Widen default vector size

Registered by Michael Hope on 2011-09-13

Change the default vector size for NEON to 128 bits.

The NEON unit can work on double word or quad word values. For historical reasons the ARM backend defaults to double word operations when using the vectoriser. Switching to quad word lets twice the number of values be done in one instruction, which can double performance in some situations.

Blueprint information

Status:
Complete
Approver:
Michael Hope
Priority:
Medium
Drafter:
Ira Rosen
Direction:
Approved
Assignee:
Ira Rosen
Definition:
Approved
Series goal:
Accepted for 4.6
Implementation:
Implemented
Milestone target:
milestone icon 4.6-2011.10
Started by
Michael Hope on 2011-09-13
Completed by
Michael Hope on 2011-10-13

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Whiteboard

Headline: Improve performance by using NEON quad-word vectors by default
Acceptance: https://wiki.linaro.org/WorkingGroups/ToolChain/std-performance-acceptance

Committed upstream[1]. In shake down. Targeted at 2011.10 as it should be clear by then.

Headline: Change the default vector size for NEON to 128 bits.

Acceptance:

[1] http://gcc.gnu.org/ml/gcc-cvs/2011-09/msg00199.html on 2011-09-06

(?)

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