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* Platform-independent implementation of Conventions.size_arguments (#222)Xavier Leroy2020-02-241-107/+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.
* AArch64: normalize function return values of small integer typeXavier Leroy2020-02-211-3/+11
| | | | | | | According to AAPCS64 (the AArch64 ABI specification), the top bits of the register containing the function result have unspecified value, so we need to sign- or zero-extend the function result before using it, as in the x86 port.
* Support re-normalization of values returned by function callsXavier Leroy2020-02-211-0/+5
| | | | | | | | | | | | | | | | | | | | | | | | | 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 Leroy2020-02-212-10/+9
| | | | | | | | | | 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.
* Revert "Remove `__builtin_nop` for some architectures. (#208)"Bernhard Schommer2020-01-033-1/+8
| | | | This reverts commit 4dfcd7d4be18e8bc437ca170782212aa06635a95.
* Remove `__builtin_nop` for some architectures. (#208)Bernhard Schommer2019-12-213-8/+1
| | | | | | | The `__builtin_nop` function is documented only for PowerPC. It was added to the other architectures by copy paste, but has no known uses. So, remove `__builtin_nop` from all architectures but PowerPC.
* The SP register has dwarf register number 31.Bernhard Schommer2019-12-111-1/+1
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* Fix for AArch64 alignment problem (#206)Bernhard Schommer2019-11-283-2/+8
| | | | | | | | | In addressing modes for load and store instructions, the offset must be a multiple of the memory size being accessed. When accessing global variables, this may not be the case if the alignment of the variable is less than its size. Errors occur at link time. This PR extends the check for a representable offset for the addressing of global variables to also check whether the variable is correctly aligned. Only if both conditions are met can we generate the short sequence Padrp / ADadr. Otherwise we go through the generic loadsymbol sequence.
* Added dwarf register numbers for aarch64Bernhard Schommer2019-11-281-3/+18
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* Asmgenproof1: useless unfolding in proof scripts causing "omega" to failXavier Leroy2019-09-111-3/+3
| | | | "omega" fails in Coq 8.7, but not in 8.8 and later.
* AArch64: wrong expected type for arguments of Cmaskl{zero,notzero}aarch64xavier.leroy2019-08-312-4/+4
| | | | | | | | The argument is of type Tlong, not Tint. This caused spurious errors in RTLtyping. Also: in AArch64/PrintOp.ml, print Cmaskl{zero,notzero} with "&l" to distinguish them from Cmask{zero,notzero}.
* Offset out of range for ldp/stp instructionsxavier.leroy2019-08-231-1/+3
| | | | These instructions are generated by __builtin_memcpy.
* AArch64 portXavier Leroy2019-08-0827-0/+14370
This commit adds a back-end for the AArch64 architecture, namely ARMv8 in 64-bit mode.