Changeset 63aea5a


Ignore:
Timestamp:
Mar 6, 2020, 1:45:01 PM (20 months ago)
Author:
Peter A. Buhr <pabuhr@…>
Branches:
arm-eh, jacob/cs343-translation, jenkins-sandbox, master, new-ast, new-ast-unique-expr
Children:
ca7949b
Parents:
42a99b0
Message:

continue updating storage-management section

File:
1 edited

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  • doc/user/user.tex

    r42a99b0 r63aea5a  
    1111%% Created On       : Wed Apr  6 14:53:29 2016
    1212%% Last Modified By : Peter A. Buhr
    13 %% Last Modified On : Thu Mar  5 12:09:42 2020
    14 %% Update Count     : 3885
     13%% Last Modified On : Fri Mar  6 13:34:52 2020
     14%% Update Count     : 3924
    1515%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    1616
     
    66216621An array may be filled, resized, or aligned.
    66226622\end{description}
    6623 \VRef[Table]{t:AllocationVersusCapabilities} shows allocation routines supporting different combinations of storage-management capabilities:
     6623\VRef[Table]{t:AllocationVersusCapabilities} shows allocation routines supporting different combinations of storage-management capabilities.
    66246624\begin{table}
    66256625\centering
     6626\begin{minipage}{0.75\textwidth}
    66266627\begin{tabular}{@{}r|l|l|l|l|l@{}}
    66276628\multicolumn{1}{c}{}&           & \multicolumn{1}{c|}{fill}     & resize        & alignment     & array \\
     
    66316632                & ©realloc©                     & copy                  & yes           & no            & no    \\
    66326633                & ©memalign©            & no                    & no            & yes           & no    \\
    6633                 & ©aligned_alloc©       & no                    & no            & yes           & no    \\
     6634                & ©aligned_alloc©\footnote{Same as ©memalign© but size is an integral multiple of alignment, which is universally ignored.}
     6635                                                        & no                    & no            & yes           & no    \\
    66346636                & ©posix_memalign©      & no                    & no            & yes           & no    \\
     6637                & ©valloc©                      & no                    & no            & yes (page size)& no   \\
     6638                & ©pvalloc©\footnote{Same as ©valloc© but rounds size to multiple of page size.}
     6639                                                        & no                    & no            & yes (page size)& no   \\
    66356640\hline
    66366641\CFA    & ©cmemalign©           & yes (0 only)  & no            & yes           & yes   \\
    66376642                & ©realloc©                     & copy                  & yes           & yes           & no    \\
    6638                 & ©alloc©                       & no                    & no            & no            & no    \\
    6639                 & ©alloc©                       & copy                  & no/yes        & no            & yes   \\
    6640                 & ©alloc©                       & no/copy/yes   & no/yes        & no            & yes   \\
    6641                 & ©alloc_set©           & no/yes                & no            & yes           & yes   \\
    6642                 & ©alloc_align©         & no/yes                & no            & yes           & yes   \\
    6643                 & ©alloc_align_set©     & no/yes                & no            & yes           & yes   \\
     6643                & ©alloc©                       & no                    & yes           & no            & yes   \\
     6644                & ©alloc_set©           & yes                   & yes           & no            & yes   \\
     6645                & ©alloc_align©         & no                    & yes           & yes           & yes   \\
     6646                & ©alloc_align_set©     & yes                   & yes           & yes           & yes   \\
    66446647\end{tabular}
     6648\end{minipage}
    66456649\caption{Allocation Routines versus Storage-Management Capabilities}
    66466650\label{t:AllocationVersusCapabilities}
    66476651\end{table}
     6652
     6653\CFA memory management extends the type safety of all allocations by using the type of the left-hand-side type to determine the allocation size and return a matching type for the new storage.
     6654Type-safe allocation is provided for all C allocation routines and new \CFA allocation routines, \eg in
     6655\begin{cfa}
     6656int * ip = (int *)malloc( sizeof(int) );                §\C{// C}§
     6657int * ip = malloc();                                                    §\C{// \CFA type-safe version of C malloc}§
     6658int * ip = alloc();                                                             §\C{// \CFA type-safe uniform alloc}§
     6659\end{cfa}
     6660the latter two allocations determine the allocation size from the type of ©p© (©int©) and cast the pointer to the allocated storage to ©int *©.
     6661
     6662\CFA memory management extends allocation safety by implicitly honouring all alignment requirements, \eg in
     6663\begin{cfa}
     6664struct S { int i; } __attribute__(( aligned( 128 ) )); // cache-line alignment
     6665S * sp = malloc();                                                              §\C{// honour type alignment}§
     6666\end{cfa}
     6667the storage allocation is implicitly aligned to 128 rather than the default 16.
     6668The alignment check is performed at compile time so there is no runtime cost.
    66486669
    66496670\CFA memory management extends the resize capability with the notion of \newterm{sticky properties}.
     
    66526673Without sticky properties it is dangerous to use ©realloc©, resulting in an idiom of manually performing the reallocation to maintain correctness.
    66536674
     6675\CFA memory management extends allocation to support constructors for initialization of allocated storage, \eg in
     6676\begin{cfa}
     6677struct S { int i; };                                                    §\C{// cache-line aglinment}§
     6678void ?{}( S & s, int i ) { s.i = i; }
     6679// assume ?|? operator for printing an S
     6680
     6681S & sp = *®new®( 3 );                                                   §\C{// call constructor after allocation}§
     6682sout | sp.i;
     6683®delete®( &sp );
     6684
     6685S * spa = ®anew®( 10, 5 );                                              §\C{// allocate array and initialize each array element}§
     6686for ( i; 10 ) sout | spa[i] | nonl;
     6687sout | nl;
     6688®adelete®( 10, spa );
     6689\end{cfa}
     6690Allocation routines ©new©/©anew© allocate a variable/array and initialize storage using the allocated type's constructor.
     6691Note, the matching deallocation routines ©delete©/©adelete©.
    66546692
    66556693\leavevmode
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