[PATCH] D55710: add pragmas to control Software Pipelining optimisation

[Aaron Ballman via Phabricator via cfe-commits]

aaron.ballman added inline comments.


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Comment at: include/clang/Basic/AttrDocs.td:2650
+    Software Pipelining optimization is a technique used to optimize loops by
+  utilizing instructions level parallelism. It reorders loop instructions to
+  overlap iterations. As the result next iteration started before previous
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instructions level -> instruction-level


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Comment at: include/clang/Basic/AttrDocs.td:2651
+  utilizing instructions level parallelism. It reorders loop instructions to
+  overlap iterations. As the result next iteration started before previous
+  have finished. The Modulo Scheduling technique creates schedule for one
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As a result, the next iteration starts before the previous iteration has finished.


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Comment at: include/clang/Basic/AttrDocs.td:2652-2654
+  have finished. The Modulo Scheduling technique creates schedule for one
+  iteration such that when repeating at regular interval no inter-iteration
+  dependence violated. This constant interval(in cycles) between the start
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The module scheduling technique creates a schedule for one iteration such that when repeating at regular intervals, no inter-iteration dependencies are violated.


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Comment at: include/clang/Basic/AttrDocs.td:2655
+  dependence violated. This constant interval(in cycles) between the start
+  of iterations called initiation interval. Cycles number of one iteration
+  of newly generated loop matches with Initiation Interval. For further
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is called the initiation interval.

I can't quite parse the second sentence, though. Is it trying to say that the initiation interval is the number of cycles for a single iteration of the optimized loop?


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Comment at: include/clang/Basic/AttrDocs.td:2676
+  the software pipeliner to try the specified initiation interval.
+  If schedule found the resulting loop iteration would have specified
+  cycle count. The positive number greater than zero can be specified:
----------------
I'm can't quite parse this sentence either. Is it trying to say that the scheduler will try to find a loop iteration cycle count that most-closely matches the specified initiation interval?


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Comment at: include/clang/Basic/AttrDocs.td:2677
+  If schedule found the resulting loop iteration would have specified
+  cycle count. The positive number greater than zero can be specified:
+
----------------
The initiation interval must be a positive number greater than zero.


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https://reviews.llvm.org/D55710