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Add description of tasking statements
redline.sh is a script to generate a redlined document
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‎cplexts.tex

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\usepackage[normalem]{ulem} % for underlining and strikeout
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\usepackage{underscore} % to simplify use of underscores
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\usepackage{verbatim} % for code font
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\usepackage{xspace} % to simplify a macro that expands to text
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\usepackage{xspace} % to simplify macros that expand to text
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\makeindex
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\setcounter{secnumdepth}{6}
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\setcounter{tocdepth}{6} % increase to check outline structure
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\setcounter{tocdepth}{2} % practical TOC size
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\setcounter{tocdepth}{6} % uncomment to check outline structure
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% These macros are from the WG21 standard source.
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\input{macros}
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% These parameters, and the documentclass options,
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% are about document identification and overall formatting.
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\newcommand{\cplexts}{$CPLEXTS$}
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\renewcommand{\extrahead}{2014-06-24}
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\renewcommand{\extrahead}{2014-08-13}
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\standard{\cplexts}
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\yearofedition{2016}
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\languageofedition{(E)}
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\include{parallelloop}
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\include{spawning}
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\include{loopparameter}
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%\include{samples}

‎loopparameter.tex

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each iteration should be assumed to execute
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in approximately the same amount of time.
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A loop with an unbalanced workload
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should be assumed to have iterations taking a random amount of time.
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should be assumed to have iterations
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taking widely varying amounts of time.
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\begin{note}
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This parameter is semantically a statement about the associated loop,

‎redline.sh

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rm -f ../old
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git checkout-index -f -a --prefix=../old/
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latexdiff-so --flatten ../old/cplexts.tex cplexts.tex >cplexts-diff.tex

‎spawning.tex

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\clause{Spawning tasks}
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\sclause{Task statements}
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\pnum
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The grammar of a statement (6.8, paragraph 1)
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\begin{cpp}
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(clause 6, paragraph 1)
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\end{cpp}
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is modified to add task-statement as a new alternative.
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\ssclause*{Syntax}
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\begin{bnf}
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\nontermdef{task-statement}
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\br
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task-block-statement
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\br
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task-spawn-statement
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\br
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task-sync-statement
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\br
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task-call-statement
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\end{bnf}
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\sclause{The task block statement}
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\ssclause*{Syntax}
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\begin{bnf}
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\nontermdef{task-block-statement}
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\br
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\terminal{_Task_parallel} \terminal{_Block} compound-statement
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\end{bnf}
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\ssclause*{Semantics}
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\pnum
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Defines a task block, within which tasks can be spawned.
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At the end of the contained compound statement,
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all child tasks spawned directly or indirectly
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within the compound statement are
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\defn{joined}:
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the statement following the task block is not executed
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until all of the child tasks complete.
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\pnum
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For a given statement, the
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\defn{associated task block}
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is defined as follows.
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For a statement within a task spawn statement,
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there is no associated task block,
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except within a nested task block statement.
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For a statement within a task block statement,
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the associated task block is the smallest enclosing task block statement.
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Otherwise, for a statement within the body of a function
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declared with the spawning function specifier,
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the associated task block is the same as it was
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at the point of the task spawning call statement
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that invoked the spawning function.
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For statements in other contexts,
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there is no associated task block.
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\footnote{EN:
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Should a parallel loop implicitly establish its own task block?
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}
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\begin{note}
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Task blocks can be nested lexically and/or dynamically.
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Determination of the associated task block is a hybrid process:
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lexically within a function,
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and dynamically across calls to spawning functions.%
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\footnote{DFEP:
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In Cilk, this determination can be done entirely lexically.
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In OpenMP, this determination can be done entirely dynamically.
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}
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Code designated for execution in another thread
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by means other than a task statement
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(e.g. using
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\tcode{thrd_create})
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is not part of any task block.
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\end{note}
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\sclause{The task spawn statement}
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\ssclause*{Syntax}
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\begin{bnf}
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\nontermdef{task-spawn-statement}
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\br
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\terminal{_Task_parallel} \terminal{_Spawn} compound-statement
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\end{bnf}
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\ssclause*{Constraints}
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\pnum
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A task spawn statement shall have an associated task block.
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\ssclause*{Semantics}
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\pnum
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Creates a child task of the associated task block
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of the task spawn statement,
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in which the contained compound statement is executed.
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The execution of the task is unsequenced
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with respect to the statements of the associated task block
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following the spawn statement.
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The completion of the task synchronizes
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with the completion of the associated task block,
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or with the next execution of a sync statement
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within the associated task block.
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\sclause{The task sync statement}
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\ssclause*{Syntax}
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\begin{bnf}
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\nontermdef{task-sync-statement}
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\br
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\terminal{_Task_parallel} \terminal{_Sync} \terminal{;}
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\end{bnf}
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\ssclause*{Constraints}
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\pnum
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A task sync statement shall have an associated task block.
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\ssclause*{Semantics}
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\pnum
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Joins all child tasks of the associated task block
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of the task sync statement.
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\sclause{The task spawning call statement}
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\ssclause*{Syntax}
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\begin{bnf}
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\nontermdef{task-call-statement}
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\br
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\terminal{_Task_parallel} \terminal{_Call} expression-statement
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\footnote{EN:
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Using the same keyword pair
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for the statement prefix and the function specifier
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introduces a case where three tokens of lookahead
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(and hopefully no more)
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are sometimes needed
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to disambiguate a declaration from a statement.
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Is this what we want?
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}
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\end{bnf}
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\ssclause*{Constraints}
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\pnum
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A task spawning call statement shall have an associated task block.
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\ssclause*{Semantics}
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\pnum
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The contained expression statement is executed normally.
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Any called spawning function is allowed to spawn tasks;
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any such tasks are associated with the associated task block
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of the task spawning call statement,
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and are unsequenced with respect to the statements of the task block
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following the task spawning call statement.
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\sclause{The spawning function specifier}
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\ssclause*{Syntax}
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\pnum
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A new alternative is added to the grammar of function specifier
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(6.7.4 paragraph 1):
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\begin{bnf}
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\nontermdef{function-specifier}
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\br
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\terminal{_Task_parallel} \terminal{_Call}
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\end{bnf}
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\ssclause*{Constraints}
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\pnum
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If a spawning function specifier appears
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on any declaration of a function,
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it shall appear on every declaration of that function.
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A function declared with a spawning function specifier
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shall be called only from a task spawning call statement.
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\footnote{EN:
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Is a spawning function specifier part of the function's type?
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If so, are function-pointer conversions allowed?
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}

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