Post-silicon bug localization -- the process of identifying the location of a detected hardware bug and the cycle(s) during which the bug produces error(s) -- is a major bottleneck for complex integrated circuits. Instruction Footprint Recording and Analysis (IFRA) is a promising post-silicon bug localization technique for complex processor cores. However, applying IFRA to new processor microarchitectures can be challenging due to the manual effort required to implement special microarchitecture-dependent analysis techniques for bug localization. This paper presents the Bug Localization Graph (BLoG) framework that enables application of IFRA to new processor microarchitectures with reduced manual effort. Results obtained from an industrial microarchitectural simulator modeling a state-of-the-art complex commercial microarchitecture (Intel Nehalem, the foundation for the Intel Core™ i7 and Core™ i5 processor families) demonstrate that BLoG-assisted IFRA enables effective and efficient post-silicon bug localization for complex processors with high bug localization accuracy at low cost.

Long error detection latency, the time elapsed between the occurrence of an error caused by a bug and its manifestation as a system-level failure, is a major challenge in post-silicon validation of robust systems. In this paper, we present a new technique called Quick Error Detection (QED), which transforms existing post-silicon validation tests into new validation tests that significantly reduce error detection latency. QED transformations allow flexible tradeoffs between error detection latency, coverage, and complexity, and can be implemented in software with little or no hardware changes. Results obtained from hardware experiments on quad-core Intel®Core™ i7 hardware platforms and from simulations on a multi-core MIPS processor design demonstrate that: 1. QED significantly improves error detection latencies by six orders of magnitude, i.e., from billions of cycles to a few thousand cycles or less. 2. QED transformations do not degrade the coverage of validation tests as estimated empirically by measuring the maximum operating frequencies over a wide range of operating voltage points. 3. QED tests improve coverage by detecting errors that escape the original non-QED tests.

Instruction Footprint Recording and Analysis (IFRA) overcomes challenges associated with an expensive step in post-silicon validation of processors-pinpointing the bug location and the instruction sequence that exposes the bug from a system failure. On-chip recorders collect instruction footprints (information about flows of instructions and what the instructions did as they passed through various design blocks) during the normal operation of the processor in a post-silicon system validation setup. Upon system failure, the recorded information is scanned out and analyzed offline for bug localization. Special self-consistency-based program analysis techniques, together with the test program binary of the application executed during post-silicon validation, are used for this purpose. Major benefits of using IFRA over traditional techniques for post-silicon bug localization are as follows: 1) it does not require full system-level reproduction of bugs, and 2) it does not require full system-level simulation. Simulation results on a complex superscalar processor demonstrate that IFRA is effective in accurately localizing electrical bugs with very little impact on overall chip area.

Many image processing applications require fast convolution of an image with one or more 2D filters. Field-Programmable Gate Arrays (FPGAs) are often used to achieve this goal due to their fine grain parallelism and reconfigurability. However, the heterogeneous nature of modern reconfigurable devices is not usually considered during design optimization. This article proposes an algorithm that explores the space of possible implementation architectures of 2D filters, targeting the minimization of the required area, by optimizing the usage of the different components in a heterogeneous device. This is achieved by exploring the heterogeneous nature of modern reconfigurable devices using a Singular Value Decomposition based algorithm, which provides an efficient mapping of filter's implementation requirements to the heterogeneous components of modern FPGAs. In the case of multiple 2D filters, the proposed algorithm also exploits any redundancy that exists within each filter and between different filters in the set, leading to designs with minimized area. Experiments with real filter sets from computer vision applications demonstrate an average of up to 38% reduction in the required area.

The objective of IFRA, Instruction Footprint Recording and Analysis, is to overcome the challenges associated with a very expensive step in post-silicon validation of processors -- bug localization in a system setup. IFRA consists of special design and analysis techniques required to bridge a major gap between system-level and circuit-level debug. Special hardware recorders, called Footprint Recording Structures (FRS's), record semantic information about data and control flows of instructions passing through various design blocks of a processor. This information is recorded concurrently during normal operation of a processor in a post-silicon system validation setup. Upon detection of a problem, the recorded information is scanned out and analyzed for bug localization. Special program analysis techniques, together with the binary of the application executed during post-silicon validation, are used for the analysis. IFRA does not require full system-level reproduction of bugs or system-level simulation. Simulation results on a complex super-scalar processor demonstrate that IFRA is effective in accurately localizing bugs with very little impact on overall chip area.

Conventional register file architectures cannot optimally exploit temporal locality in data references due to their limited capacity and static encoding of register addresses in instructions. In conventional embedded architectures, the register file capacity cannot be increased without resorting to longer instruction words. Similarly, loop unrolling is often required to exploit locality in the register file accesses across iterations because naming registers statically is inflexible. Both optimizations lead to significant code size increases, which is undesirable in embedded systems. In this paper, the authors introduce the register pointer architecture (RPA), which allows registers to be accessed indirectly through register pointers. Indirection allows a larger register file to be used without increasing the length of instruction words. Additional register file capacity allows many loads and stores, such as those introduced by spill code, to be eliminated, which improves performance and reduces energy consumption. Moreover, indirection affords additional flexibility in naming registers, which reduces the need to apply loop unrolling in order to maximize reuse of register allocated variables