/compcert.scheduling.BTLtoRTL.html">BTLtoRTL</A></TD>
<TD><A HREF="html/compcert.scheduling.BTLtoRTLproof.html">BTLtoRTLproof</A><BR>
<A HREF="html/compcert.scheduling.BTLmatchRTL.html">BTLmatchRTL</A>
</TD>
</TR>
<TR valign="top">
<TD colspan="4"><b>Passes from register allocation</b></TD>
</TR>
<TR valign="top">
<TD>Register allocation (validation a posteriori)</TD>
<TD>RTL to LTL</TD>
<TD><A HREF="html/compcert.backend.Allocation.html">Allocation</A></TD>
<TD><A HREF="html/compcert.backend.Allocationproof.html">Allocationproof</A></TD>
</TR>
<TR valign="top">
<TD>Branch tunneling</TD>
<TD>LTL to LTL</TD>
<TD><A HREF="html/compcert.backend.LTLTunneling.html">LTLTunneling</A></TD>
<TD><A HREF="html/compcert.backend.LTLTunnelingproof.html">LTLTunnelingproof</A></TD>
</TR>
<TR valign="top">
<TD>Linearization of the CFG</TD>
<TD>LTL to Linear</TD>
<TD><A HREF="html/compcert.backend.Linearize.html">Linearize</A></TD>
<TD><A HREF="html/compcert.backend.Linearizeproof.html">Linearizeproof</A></TD>
</TR>
<TR valign="top">
<TD>Removal of unreferenced labels</TD>
<TD>Linear to Linear</TD>
<TD><A HREF="html/compcert.backend.CleanupLabels.html">CleanupLabels</A></TD>
<TD><A HREF="html/compcert.backend.CleanupLabelsproof.html">CleanupLabelsproof</A></TD>
</TR>
<TR valign="top">
<TD>Synthesis of debugging information</TD>
<TD>Linear to Linear</TD>
<TD><A HREF="html/compcert.backend.Debugvar.html">Debugvar</A></TD>
<TD><A HREF="html/compcert.backend.Debugvarproof.html">Debugvarproof</A></TD>
</TR>
<TR valign="top">
<TD>Laying out the activation records</TD>
<TD>Linear to Mach</TD>
<TD><A HREF="html/compcert.backend.Stacking.html">Stacking</A><BR>
<A HREF="html/compcert.backend.Bounds.html">Bounds</A><BR>
<A HREF="html/compcert.kvx.Stacklayout.html"><I>Stacklayout</I></A></TD>
<TD><A HREF="html/compcert.backend.Stackingproof.html">Stackingproof</A><br>
<A HREF="html/compcert.common.Separation.html">Separation</A></TD>
</TR>
<TR valign="top" style="color:#000000">
<TD colspan="4"><b>Passes introduced for backends with postpass scheduling</b></TD>
</TR>
<TR valign="top" style="color:#000000">
<TD>Reconstruction of basic-blocks at Mach level</TD>
<TD>Mach to Machblock</TD>
<TD><A HREF="html/compcert.scheduling.postpass_lib.Machblockgen.html">Machblockgen</A></TD>
<TD><A HREF="html/compcert.scheduling.postpass_lib.ForwardSimulationBlock.html">ForwardSimulationBlock</A><BR>
<A HREF="html/compcert.scheduling.postpass_lib.Machblockgenproof.html">Machblockgenproof</A></TD>
</TR>
<TR valign="top" style="color:#000000">
<TD>Emission of purely sequential assembly code</TD>
<TD>Machblock to Asmblock</TD>
<TD><A HREF="html/compcert.kvx.Asmblockgen.html"><I>Asmblockgen</I></A></TD>
<TD><A HREF="html/compcert.kvx.Asmblockgenproof0.html"><I>Asmblockgenproof0</I></A><BR>
<A HREF="html/compcert.kvx.Asmblockgenproof1.html"><I>Asmblockgenproof1</I></A><BR>
<A HREF="html/compcert.kvx.Asmblockgenproof.html"><I>Asmblockgenproof</I></A></TD>
</TR>
<TR valign="top" style="color:#000000">
<TD>Bundling (and basic-block scheduling)</TD>
<TD>Asmblock to Asmvliw</TD>
<TD><A HREF="html/compcert.kvx.PostpassScheduling.html"><I>PostpassScheduling</I></A><BR>
using <A HREF="html/compcert.kvx.Asmblockdeps.html"><I>Asmblockdeps</I></A><BR>
and the <tt>abstractbb</tt> library</TD>
<TD><A HREF="html/compcert.kvx.PostpassSchedulingproof.html"><I>PostpassSchedulingproof</I></A><BR>
<A HREF="html/compcert.kvx.Asmblockprops.html"><I>Asmblockprops</I></A></TD>
</TR>
<TR valign="top" style="color:#000000">
<TD>Flattening bundles (only a bureaucratic operation)</TD>
<TD>Asmvliw to Asm</TD>
<TD><A HREF="html/compcert.kvx.Asmgen.html"><I>Asmgen</I></A></TD>
<TD><A HREF="html/compcert.kvx.Asmgenproof.html"><I>Asmgenproof</I></A> (whole simulation proof from <tt>Mach</tt> to <tt>Asm</tt>)</TD>
</TR>
</TABLE>
<H3>All together (there are many more passes than on vanilla CompCert: their order is specified in Compiler)</H3>
</font>
<font color=gray>
<UL>
<LI> <A HREF="html/compcert.driver.Compiler.html">Compiler</A>: composing the passes together;
whole-compiler semantic preservation theorems.
<LI> <A HREF="html/compcert.driver.Complements.html">Complements</A>: interesting consequences of the semantic preservation theorems.
</UL>
<H3>Static analyses</H3>
The following static analyses are performed over the RTL intermediate
representation to support optimizations such as constant propagation,
CSE, and dead code elimination.
<UL>
<LI> <A HREF="html/compcert.backend.Liveness.html">Liveness</A>: liveness analysis</A>.
<LI> <A HREF="html/compcert.backend.ValueAnalysis.html">ValueAnalysis</A>: value and alias analysis</A> <BR>
See also: <A HREF="html/compcert.backend.ValueDomain.html">ValueDomain</A>: the abstract domain for value analysis.<BR>
See also: <A HREF="html/compcert.kvx.ValueAOp.html"><I>ValueAOp</I></A>: processor-dependent parts of value analysis.
<LI> <A HREF="html/compcert.backend.Deadcode.html">Deadcode</A>: neededness analysis</A> <BR>
See also: <A HREF="html/compcert.backend.NeedDomain.html">NeedDomain</A>: the abstract domain for neededness analysis.<BR>
See also: <A HREF="html/compcert.kvx.NeedOp.html"><I>NeedOp</I></A>: processor-dependent parts of neededness analysis.
</UL>
<H3>Type systems</H3>
The <A HREF="html/compcert.cfrontend.Ctyping.html">type system of CompCert C</A> is fully formalized. For some intermediate languages of the back-end, simpler type systems are used to statically capture well-formedness conditions.
<UL>
<LI> <A HREF="html/compcert.cfrontend.Ctyping.html">Ctyping</A>: typing for CompCert C + type-checking functions.
<LI> <A HREF="html/compcert.backend.RTLtyping.html">RTLtyping</A>: typing for RTL + type
reconstruction.
<LI> <A HREF="html/compcert.backend.Lineartyping.html">Lineartyping</A>: typing for Linear.
</UL>
</font>
</BODY>
</HTML>
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