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57 lines
2.0 KiB
XML
57 lines
2.0 KiB
XML
5 years ago
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Copyright (c) 2019 OpenPOWER Foundation
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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-->
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<chapter version="5.0" xml:lang="en" xmlns="http://docbook.org/ns/docbook" xmlns:xi="http://www.w3.org/2001/XInclude"
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xmlns:xlink="http://www.w3.org/1999/xlink" xml:id="section_techniques">
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<!-- Chapter Title goes here. -->
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<title>Vector Programming Techniques</title>
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<section>
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<title>Help the Compiler Help You</title>
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<para>
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Start with scalar code, which is the most portable. Use various
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tricks for helping the compiler vectorize scalar code. Make
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sure you align your data on 16-byte boundaries wherever
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possible, and tell the compiler it's aligned. Use __restrict__
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pointers to promise data does not alias.
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</para>
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</section>
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<section>
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<title>Use Portable Intrinsics</title>
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<para>
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Individual compilers may provide other intrinsic support. Only
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the intrinsics in this manual are guaranteed to be portable
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across compliant compilers.
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</para>
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<para>
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Some compilers may provide compatibility headers for use with
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other architectures. Recent GCC and Clang compilers support
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compatibility headers for the lower levels of the x86 vector
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architecture. These can be used initially for ease of porting,
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but for best performance, it is preferable to rewrite important
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sections of code with native Power intrinsics.
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</para>
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</section>
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<section>
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<title>Use Assembly Code Sparingly</title>
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<para>filler</para>
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</section>
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</chapter>
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