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* Improve branch tunnelingXavier Leroy2021-01-131-36/+217
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The previous branch tunneling was missing optimization opportunities introduced by the optimization of conditional branches. For example: L1: instr; branch L2 L2: if cond then branch L3 else branch L4 L3: branch L4 L4: ... was transformed into L1: instr; branch L2 L2: branch L4 L3: branch L4 L4: ... missing a tunneling opportunity (branch L2 -> branch L4). This commit improves branch tunneling so that the expected code is produced: L1: instr; branch L4 L2: branch L4 L3: branch L4 L4: ... To this end, additional equalities are introduced in the union-find data structure corresponding to optimizable conditional branches. In rare cases these additional equalities trigger new opportunities for optimizing conditional branches. Hence we iterate the analysis until no optimizable conditional branch remains.
* Revised correctness proof for record_gotoXavier Leroy2021-01-131-68/+29
| | | | | | | | | | We used to define an instrumented version record_goto' that also builds the measure f, prove it correct, then show equivalence with record_goto. The new proofs make do without the instrumented version. They prove strong existence of the measure, as in `{ f | branch_map_correct (record_goto fn) f}`.
* Replace `omega` tactic with `lia`Xavier Leroy2020-12-291-4/+4
| | | | | | | | | | | Since Coq 8.12, `omega` is flagged as deprecated and scheduled for removal. Also replace CompCert's homemade tactics `omegaContradiction`, `xomega`, and `xomegaContradiction` with `lia` and `extlia`. Turn back on the deprecation warning for uses of `omega`. Make the proof of `Ctypes.sizeof_pos` more robust to variations in `lia`.
* Treat Outgoing stack slots as caller-save in LTL/Linear semantics (#237)Xavier Leroy2018-06-171-2/+4
| | | | | | | | | | | | | | | | | | | * Outgoing stack slots are set to Vundef on return from a function call, modeling the fact that the callee could write into those stack slots. (CompCert-generated code does not do this, but code generated by other compilers sometimes does.) * Adapt Stackingproof to this new semantics. This requires tighter reasoning on how Linear's locsets are related at call points and at return points. * Most of this reasoning was moved from Stackingproof to Lineartyping, because it can be expressed purely in terms of the Linear semantics, and tracked through the wt_state predicate. * Factor out and into Conventions.v: the notion of callee-save locations, the "agree_callee_save" predicate, and useful lemmas on Locmap.setpair. Now the same "agree_callee_save" predicate is used in Allocproof and in Stackingproof.
* Model external calls as destroying all caller-save registersXavier Leroy2018-06-011-1/+9
| | | | | | | | | | The semantics of external function calls in LTL, Linear, Mach and Asm now consider that all caller-save registers are set to Vundef by the call. This models that fact that the external function can modify those registers arbitrarily. Update the proofs of the Allocation, Tunneling, Stacking and Asmgen passes accordingly.
* Remove coq warnings (#28)Bernhard Schommer2017-09-221-1/+1
| | | | Replace deprecated functions and theorems from the Coq standard library (version 8.6) by their non-deprecated counterparts.
* Tunnelingproof: Remove assumption destroyed_by_cond c = nil.Xavier Leroy2017-05-021-66/+210
| | | | Since commit e5b37a6 (useless conditional branch elimination), the proof of the Tunneling pass was assuming forall c, destroyed_by_cond c = nil. This is not true for architecture variants that we will support soon. This commit rewrites the proof so as to remove this assumption. The old proof was by memory and value equalities, the new one is by memory extensions and "lessdef" values.
* Another optimization of empty if/else and other useless conditional branchesXavier Leroy2017-04-061-29/+36
| | | | | | | | | | This commit eliminates useless conditional branches during the branch tunneling pass over LTL. Conditional branches where both successors go to the same LTL node are turned into unconditional branches, which will stay or be eliminated by the subsequent Linear pass. One code pattern that triggers this optimization is an empty if/else at the C source level. Commit 4d7a459 eliminates these empty if/else statements early, during the Compcert C -> Clight translation. I think it's good to have both optimizations: - Early elimination makes sure these empty if/else cause no overhead whatsoever, and in particular cannot degrade the precision of later static analyses. - Late elimination catches the case where a nonempty if/else in the source becomes empty as a consequence of optimizations. Future work? If the optimization in Tunneling triggers, it might be worth re-running the Tunneling pass once more, to make sure that the "Lgoto" introduced by the optimization is properly tunneled / skipped over when appropriate.
* Introduce register pairs to describe calling conventions more preciselyXavier Leroy2016-05-171-2/+2
| | | | | | | | | | | | | This commit changes the loc_arguments and loc_result functions that describe calling conventions so that each argument/result can be mapped either to a single location or (in the case of a 64-bit integer) to a pair of two 32-bit locations. In the current CompCert, all arguments/results of type Tlong are systematically split in two 32-bit halves. We will need to change this in the future to support 64-bit processors. The alternative approach implemented by this commit enables the loc_arguments and loc_result functions to describe precisely which arguments need splitting. Eventually, the remainder of CompCert should not assume anything about splitting 64-bit types in two halves. Summary of changes: - AST: introduce the type "rpair A" of register pairs - Conventions1, Conventions: use it when describing calling conventions - LTL, Linear, Mach, Asm: honor the new calling conventions when observing external calls - Events: suppress external_call', no longer useful - All passes from Allocation to Asmgen: adapt accordingly.
* Update the back-end proofs to the new linking framework.Xavier Leroy2016-03-061-32/+26
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* Updated PR by removing whitespaces. Bug 17450.Bernhard Schommer2015-10-201-33/+33
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* Refactoring of builtins and annotations in the back-end.Xavier Leroy2015-08-211-8/+2
| | | | | | | | | | | | | | | | | | | | | | | | Before, the back-end languages had distinct instructions - Iannot for annotations, taking structured expressions (annot_arg) as arguments, and producing no results' - Ibuiltin for other builtins, using simple pseudoregs/locations/registers as arguments and results. This branch enriches Ibuiltin instructions so that they take structured expressions (builtin_arg and builtin_res) as arguments and results. This way, - Annotations fit the general pattern of builtin functions, so Iannot instructions are removed. - EF_vload_global and EF_vstore_global become useless, as the same optimization can be achieved by EF_vload/vstore taking a structured argument of the "address of global" kind. - Better code can be generated for builtin_memcpy between stack locations, or volatile accesses to stack locations. Finally, this commit also introduces a new kind of external function, EF_debug, which is like EF_annot but produces no observable events. It will be used later to transport debug info through the back-end, without preventing optimizations.
* Extend annotations so that they can keep track of global variables and local ↵Xavier Leroy2015-03-271-2/+3
| | | | | | | | | | variables whose address is taken. - CminorSel, RTL: add "annot" instructions. - CminorSel to Asm: use type "annot_arg" for arguments of "annot" instructions. - AST, Events: simplify EF_annot because constants are now part of the arguments. Implementation is not complete yet.
* Add Genv.public_symbol operation.Xavier Leroy2014-11-241-4/+9
| | | | | Restrict pointer event values to public global names. Update proofs accordingly. PowerPC and ARM need updating.
* Big merge of the newregalloc-int64 branch. Lots of changes in two directions:xleroy2013-04-201-82/+112
| | | | | | | | | 1- new register allocator (+ live range splitting, spilling&reloading, etc) based on a posteriori validation using the Rideau-Leroy algorithm 2- support for 64-bit integer arithmetic (type "long long"). git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@2200 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Merge of the nonstrict-ops branch:xleroy2012-01-141-7/+2
| | | | | | | | | | | - Most RTL operators now evaluate to Some Vundef instead of None when undefined behavior occurs. - More aggressive instruction selection. - "Bertotization" of pattern-matchings now implemented by a proper preprocessor. - Cast optimization moved to cfrontend/Cminorgen; removed backend/CastOptim. git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1790 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Merge of branch new-semantics: revised and strengthened top-level statements ↵xleroy2011-07-151-15/+14
| | | | | | of semantic preservation. git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1683 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Support for inlined built-ins.xleroy2010-06-291-0/+8
| | | | | | | | | | | | | AST: add ef_inline flag to external functions. Selection: recognize calls to inlined built-ins and inline them as Sbuiltin. CminorSel to Asm: added Sbuiltin/Ibuiltin instruction. PrintAsm: adapted expansion of builtins. C2Clight: adapted detection of builtins. Conventions: refactored in a machine-independent part (backend/Conventions) and a machine-dependent part (ARCH/SYS/Conventions1). git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1356 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* More faithful semantics for volatile reads and writes.xleroy2010-05-231-1/+6
| | | | git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1346 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* - Extended traces so that pointers within globals are supported as event values.xleroy2010-05-101-0/+1
| | | | | | | | - Revised handling of volatile reads: the execution environment dictates the value read, via the trace of events. git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1345 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Merge of the newmem and newextcalls branches:xleroy2010-03-071-6/+5
| | | | | | | | | | - Revised memory model with concrete representation of ints & floats, and per-byte access permissions - Revised Globalenvs implementation - Matching changes in all languages and proofs. git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1282 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Added support for jump tables in back end.xleroy2009-11-101-0/+7
| | | | git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1171 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Added 'going wrong' behaviorsxleroy2009-08-051-108/+113
| | | | git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1120 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Adapted to work with Coq 8.2-1v1.4.1xleroy2009-06-051-2/+4
| | | | git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1076 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* - Added alignment constraints to memory loads and stores.xleroy2009-01-111-6/+0
| | | | | | | | | | | - In Cminor and below, removed pointer validity check in semantics of comparisons, so that evaluation of expressions is independent of memory state. - In Cminor and below, removed "alloc" instruction. - Cleaned up commented-away parts. git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@945 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* MAJ documentationxleroy2008-07-271-1/+1
| | | | git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@702 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Simplification de la semantique de LTL et LTLin. Les details lies aux ↵xleroy2008-07-251-20/+9
| | | | | | conventions d'appel sont maintenant geres de maniere plus locale dans la passe Reload. git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@701 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Nettoyage du traitement des signatures au return dans LTL et LTLinxleroy2008-07-071-9/+9
| | | | git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@690 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Ajout license, README, copyright noticesxleroy2008-01-271-0/+12
| | | | git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@489 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Fusion des modifications faites sur les branches "tailcalls" et "smallstep".xleroy2007-08-041-212/+260
| | | | | | | | | | | | En particulier: - Semantiques small-step depuis RTL jusqu'a PPC - Cminor independant du processeur - Ajout passes Selection et Reload - Ajout des langages intermediaires CminorSel et LTLin correspondants - Ajout des tailcalls depuis Cminor jusqu'a PPC git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@384 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Revu traitement des variables globales dans AST.program et dans Globalenvs.xleroy2006-09-051-3/+3
| | | | | | | | Adaptation frontend, backend en consequence. Integration passe C -> C#minor dans common/Main.v. git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@77 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Fusion de la branche "traces":xleroy2006-09-041-62/+74
| | | | | | | | | | | | | - Ajout de traces d'evenements d'E/S dans les semantiques - Ajout constructions switch et allocation dynamique - Initialisation des variables globales - Portage Coq 8.1 beta Debut d'integration du front-end C: - Traduction Clight -> Csharpminor dans cfrontend/ - Modifications de Csharpminor et Globalenvs en consequence. git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@72 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Initial import of compcertxleroy2006-02-091-0/+311
git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
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