Floating-point arithmetic is natively supported in hardware and the preferred choice when implementing numerical software in scientific or engineering applications. However, such programs are notoriously hard to analyze due to round-off errors and the frequent use of elementary functions such as log, arctan, or sqrt. In this work, we present the Two Variables per Inequality Floating-Point (TVPI-FP) domain, a numerical and constraint-based abstract domain designed for the analysis of floating-point programs. TVPI-FP supports all features of real-world floating-point programs including conditional branches, loops, and elementary functions and it is efficient asymptotically and in practice. Thus it overcomes limitations of prior tools that often are restricted to straight-line programs or require the use of expensive solvers. The key idea is the consistent use of interval arithmetic in inequalities and an associated redesign of all operators. Our extensive experiments show that TVPI-FP is often orders of magnitudes faster than more expressive tools at competitive, or better precision while also providing broader support for realistic programs with loops and conditionals.

Floating-point arithmetic is extensively used in scientific and engineering applications to approximate real arithmetic. Unfortunately, floating-point arithmetic is not a sound implementation of real arithmetic, i.e., it may produce different results, does not provide error guarantees, and the errors can become arbitrarily large. In this paper, we introduce SafeGen, a source-to-source compiler that rewrites a given C program using floating-point arithmetic to an efficient C program performing the same computation soundly, i.e., it returns an error bound that is guaranteed to contain the correct result of the program if it had been executed in real arithmetic. Equivalently, it gives a precision certificate on the number of correct bits in the result. SafeGen uses affine arithmetic (AA) that keeps accuracy high compared to interval arithmetic by preserving linear correlations between variables. To mitigate its high cost, SafeGen combines a novel form of static analysis to identify these correlations with a flexible policy-based approach for their selection. SafeGen supports SIMD intrinsics in the input and can output SIMDoptimized code. Our results show that SafeGen-generated code is 30–70 times faster than manually rewritten code using AA libraries. Equivalently, SafeGen can offer many more bits of certified accuracy within a reduced time budget.

Floating-point arithmetic is widely used by software developers but is unsound, i.e., there is no guarantee on the accuracy obtained, which can be imperative in safety-critical applications. We present IGen, a source-to-source compiler that translates a given C function using floating-point into an equivalent sound C function that uses interval arithmetic. IGen supports Intel SIMD intrinsics in the input function using a specially designed code generator and can produce SIMD-optimized output. To mitigate a possible loss of accuracy due to the increase of interval sizes, IGen can compile to double-double precision, again SIMD-optimized. Finally, IGen implements an accuracy optimization for the common reduction pattern. We benchmark our compiler on high-performance code in the domain of linear algebra and signal processing. The results show that the generated code delivers sound double precision results at high performance. In particular, we observe speed-ups of up to 9.8 when compared to commonly used interval libraries using double precision. When compiling to double-double, our compiler delivers intervals that keep error accumulation small enough to compute results with at most one bit of error in double precision, i.e., certified double precision results.