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* Update the RISC-V calling conventions, continued (#227)Xavier Leroy2020-03-021-7/+10
| | | | | | | | Double FP arguments passed on stack were incorrectly aligned: they must be 8-aligned but were 4-aligned only. This was due to the use of `Location.typealign`, which is the minimal hardware-supported alignment for a given type, namely 1 word for type Tfloat. To get the correct alignments, `Location.typesize` must be used instead.
* Update the RISC-V calling conventions (#221)Xavier Leroy2020-02-261-119/+131
| | | | | | | | | | | | We were implementing the ABI described in the RISC-V Instruction Set Manual, version 2.1. However, this ABI was superseded by the RISC-V ELF psABI specification. This commit changes the calling conventions to better match the ELF psABI specification. This should greatly improve interoperability with code compiled by other RISC-V compilers. One incompatibility remains: when all 8 FP argument registers have been used, further FP arguments should be passed in integer argument registers if available, while this PR passes them on stack.
* Platform-independent implementation of Conventions.size_arguments (#222)Xavier Leroy2020-02-241-64/+0
| | | | | | | | | | | | | | The "size_arguments" function and its properties can be systematically derived from the "loc_arguments" function and its properties. Before, the RISC-V port used this derivation, and all other ports used hand-written "size_arguments" functions and proofs. This commit moves the definition of "size_arguments" to the platform-independent file backend/Conventions.v, using the systematic derivation, and removes the platform-specific definitions. This reduces code and proof size, and makes it easier to change the calling conventions.
* Support re-normalization of values returned by function callsXavier Leroy2020-02-211-0/+6
| | | | | | | | | | | | | | | | | | | | | | | | | Some ABIs leave more flexibility concerning function return values than CompCert expects. For example, the x86 ABI says that a function result of type "char" is returned in register AL, leaving the top 24 bits of register EAX unspecified, while CompCert expects EAX to contain 32 valid bits, namely the zero- or sign-extension of the 8-bit result. This commits adds a general mechanism to insert "re-normalization" conversions on the results of function calls. Currently, it only deals with results of small integer types, and inserts zero- or sign-extensions if so instructed by a platform-dependent function, Convention1.return_value_needs_normalization. The conversions in question are inserted early in the front-end, so that they can be optimized away in the back-end. The semantic preservation proof is still conducted against the CompCert model, where the return values of functions are already normalized. What the proof shows is that the extra conversions have no effect in this case. In future work we could relax the CompCert model, allowing functions to return values that are not normalized.
* Refine the type of function results in AST.signatureXavier Leroy2020-02-211-11/+10
| | | | | | | | | | 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.
* Remove coq warnings (#28)Bernhard Schommer2017-09-221-2/+2
| | | | Replace deprecated functions and theorems from the Coq standard library (version 8.6) by their non-deprecated counterparts.
* riscV/Conventions1: in 32-bit mode, wrong size for stack-allocated arguments ↵Xavier Leroy2017-08-261-2/+5
| | | | | | of type Tfloat A default size of 1 was used instead of the correct "typesize ty".
* Bring RISC-V port up to dateXavier Leroy2017-05-051-2/+4
| | | | Commit 7873af3 introduced changes in the Conventions1.v interface. This commit implements those changes for RISC-V.
* RISC-V port and assorted changesXavier Leroy2017-04-281-0/+436
This commits adds code generation for the RISC-V architecture, both in 32- and 64-bit modes. The generated code was lightly tested using the simulator and cross-binutils from https://riscv.org/software-tools/ This port required the following additional changes: - Integers: More properties about shrx - SelectOp: now provides smart constructors for mulhs and mulhu - SelectDiv, 32-bit integer division and modulus: implement constant propagation, use the new smart constructors mulhs and mulhu. - Runtime library: if no asm implementation is provided, run the reference C implementation through CompCert. Since CompCert rejects the definitions of names of special functions such as __i64_shl, the reference implementation now uses "i64_" names, e.g. "i64_shl", and a renaming "i64_ -> __i64_" is performed over the generated assembly file, before assembling and building the runtime library. - test/: add SIMU make variable to run tests through a simulator - test/regression/alignas.c: make sure _Alignas and _Alignof are not #define'd by C headers commit da14495c01cf4f66a928c2feff5c53f09bde837f Author: Xavier Leroy <xavier.leroy@inria.fr> Date: Thu Apr 13 17:36:10 2017 +0200 RISC-V port, continued Now working on Asmgen. commit 36f36eb3a5abfbb8805960443d087b6a83e86005 Author: Xavier Leroy <xavier.leroy@inria.fr> Date: Wed Apr 12 17:26:39 2017 +0200 RISC-V port, first steps This port is based on Prashanth Mundkur's experimental RV32 port and brings it up to date with CompCert, and adds 64-bit support (RV64). Work in progress.