aboutsummaryrefslogtreecommitdiffstats
path: root/cfrontend/Csem.v
Commit message (Collapse)AuthorAgeFilesLines
* Native support for bit fields (#400)Xavier Leroy2021-08-221-46/+60
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This big PR adds support for bit fields in structs and unions to the verified part of CompCert, namely the CompCert C and Clight languages. The compilation of bit field accesses to normal integer accesses + shifts and masks is done and proved correct as part of the Cshmgen pass. The layout of bit fields in memory is done by the functions in module Ctypes. It follows the ELF ABI layout algorithm. As a bonus, basic soundness properties of the layout are shown, such as "two different bit fields do not overlap" or "a bit field and a regular field do not overlap". All this replaces the previous emulation of bit fields by source-to-source rewriting in the unverified front-end of CompCert (module cparse/Bitfield.ml). This emulation was prone to errors (see nonstandard layout instead. The core idea for the PR is that expressions in l-value position denote not just a block, a byte offset and a type, but also a bitfield designator saying whether all the bits of the type are accessed (designator Full) or only some of its bits (designator Bits). Designators of the Bits kind appear when the l-value is a bit field access; the bit width and bit offset in Bits are computed by the functions in Ctypes that implement the layout algorithm. Consequently, both in the semantics of CompCert C and Clight and in the SimplExpr, SimplLocals and Cshmgen compilation passes, pairs of a type and a bitfield designator are used in a number of places where a single type was used before. The introduction of bit fields has a big impact on static initialization (module cfrontend/Initializers.v), which had to be rewritten in large part, along with its soundness proof (cfrontend/Initializersproof.v). Both static initialization and run-time manipulation of bit fields are tested in test/abi using differential testing against GCC and randomly-generated structs. This work exposed subtle interactions between bit fields and the volatile modifier. Currently, the volatile modifier is ignored when accessing a bit field (and a warning is printed at compile-time), just like it is ignored when accessing a struct or union as a r-value. Currently, the natural alignment of bit fields and their storage units cannot be modified with the aligned attribute. _Alignas on bit fields is rejected as per C11, and the packed modifier cannot be applied to a struct containing bit fields.
* Use the LGPL instead of the GPL for dual-licensed filesXavier Leroy2021-05-081-4/+5
| | | | | | The GPL makes sense for whole applications, but the dual-licensed Coq and OCaml files are more like libraries to be combined with other code, so the LGPL is more appropriate.
* 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`.
* Refine the type of function results in AST.signatureXavier Leroy2020-02-211-1/+1
| | | | | | | | | | Before it was "option typ". Now it is a proper inductive type that can also express small integer types (8/16-bit unsigned/signed integers). One benefit is that external functions get more precise types that control better their return values. As a consequence, the CompCert C type preservation property now holds unconditionally, without extra typing hypotheses on external functions.
* Make __builtin_sel available from C source codeXavier Leroy2019-07-171-13/+56
| | | | | It is type-checked like a conditional expression then translated to a call to the known builtin function.
* Support for 64-bit architectures: generic supportXavier Leroy2016-10-011-15/+15
| | | | | | | | | | | - Introduce Archi.ptr64 parameter. - Define module Ptrofs of integers as wide as a pointer (64 if Archi.ptr64, 32 otherwise). - Use Ptrofs.int as the offset type for Vptr values and anywhere pointer offsets are manipulated. - Modify Val operations that handle pointers (e.g. Val.add, Val.sub, Val.cmpu) so that in 64-bit pointer mode it is the "long" operation (e.g. Val.addl, Val.subl, Val.cmplu) that handles pointers. - Update the memory model accordingly. - Modify C operations that handle pointers (e.g. addition, subtraction, comparisons) accordingly. - Make it possible to turn off the splitting of 64-bit integers into pairs of 32-bit integers. - Update the compiler front-end and back-end accordingly.
* Make casts of pointers to _Bool semantically well defined (again).Xavier Leroy2016-03-021-20/+17
| | | | | | In compCert 2.5 the semantics of pointer comparisons against the NULL pointer was made more accurate by making it undefined if the pointer is invalid (outside bounds). Technical difficulties prevented this change from being propagated to the semantics of casts from pointer types to the _Bool type, which involves an implicit pointer comparison against NULL. Hence, this kind of casts was temporarily given undefined semantics. This commit makes pointer-to-_Bool casts semantically defined (again), provided the pointer is valid. This reinstates the equivalence between casts to _Bool and comparisons != 0. The technical difficulties mentioned above came from the translation of assignments in a value context in the SimplExpr pass. The pass was lightly modified to work around the issue.
* Updated PR by removing whitespaces. Bug 17450.Bernhard Schommer2015-10-201-9/+9
|
* Omission: forgot to treat pointer values in bool_of_val and sem_notbool.Xavier Leroy2015-03-291-13/+13
|
* Interpreter produces more detailed trace, including name of semantic rules used.Xavier Leroy2015-02-081-1/+1
| | | | | | Cexec: record names of rules used in every reduction. Interp: print these rule names in -trace mode. Also: simplified the exploration in "-all" mode; give unique names to states. Csem: fix name of reduction rule "red_call".
* Represent struct and union types by name instead of by structure.Xavier Leroy2014-12-221-44/+52
|
* Revised translation of '&&' and '||' to Clight.Xavier Leroy2014-10-131-8/+8
| | | | | | | | | | | The previous translation (in SimplExpr) produced references to the same temporary variable with two different types (bool and int), which is not nice if we want to typecheck the generated Clight. The new translation avoids this and also gets rid of the double cast to bool then to int. The trick is to change Eparen (in CompCert C expressions) to take two types: the type to which the argument must be converted, and the type with which the resulting expression is seen.
* - Support "switch" statements over 64-bit integersxleroy2014-08-171-5/+6
| | | | | | | | | | | | | (in CompCert C to Cminor, included) - Translation of "switch" to decision trees or jumptables made generic over the sizes of integers and moved to the Cminor->CminorSel pass instead of CminorSel->RTL as before. - CminorSel: add "exitexpr" to support the above. - ValueDomain: more precise analysis of comparisons against an integer literal. E.g. "x >=u 0" is always true. git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@2565 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Use "incrdecr_type ty" instead of "typeconv ty" as the intermediate typexleroy2014-04-151-1/+3
| | | | | | | for Epostincr operations. git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@2455 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Remove useless checks on type_of_global in dynamic semanticsxleroy2014-02-201-14/+0
| | | | git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@2411 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Simpler, more robust emulation of calls to variadic functions:xleroy2013-12-281-6/+6
| | | | | | | | | | | | | | - C function types and Cminor signatures annotated by calling conventions. esp. vararg / not vararg - Cshmgen: generate correct code for function call where there are more arguments than listed in the function prototype. This is still undefined behavior according to the formal semantics, but correct code is generated. - C2C, */PrintAsm.ml: remove "printf$iif" hack. - powerpc/, checklink/: don't generate stubs for variadic functions. git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@2386 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Support "default" cases in the middle of a "switch", not just at the end.xleroy2013-12-211-8/+21
| | | | git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@2383 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Merge of the "alignas" branch.xleroy2013-10-051-1/+2
| | | | git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@2342 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Merge of the clightgen branch:xleroy2012-12-291-1/+0
| | | | | | | | | | | | | | | | | | - Alternate semantics for Clight where function parameters are temporaries, not variables - New pass SimplLocals that turns non-addressed local variables into temporaries - Simplified Csharpminor, Cshmgen and Cminorgen accordingly - SimplExpr starts its temporaries above variable names, therefoe Cminorgen no longer needs to encode variable names and temps names. - Simplified Cminor parser & printer, as well as Errors, accordingly. - New tool clightgen to produce Clight AST in Coq-parsable .v files. - Removed side condition "return type is void" on rules skip_seq in the semantics of CompCert C, Clight, C#minor, Cminor. - Adapted RTLgenproof accordingly (now uses a memory extension). git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@2083 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Make Clight independent of CompCert C.xleroy2012-10-081-519/+2
| | | | | | | Common parts are factored out in cfrontend/Ctypes.v and cfrontend/Cop.v git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@2060 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Merge of branch seq-and-or. See Changelog for details.xleroy2012-10-061-39/+95
| | | | git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@2059 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Make min_int / -1 and min_int % -1 semantically undefinedxleroy2012-06-091-2/+6
| | | | git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1919 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* - Support for _Alignof(ty) operator from ISO C 2011xleroy2012-02-261-0/+3
| | | | | | | | | | and __alignof__(ty), __alignof__(expr) from GCC. - Resurrected __builtin_memcpy_aligned, useful for files generated by Scade KCG 6. git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1827 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Merge of the "volatile" branch:xleroy2012-02-041-91/+180
| | | | | | | | | | | | - native treatment of volatile accesses in CompCert C's semantics - translation of volatile accesses to built-ins in SimplExpr - native treatment of struct assignment and passing struct parameter by value - only passing struct result by value remains emulated - in cparser, remove emulations that are no longer used - added C99's type _Bool and used it to express || and && more efficiently. git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1814 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Cleaned up old commented-out partsxleroy2011-08-191-34/+0
| | | | git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1719 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Improved semantics of castsxleroy2011-07-171-0/+39
| | | | git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1685 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* In conditional expressions e1 ? e2 : e3, cast the results of e2 and e3 to ↵xleroy2011-07-161-127/+96
| | | | | | | | | the type of the whole conditional expression. Replaced predicates "cast", "is_true" and "is_false" by functions "sem_cast" and "bool_val". git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1684 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Merge of branch new-semantics: revised and strengthened top-level statements ↵xleroy2011-07-151-6/+3
| | | | | | of semantic preservation. git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1683 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Fix treatment of function pointers at function calls in the CompCert C and ↵xleroy2011-07-141-2/+3
| | | | | | Clight semantics git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1680 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Merge of branch "unsigned-offsets":xleroy2011-04-091-6/+11
| | | | | | | | | | | | | | - In pointer values "Vptr b ofs", interpret "ofs" as an unsigned int. (Fixes issue with wrong comparison of pointers across 0x8000_0000) - Revised Stacking pass to not use negative SP offsets. - Add pointer validity checks to Cminor ... Mach to support the use of memory injections in Stacking. - Cleaned up Stacklayout modules. - IA32: improved code generation for Mgetparam. - ARM: improved code generation for op-immediate instructions. git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1632 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Initializers for global variables: compile-time evaluation of expressions ↵xleroy2011-03-121-1/+1
| | | | | | done in Coq (module Initializers), using the same primitives as those for CompCert C's semantics. git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1602 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Float.intoffloat and Float.intuoffloat are now partial functions.xleroy2010-10-281-3/+4
| | | | | | | (May fail if float is too big to be converted.) git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1544 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Nettoyages pour docxleroy2010-08-181-2/+2
| | | | git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1471 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Removed useless constraints on return type at Sreturn instructionsxleroy2010-08-181-2/+0
| | | | git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1470 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Merge of branches/full-expr-4:xleroy2010-08-181-1176/+617
| | | | | | | | | | | | | | | | | | | | | | - Csyntax, Csem: source C language has side-effects within expressions, performs implicit casts, and has nondeterministic reduction semantics for expressions - Cstrategy: deterministic red. sem. for the above - Clight: the previous source C language, with pure expressions. Added: temporary variables + implicit casts. - New pass SimplExpr to pull side-effects out of expressions (previously done in untrusted Caml code in cparser/) - Csharpminor: added temporary variables to match Clight. - Cminorgen: adapted, removed cast optimization (moved to back-end) - CastOptim: RTL-level optimization of casts - cparser: transformations Bitfields, StructByValue and StructAssign now work on non-simplified expressions - Added pretty-printers for several intermediate languages, and matching -dxxx command-line flags. git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1467 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Support for inlined built-ins.xleroy2010-06-291-6/+6
| | | | | | | | | | | | | 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.xleroy2010-05-231-2/+2
| | | | 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.xleroy2010-05-101-2/+2
| | | | | | | | - 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
* Suppressed axioms Float.eq_zero_{true,false}, since the latter isxleroy2010-05-091-3/+4
| | | | | | | | | | wrong because of +0.0 / -0.0. Adapted Clight semantics accordingly. (Truth value of a float is defined by comparison Float.cmp Ceq with 0.0, no longer by structural equality.) git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1342 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Add "fabs" (floating-point absolute value) as a unary operator inxleroy2010-05-021-0/+7
| | | | | | | Clight and C#minor. Recognize __builtin_fabs and turn it into this operator. git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1329 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Merge of the newmem and newextcalls branches:xleroy2010-03-071-39/+46
| | | | | | | | | | - 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
* Function types didn't always degrade to pointers like they should. ↵xleroy2010-03-021-1/+1
| | | | | | Introduced and used Csyntax.typeconv to address this issue and reduce the number of cases in the classify functions git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1266 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Revised lib/Integers.v to make it parametric w.r.t. word size.xleroy2009-11-191-3/+3
| | | | | | | | | Introduced Int.iwordsize and used it in place of "Int.repr 32" or "Int.repr (Z_of_nat wordsize)". git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1182 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Last updates for release 1.5.v1.5xleroy2009-08-281-9/+9
| | | | git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1142 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Distinguish two kinds of nonterminating behaviors: silent divergencexleroy2009-08-161-25/+31
| | | | | | | | | | | | | | and reactive divergence. As a consequence: - Removed the Enilinf constructor from traceinf (values of traceinf type are always infinite traces). - Traces are now uniquely defined. - Adapted proofs big step -> small step for Clight and Cminor accordingly. - Strengthened results in driver/Complements accordingly. - Added common/Determinism to collect generic results about deterministic semantics. git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1123 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Transition semantics for Clight and Csharpminorxleroy2009-08-031-99/+876
| | | | git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1119 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Adapted to work with Coq 8.2-1v1.4.1xleroy2009-06-051-1/+1
| | | | git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1076 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Replace cast{8,16}{signed,unsigned} with zero_ext and sign_ext.xleroy2008-12-291-4/+4
| | | | | | | | lib/Integers.v: added more properties for ARM port. lib/Coqlib.v: added more properties for division and powers of 2. git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@928 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Clight: ajout Econdition, suppression Eindex.xleroy2008-09-271-5/+10
| | | | | | | | caml/PrintCsyntax.ml: afficher les formes a[b] et a->fld. git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@789 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Utilisation de intoffloatu. Ajout du cas int + ptr.xleroy2008-05-311-10/+22
| | | | git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@652 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
generated by cgit (git 2.34.1) at 2024-05-19 21:55:44 +0000