First up, this commit now sets the spin count to 1 for x86 hybrid platforms like Intel Core Alder Lake and Raptor Lake processors. With this tweak to the OpenMP spin count value, Intel is seeing a variety of -- mostly small -- improvements to the performance on the likes of SPEC CPU 2017 and OMP2012 test cases. Overall though for this modest change it seems to provide a win overall for the performance and on top of all the other hybrid-related optimizations Intel has made across the Linux software stack over the past 2+ years.
Another change committed today is adding Intel USER_MSR support that is enabled with the new "-musermsr" option. USER_MSR is new with Intel's Clearwater Forest for the URDMSR and UWRMSR instructions. These are new instructions for user read and user write of model-specific registers.
The third notable Intel commit for the day is APX PUSH2POP2 support . This new instruction support is part of the ongoing compiler enablement for Advanced Performance Extensions (APX). The APX PUSH2/POP2 instructions transfer two register values within a single memory operation.
Great as always seeing the countless contributions made by Intel open-source compiler engineers to GCC not only for their future processors / ISA extensions but also general performance optimizations and other tuning. GCC 14.1 will be out in the early months of 2024 as the first stable version of GCC 14.