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* Native support for bit fields (#400)Xavier Leroy2021-08-221-47/+281
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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.
* 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.
* Initializers: introduce 'constval_cast' to cast constant value to desired typeXavier Leroy2016-11-171-3/+7
| | | | This comes handy in the next commit where constval_cast is used from C2C.
* Regression: compile-time evaluation of ((struct s *)0)->fieldXavier Leroy2016-10-061-1/+3
| | | | | This somewhat useful idiom was broken when Val.add was replaced by Val.offset_ptr in the Efield case. This commit restores the previous behavior. This used to be supported (and is useful
* Support for 64-bit architectures: generic supportXavier Leroy2016-10-011-19/+12
| | | | | | | | | | | - 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 Leroy2016-03-021-1/+1
| | | | | | 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.
* Handle large static initializers for global arraysXavier Leroy2015-11-091-21/+26
| | | | Use tail-recursive operations to implement transformations on initializers for global arrays. This way, very large static initializers no longer cause stack overflows at compile-time.
* Omission: forgot to treat pointer values in bool_of_val and sem_notbool.Xavier Leroy2015-03-291-4/+4
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* Represent struct and union types by name instead of by structure.Xavier Leroy2014-12-221-50/+65
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* Revised translation of '&&' and '||' to Clight.Xavier Leroy2014-10-131-4/+4
| | | | | | | | | | | 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.
* Merge of "newspilling" branch:xleroy2014-07-231-2/+2
| | | | | | | | | | | | | | | - Support single-precision floats as first-class values - Introduce chunks Many32, Many64 and types Tany32, Tany64 to support saving and restoring registers without knowing the exact types (int/single/float) of their contents, just their sizes. - Memory model: generalize the opaque encoding of pointers to apply to any value, not just pointers, if chunks Many32/Many64 are selected. - More properties of FP arithmetic proved. git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@2537 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* C: Support array initializers that are too short + default init for remainder.xleroy2014-03-281-17/+9
| | | | | | | | Elab: Handle C99 designated initializers. C2C, Initializers: more precise intermediate AST for initializers. git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@2439 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Support array initialization lists that are too shortxleroy2014-03-181-2/+2
| | | | git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@2432 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Ctypes.sizeof ty = 0 for empty types ty (zero-sized array, empty struct/union).xleroy2013-12-301-6/+1
| | | | | | | __builtin_memcpy_aligned now supports the case sz = 0. git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@2392 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Revised treatment of _Alignas, for better compatibility with GCC and Clang, ↵xleroy2013-11-061-9/+5
| | | | | | and to avoid wasting global variable space by inflating their sizeof needlessly. git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@2362 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Merge of the "alignas" branch.xleroy2013-10-051-4/+9
| | | | git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@2342 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Merge of the "princeton" branch:xleroy2013-06-161-5/+5
| | | | | | | | | | | | | | - Define type "block" as "positive" instead of "Z". - Strengthen mem_unchanged_on so that the permissions are identical, instead of possibly increasing. - Move mem_unchanged_on from Events to Memory.Mem. - Define it in terms of mem_contents rather than in terms of Mem.load. - ExportClight: try to name temporaries introduced by SimplExpr - SimplExpr: avoid reusing temporaries between different functions, instead, thread a single generator through all functions. git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@2276 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Missing case: initialization of a global variable of type _Bool.xleroy2013-05-081-1/+1
| | | | | | | Added corresponding test case. git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@2242 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Big merge of the newregalloc-int64 branch. Lots of changes in two directions:xleroy2013-04-201-1/+2
| | | | | | | | | 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
* Watch out for behaviors exponential in the nesting of struct/union types. xleroy2013-03-231-2/+4
| | | | git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@2158 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Remove some useless "Require".xleroy2012-12-301-1/+0
| | | | | | | Update ARM port. git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@2085 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Make Clight independent of CompCert C.xleroy2012-10-081-0/+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.xleroy2012-10-061-0/+16
| | | | git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@2059 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* - Support for _Alignof(ty) operator from ISO C 2011xleroy2012-02-261-0/+2
| | | | | | | | | | 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
* Initializers: handle By_copy accesses (e.g. for &(glob.field))xleroy2012-02-071-2/+2
| | | | | | | | | C2C: insert the correct Evalof for structs; clean up unused memcpy stuff test/regression: run with interpreter test/regression: add test cas &(glob.field) to initializers.c git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1815 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Merge of the "volatile" branch:xleroy2012-02-041-15/+15
| | | | | | | | | | | | - 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
* In conditional expressions e1 ? e2 : e3, cast the results of e2 and e3 to ↵xleroy2011-07-161-48/+13
| | | | | | | | | 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
* More global initialization work done and proved in Coq.xleroy2011-03-131-3/+74
| | | | git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@1603 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
* Initializers for global variables: compile-time evaluation of expressions ↵xleroy2011-03-121-0/+173
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
generated by cgit (git 2.34.1) at 2024-05-19 22:11:14 +0000