CR for RFR 8140779

Berg, Michael C michael.c.berg at
Thu Oct 29 19:06:58 UTC 2015

Hi Folks,

I would like to contribute AVX 512 changes for bug fixes and performance issues. I need two reviewers to examine this patch and comment as needed:



Debugging on Evex machines, a number of issues were uncovered which could not be addressed via emulation. These changes include a unified approach with call frames for Evex and pre Evex targets, performance changes for 32 bit Evex performance, general improvements to all x86 targets for reduction patterns, encoding changes for correctness, changes that reduce register pressure for generated code, CPUID additions for additional state control, vector length guards on instructions which only partially support Evex on some targets. Also included are the addition of a state object which is atomic to each instruction emit and which is programmed with specific target information. There is a reduction of x86 assembler interfaces from 20 to 4. Code which manages the legacy code path for instructions which do not have Evex support is also included which must manage upper bank resources of registers while avoiding complication in the register allocator which would bloat code.

Please consider this a high priority review for target system usage.


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