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* Merge branch 'master' into merge_master_8.13.1Sylvain Boulmé2021-03-231-3/+3
|\ | | | | | | | | | | | | | | | | PARTIAL MERGE (PARTLY BROKEN). See unsolved conflicts in: aarch64/TO_MERGE and riscV/TO_MERGE WARNING: interface of va_args and assembly sections have changed
| * Improve branch tunnelingXavier Leroy2021-01-131-24/+111
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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.
* | minor fix in coq2html commentSylvain Boulmé2020-11-161-1/+2
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* | Tunneling: improved elimination of conditionsSylvain Boulmé2020-11-161-37/+98
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Previously, the elimination of useless conditions done in the 2nd pass of the tunneling introduced some new "nop" instructions that were not eliminated. This commit solves this issue by anticipating the elimination of conditions in the 1st pass of the tunneling, the 2nd pass being unchanged. In case of cycles in the CFG, the full elimination of useless conditions may require several iterations in the 1st pass. Moreover, in the simulation proof, the measure counting the number of eliminated steps from each node, needs to be adapted according to the modifications on the 1st pass. Hence, this measure results from a quite complex fixpoint computation: proving its properties would be very difficult. This leads us to introduce an oracle, implementing the first pass and producing the expected measure. A certified verifier directly checks that the measure provided by the oracle satisfies the properties expected by the simulation proof. Introducing this oracle/verifier pair has here the following advantage: - the proof is simpler than the original one (e.g. having a certified union-find structure is no more necessary for this pass). - the oracle is very efficient, by using imperative data-structure to compute memoized fixpoints. At runtime, the overhead induced by the verifier computations (and the actual computation of the measure) seems largely compensated by the gains obtained through the imperative oracle.
* | automated writing Compiler.vDavid Monniaux2020-04-221-1/+1
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* | Adding info field for branching in RTL, LTL, XTL and all associated passesCyril SIX2020-03-111-2/+2
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* Another optimization of empty if/else and other useless conditional branchesXavier Leroy2017-04-061-2/+5
| | | | | | | | | | 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.
* Update the back-end proofs to the new linking framework.Xavier Leroy2016-03-061-3/+1
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* Updated PR by removing whitespaces. Bug 17450.Bernhard Schommer2015-10-201-1/+1
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* Big merge of the newregalloc-int64 branch. Lots of changes in two directions:xleroy2013-04-201-27/+13
| | | | | | | | | 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
* Remove some useless "Require".xleroy2012-12-301-4/+0
| | | | | | | Update ARM port. git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@2085 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Updated documentationxleroy2012-08-021-28/+19
| | | | git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1989 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Support for inlined built-ins.xleroy2010-06-291-0/+2
| | | | | | | | | | | | | 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
* Added support for jump tables in back end.xleroy2009-11-101-0/+2
| | | | git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1171 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Cil2Csyntax: added goto and labels; added assignment between structsxleroy2009-08-161-13/+1
| | | | | | | | | | | | Kildall: simplified the interface Constprop, CSE, Allocation, Linearize: updated for the new Kildall RTL, LTL: removed the well-formedness condition on the CFG, it is no longer necessary with the new Kildall and it is problematic for validated optimizations. Maps: more efficient implementation of PTree.fold. git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1124 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Added 'going wrong' behaviorsxleroy2009-08-051-29/+22
| | | | git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1120 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* - Added alignment constraints to memory loads and stores.xleroy2009-01-111-2/+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
* 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".xleroy2007-08-041-28/+28
| | | | | | | | | | | | 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
* Fusion de la branche "traces":xleroy2006-09-041-1/+6
| | | | | | | | | | | | | - 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/+131
git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
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