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<?xml version="1.0" encoding="UTF-8"?> |
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<!-- |
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Copyright (c) 2017 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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<section xmlns="http://docbook.org/ns/docbook" |
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xmlns:xi="http://www.w3.org/2001/XInclude" |
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xmlns:xlink="http://www.w3.org/1999/xlink" |
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version="5.0" |
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xml:id="sec_differences"> |
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<title>Profound differences</title> |
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<para>We have already mentioned above a number of architectural differences |
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that affect porting of codes containing Intel intrinsics to POWER. The fact |
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that Intel supports multiple vector extensions with different vector widths |
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(64, 128, 256, and 512 bits) while the PowerISA only supports vectors of |
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128 bits is one issue. Another is the difference in how the respective ISAs |
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support scalars in vector registers. In the text above we propose |
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workable alternatives for the PowerPC port. There are also differences in the |
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handling of floating point exceptions and rounding modes that may impact the |
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application's performance or behavior.</para> |
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<xi:include href="sec_floatingpoint_exceptions.xml"/> |
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<xi:include href="sec_floatingpoint_rounding.xml"/> |
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<xi:include href="sec_performance.xml"/> |
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</section> |
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