4 research outputs found
Deriving abstract transfer functions for analyzing embedded software
ManuscriptThis paper addresses the problem of creating abstract transfer functions supporting dataflow analyses. Writing these functions by hand is problematic: transfer functions are difficult to understand, difficult to make precise, and difficult to debug. Bugs in transfer functions are particularly serious since they defeat the soundness of any program analysis running on top of them. Furthermore, implementing transfer functions by hand is wasteful because the resulting code is often difficult to reuse in new analyzers and to analyze new languages. We have developed algorithms and tools for deriving transfer functions for the bitwise and unsigned interval abstract domains. The interval domain is standard; in the bitwise domain, values are vectors of three-valued bits. For both domains, important challenges are to derive transfer functions that are sound in the presence of integer overflow, and to derive precise transfer functions for operations whose semantics are a mismatch for the domain (i.e., bit-vector operations in the interval domain and arithmetic operations in the bitwise domain). We can derive transfer functions, and execute them, in time linear in the bitwidth of the operands. These functions are maximally precise in most cases. Our generated transfer functions are parameterized by a bitwidth and are independent of the language being analyzed, and also of the language in which the analyzer is written. Currently, we generate interval and bitwise transfer functions in C and OCaml for analyzing C source code, ARM object code, and AVR object code. We evaluate our derive functions by using them in an interprocedural dataflow analyzer
Survey on Instruction Selection: An Extensive and Modern Literature Review
Instruction selection is one of three optimisation problems involved in the
code generator backend of a compiler. The instruction selector is responsible
of transforming an input program from its target-independent representation
into a target-specific form by making best use of the available machine
instructions. Hence instruction selection is a crucial part of efficient code
generation.
Despite on-going research since the late 1960s, the last, comprehensive
survey on the field was written more than 30 years ago. As new approaches and
techniques have appeared since its publication, this brings forth a need for a
new, up-to-date review of the current body of literature. This report addresses
that need by performing an extensive review and categorisation of existing
research. The report therefore supersedes and extends the previous surveys, and
also attempts to identify where future research should be directed.Comment: Major changes: - Merged simulation chapter with macro expansion
chapter - Addressed misunderstandings of several approaches - Completely
rewrote many parts of the chapters; strengthened the discussion of many
approaches - Revised the drawing of all trees and graphs to put the root at
the top instead of at the bottom - Added appendix for listing the approaches
in a table See doc for more inf