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CC 2022
Tue 5 - Wed 6 April 2022 Online conference
Wed 6 Apr 2022 13:00 - 13:15 at CC Virtual Room - Session 6: Performance Optimizations Chair(s): Doru Thom Popovici

Modern CPUs utilize SIMD vector instructions and hardware extensions to accelerate code with data-level parallelism. This allows for high performance gains in select application domains such as image and signal processing. However, general purpose code often lacks data-level parallelism or has complex control and data dependencies, which prevents vectorization. Thus, CPU vector registers and functional units frequently sit idle while the scalar datapath unilaterally executes code. In this paper, we present Loner, a profile-guided compiler methodology for optimizing scalar integer loops using the otherwise idle vector datapath. Loner expands the traditional definition of vectorization by identifying two situations where it is beneficial to perform vector operations with a single data element (“Loner” data). In the first, the scalar register file and functional units are overburdened, resulting in unnecessary spill/reload operations and stalls due to structural hazards. In the second, we describe a set of “vector-amenable” computation patterns that the vector pipeline naturally executes more efficiently than its scalar counterpart. Loner identifies hot code regions that exhibit either characteristic and offloads a subset of a program’s computation graph to the vector datapath for maximum performance. We evaluate Loner on an x86 Whiskey Lake processor using select benchmarks from the SPEC, GAP, and MiBench benchmark suites where it improves performance by 2.64% (geomean) up to 40.28%.

Wed 6 Apr

Displayed time zone: Eastern Time (US & Canada) change

13:00 - 14:00
Session 6: Performance OptimizationsCC Research Papers at CC Virtual Room
Chair(s): Doru Thom Popovici Lawrence Berkeley National Lab
13:00
15m
Paper
Loner: Utilizing the CPU Vector Datapath to Process Scalar Integer Data
CC Research Papers
Armand Behroozi University of Michigan, Sunghyun Park University of Michigan, Scott Mahlke University of Michigan
DOI
13:15
15m
Paper
Mapping Parallelism in a Functional IR through Constraint SatisfactionArtifacts Evaluated – Reusable v1.1Artifacts Available v1.1Results Reproduced v1.1
CC Research Papers
Naums Mogers University of Edinburgh, Lu Li University of Edinburgh, Valentin Radu University of Sheffield, Christophe Dubach McGill University
DOI
13:30
15m
Paper
Software Pre-execution for Irregular Memory Accesses in the HBM Era
CC Research Papers
DOI
13:45
15m
Paper
Efficient Profile-Guided Size Optimization for Native Mobile Applications
CC Research Papers
Kyungwoo Lee Meta, Ellis Hoag Meta, Nikolai Tillmann Meta Platforms, Inc.
DOI