[llvm] r366961 - Apply a few more reviewer suggestions from D65164
Philip Reames via llvm-commits
llvm-commits at lists.llvm.org
Wed Jul 24 16:30:56 PDT 2019
Author: reames
Date: Wed Jul 24 16:30:56 2019
New Revision: 366961
URL: http://llvm.org/viewvc/llvm-project?rev=366961&view=rev
Log:
Apply a few more reviewer suggestions from D65164
Modified:
llvm/trunk/docs/LoopTerminology.rst
Modified: llvm/trunk/docs/LoopTerminology.rst
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/docs/LoopTerminology.rst?rev=366961&r1=366960&r2=366961&view=diff
==============================================================================
--- llvm/trunk/docs/LoopTerminology.rst (original)
+++ llvm/trunk/docs/LoopTerminology.rst Wed Jul 24 16:30:56 2019
@@ -80,18 +80,23 @@ Preheader Block - A preheader is a (sing
ends in an unconditional transfer of control to the loop header. Note
that not all loops have such blocks.
-Backedge Taken Count - The number of times the backedge will have
-executed before some interesting event happens. Commonly used without
+Backedge Taken Count - The number of times the backedge will execute
+before some interesting event happens. Commonly used without
qualification of the event as a shorthand for when some exiting block
branches to some exit block. May be zero, or not statically computable.
-Iteration Count - The number of times the header has executed before
-some interesting event happens. Commonly used w/o qualification to
+Iteration Count - The number of times the header will execute before
+some interesting event happens. Commonly used without qualification to
refer to the iteration count at which the loop exits. Will always be
-one greater than the backedge taken count. (Warning: Preceding
+one greater than the backedge taken count. *Warning*: Preceding
statement is true in the *integer domain*; if you're dealing with fixed
width integers (such as LLVM Values or SCEVs), you need to be cautious
-of overflow when converting one to the other.)
+of overflow when converting one to the other.
+
+It's important to note that the same basic block can play multiple
+roles in the same loop, or in different loops at once. For example, a
+single block can be the header for two nested loops at once, while
+also being an exit block for a sibling loop.
Loop Simplify Form
==================
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