Difference between revisions of "Instruction Set/smearx"
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{{DISPLAYTITLE:smearx}} | {{DISPLAYTITLE:smearx}} | ||
| − | <div style="font-size:80%;line-height:90%;margin-bottom:2em">[[Speculation| | + | <div style="font-size:80%;line-height:90%;margin-bottom:2em">[[Speculation|speculable]] [[Encoding|exu stream]] [[Decode|exu block]] [[Phasing|compute phase]] operation [[Domains|in the logical value domain]] <br /> |
'''native on:''' [[Cores|all]]<br /> | '''native on:''' [[Cores|all]]<br /> | ||
</div> | </div> | ||
| − | + | Find the first one in a bool vector, shift it one to the right and set all remaining elments to one too. | |
| + | |||
| + | The main purpose of this operation is to facilitate vectorization of loops, do-while loops in particular. | ||
| + | It allows you to treat conditions created in a <abbr title="single instruction, multple data">SIMD</abbr> as exit conditions in a loop, since the first occurrence of a true value applies to all the remaining values and would be iterations. | ||
| + | |||
| + | {| class="wikitable" | ||
| + | |- | ||
| + | ||0||0||0||0||1||0||0||0 | ||
| + | |} | ||
| + | |||
| + | becomes | ||
| + | |||
| + | {| class="wikitable" | ||
| + | |- | ||
| + | ||0||0||0||0||0||1||1||1 | ||
| + | |} | ||
| + | |||
| + | which then can be used in [[Instruction_Set/pick|pick]] operations or other vector operations, yet the exit condition is preserved for all elements that would not be in the iteration anymore if it wasn't vectorized. | ||
| + | Since the rightmost value would be shifted out, a second result value is returned to the belt which holds that value. It always must be checked too for the exit condition. | ||
| + | |||
| + | <b>related operations:</b> [[Instruction_Set/smeari|smeari]], [[Instruction_Set/left|left]], [[Instruction_Set/mask|mask]] | ||
| + | |||
---- | ---- | ||
<code style="font-size:130%"><b style="color:#050">smearx</b>(<span style="color:#009">[[Domains#op|op]]</span> <span title="belt operand from ops window">vs</span>) → [[Domains#op|op]] r<sub>0</sub>, [[Domains#op|op]] r<sub>1</sub></code> | <code style="font-size:130%"><b style="color:#050">smearx</b>(<span style="color:#009">[[Domains#op|op]]</span> <span title="belt operand from ops window">vs</span>) → [[Domains#op|op]] r<sub>0</sub>, [[Domains#op|op]] r<sub>1</sub></code> | ||
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! [[Cores|Core]] || [[Slot|In Slots]]|| [[Latency|Latencies]] | ! [[Cores|Core]] || [[Slot|In Slots]]|| [[Latency|Latencies]] | ||
|- | |- | ||
| − | | [[Cores/Tin/Encoding# | + | | [[Cores/Tin/Encoding#smearx|Tin]] || E0 || 1 |
|- | |- | ||
| − | | [[Cores/Copper/Encoding# | + | | [[Cores/Copper/Encoding#smearx|Copper]] || E0 || 1 |
|- | |- | ||
| − | | [[Cores/Silver/Encoding# | + | | [[Cores/Silver/Encoding#smearx|Silver]] || E0 E1 E2 E3 || 1 |
|- | |- | ||
| − | | [[Cores/Gold/Encoding# | + | | [[Cores/Gold/Encoding#smearx|Gold]] || E0 || 1 |
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
|} | |} | ||
| + | |||
| + | |||
| + | [[Instruction_Set|Instruction Set, alphabetical]], [[Instruction Set by Category]], [http://millcomputing.com/instructions.html?collapse=7#ops Instruction Set, sortable, filterable] | ||
Latest revision as of 13:24, 23 February 2021
Find the first one in a bool vector, shift it one to the right and set all remaining elments to one too.
The main purpose of this operation is to facilitate vectorization of loops, do-while loops in particular. It allows you to treat conditions created in a SIMD as exit conditions in a loop, since the first occurrence of a true value applies to all the remaining values and would be iterations.
| 0 | 0 | 0 | 0 | 1 | 0 | 0 | 0 |
becomes
| 0 | 0 | 0 | 0 | 0 | 1 | 1 | 1 |
which then can be used in pick operations or other vector operations, yet the exit condition is preserved for all elements that would not be in the iteration anymore if it wasn't vectorized. Since the rightmost value would be shifted out, a second result value is returned to the belt which holds that value. It always must be checked too for the exit condition.
related operations: smeari, left, mask
operands: like Smearx XX:Xx
| Core | In Slots | Latencies |
|---|---|---|
| Tin | E0 | 1 |
| Copper | E0 | 1 |
| Silver | E0 E1 E2 E3 | 1 |
| Gold | E0 | 1 |
Instruction Set, alphabetical, Instruction Set by Category, Instruction Set, sortable, filterable
