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31 lines
878 B
HTML
31 lines
878 B
HTML
<html><head><link rel="stylesheet" href="style.css"></head><body><div class="page">
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<h1>20160706 - Low Cost Branching to Factoring Out Loop Exit Check</h1>
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<br>
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Threading to hide pipeline depth combined with an ISA which makes branching cheep is one goal.
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Specifically absolute branching with immediate destination in the opcode word
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(single word branch/call, no adder), and instructions which include a return flag (make returns free).
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Enables easy computed branches, both for jump tables, and loops.
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Can factor out loop check into hierarchical call tree,
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<br>
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<br><tt>
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Do4: Unroll work four times; Return;<br>
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Do16: Call Do4; Call Do4; Call Do4; Jump Do4;<br>
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Do64: Call Do16; Call Do16; Call Do16; Jump Do16;<br>
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... etc ...
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</tt><br>
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<br>
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Can use a computed branch to jump into the tree for other loop counts.
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</div></body></html>
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