CompCert is a compiler that generates ARM, PowerPC, 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.
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):
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 italics 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.
This development is a work in progress; some parts have substantially changed since the overview papers above were written.
The complete sources for CompCert can be downloaded from the Git repository or the CompCert Web site.
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 license.
| Pass | Source & target | Compiler code | Correctness proof |
|---|---|---|---|
| Pulling side-effects out of expressions; fixing an evaluation order |
CompCert C to Clight | SimplExpr | SimplExprspec SimplExprproof |
| Pulling non-adressable scalar local variables out of memory | Clight to Clight | SimplLocals | SimplLocalsproof |
| Simplification of control structures; explication of type-dependent computations |
Clight to Csharpminor | Cshmgen | Cshmgenproof |
| Stack allocation of local variables whose address is taken; simplification of switch statements |
Csharpminor to Cminor | Cminorgen | Cminorgenproof |
| Recognition of operators and addressing modes; if-conversion |
Cminor to CminorSel | Selection SelectOp SelectLong SelectDiv SplitLong |
Selectionproof SelectOpproof SelectLongproof SelectDivproof SplitLongproof |
| Construction of the CFG; 3-address code generation | CminorSel to RTL | RTLgen | RTLgenspec RTLgenproof |
| Recognition of tail calls | RTL to RTL | Tailcall | Tailcallproof |
| Function inlining | RTL to RTL | Inlining | Inliningspec Inliningproof |
| Postorder renumbering of the CFG | RTL to RTL | Renumber | Renumberproof |
| Constant propagation | RTL to RTL | Constprop ConstpropOp |
Constpropproof ConstproppOproof |
| Common subexpression elimination | RTL to RTL | CSE CombineOp |
CSEproof CombineOpproof |
| Redundancy elimination | RTL to RTL | Deadcode | Deadcodeproof |
| Removal of unused static globals | RTL to RTL | Unusedglob | Unusedglobproof |
| Register allocation (validation a posteriori) | RTL to LTL | Allocation | Allocproof |
| Branch tunneling | LTL to LTL | Tunneling | Tunnelingproof |
| Linearization of the CFG | LTL to Linear | Linearize | Linearizeproof |
| Removal of unreferenced labels | Linear to Linear | CleanupLabels | CleanupLabelsproof |
| Synthesis of debugging information | Linear to Linear | Debugvar | Debugvarproof |
| Laying out the activation records | Linear to Mach | Stacking Bounds Stacklayout |
Stackingproof Separation |
| Emission of assembly code | Mach to Asm | Asmgen | Asmgenproof0 Asmgenproof1 Asmgenproof |