4,967 research outputs found
Designing a CPU model: from a pseudo-formal document to fast code
For validating low level embedded software, engineers use simulators that
take the real binary as input. Like the real hardware, these full-system
simulators are organized as a set of components. The main component is the CPU
simulator (ISS), because it is the usual bottleneck for the simulation speed,
and its development is a long and repetitive task. Previous work showed that an
ISS can be generated from an Architecture Description Language (ADL). In the
work reported in this paper, we generate a CPU simulator directly from the
pseudo-formal descriptions of the reference manual. For each instruction, we
extract the information describing its behavior, its binary encoding, and its
assembly syntax. Next, after automatically applying many optimizations on the
extracted information, we generate a SystemC/TLM ISS. We also generate tests
for the decoder and a formal specification in Coq. Experiments show that the
generated ISS is as fast and stable as our previous hand-written ISS.Comment: 3rd Workshop on: Rapid Simulation and Performance Evaluation: Methods
and Tools (2011
A formally verified compiler back-end
This article describes the development and formal verification (proof of
semantic preservation) of a compiler back-end from Cminor (a simple imperative
intermediate language) to PowerPC assembly code, using the Coq proof assistant
both for programming the compiler and for proving its correctness. Such a
verified compiler is useful in the context of formal methods applied to the
certification of critical software: the verification of the compiler guarantees
that the safety properties proved on the source code hold for the executable
compiled code as well
A Language and Hardware Independent Approach to Quantum-Classical Computing
Heterogeneous high-performance computing (HPC) systems offer novel
architectures which accelerate specific workloads through judicious use of
specialized coprocessors. A promising architectural approach for future
scientific computations is provided by heterogeneous HPC systems integrating
quantum processing units (QPUs). To this end, we present XACC (eXtreme-scale
ACCelerator) --- a programming model and software framework that enables
quantum acceleration within standard or HPC software workflows. XACC follows a
coprocessor machine model that is independent of the underlying quantum
computing hardware, thereby enabling quantum programs to be defined and
executed on a variety of QPUs types through a unified application programming
interface. Moreover, XACC defines a polymorphic low-level intermediate
representation, and an extensible compiler frontend that enables language
independent quantum programming, thus promoting integration and
interoperability across the quantum programming landscape. In this work we
define the software architecture enabling our hardware and language independent
approach, and demonstrate its usefulness across a range of quantum computing
models through illustrative examples involving the compilation and execution of
gate and annealing-based quantum programs
First steps towards the certification of an ARM simulator using Compcert
The simulation of Systems-on-Chip (SoC) is nowadays a hot topic because,
beyond providing many debugging facilities, it allows the development of
dedicated software before the hardware is available. Low-consumption CPUs such
as ARM play a central role in SoC. However, the effectiveness of simulation
depends on the faithfulness of the simulator. To this effect, we propose here
to prove significant parts of such a simulator, SimSoC. Basically, on one hand,
we develop a Coq formal model of the ARM architecture while on the other hand,
we consider a version of the simulator including components written in
Compcert-C. Then we prove that the simulation of ARM operations, according to
Compcert-C formal semantics, conforms to the expected formal model of ARM. Size
issues are partly dealt with using automatic generation of significant parts of
the Coq model and of SimSoC from the official textual definition of ARM.
However, this is still a long-term project. We report here the current stage of
our efforts and discuss in particular the use of Compcert-C in this framework.Comment: First International Conference on Certified Programs and Proofs 7086
(2011
Enabling Cross-Event Optimization in Discrete-Event Simulation Through Compile-Time Event Batching
A discrete-event simulation (DES) involves the execution of a sequence of
event handlers dynamically scheduled at runtime. As a consequence, a priori
knowledge of the control flow of the overall simulation program is limited. In
particular, powerful optimizations supported by modern compilers can only be
applied on the scope of individual event handlers, which frequently involve
only a few lines of code. We propose a method that extends the scope for
compiler optimizations in discrete-event simulations by generating batches of
multiple events that are subjected to compiler optimizations as contiguous
procedures. A runtime mechanism executes suitable batches at negligible
overhead. Our method does not require any compiler extensions and introduces
only minor additional effort during model development. The feasibility and
potential performance gains of the approach are illustrated on the example of
an idealized proof-ofconcept model. We believe that the applicability of the
approach extends to general event-driven programs
Static analysis of energy consumption for LLVM IR programs
Energy models can be constructed by characterizing the energy consumed by
executing each instruction in a processor's instruction set. This can be used
to determine how much energy is required to execute a sequence of assembly
instructions, without the need to instrument or measure hardware.
However, statically analyzing low-level program structures is hard, and the
gap between the high-level program structure and the low-level energy models
needs to be bridged. We have developed techniques for performing a static
analysis on the intermediate compiler representations of a program.
Specifically, we target LLVM IR, a representation used by modern compilers,
including Clang. Using these techniques we can automatically infer an estimate
of the energy consumed when running a function under different platforms, using
different compilers.
One of the challenges in doing so is that of determining an energy cost of
executing LLVM IR program segments, for which we have developed two different
approaches. When this information is used in conjunction with our analysis, we
are able to infer energy formulae that characterize the energy consumption for
a particular program. This approach can be applied to any languages targeting
the LLVM toolchain, including C and XC or architectures such as ARM Cortex-M or
XMOS xCORE, with a focus towards embedded platforms. Our techniques are
validated on these platforms by comparing the static analysis results to the
physical measurements taken from the hardware. Static energy consumption
estimation enables energy-aware software development, without requiring
hardware knowledge
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VSS : a VHDL synthesis system
This report describes a register transfer synthesis system that allows a designer to interact with the design process. The designer can modify the compiled design by changing the input description, selecting optimization and mapping strategies, or graphically changing the generated design schematic. The VHDL language is used for input and output descriptions. An intermediate representation which incorporates signal typing and component attributes simplifies compilation and facilitates design optimization. The compilation process consists of two phases. First, a design composed of generic components is synthesized from the input description. Second, this design is translated into components from a particular library by a mapper and optimized by a logic optimizer. Redesign to new technologies can be accomplished by changing only the component library
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