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Annotation of coherent/a/usr/man/ALL/registervariab, revision 1.1

1.1     ! root        1: 
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        !             3: register variable           Definition          register variable
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        !             8: register is a C  storage class.  A register declaration tells the
        !             9: compiler to try to keep the  defined local data item in a machine
        !            10: register.   Under the  COHERENT C  compiler, the  iinntt ffoooo  can be
        !            11: declared to be a register variable with the following statement:
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        !            13: 
        !            14:         register int foo;
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        !            17: COHERENT places  the first two  register variables declared  in a
        !            18: function into  registers SI  and DI if  the variable type  is ap-
        !            19: propriate, i.e., int or SMALL-model pointer.  Subsequent register
        !            20: declarations are  ignored, because no registers  are left to hold
        !            21: them.   Note  because  of  this  fact,  declaring more  than  two
        !            22: register variables may slow processing rather than speed it.
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        !            24: By definition of the  C language, registers have no addresses, so
        !            25: you cannot  pass the address of register  variable as an argument
        !            26: to a function.  For  example, the following code will generate an
        !            27: error message when compiled:
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        !            29: 
        !            30:         register int i;
        !            31:           . . .
        !            32:         dosomething(&i);        /* WRONG */
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        !            34: 
        !            35: This rule applies whether or not the variable is actually kept in
        !            36: a register.
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        !            38: Placing  heavily-used local  variables into  registers  often im-
        !            39: proves  performance,   but  in  some   cases  declaring  register
        !            40: variables can degrade performance somewhat.
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        !            42: ***** See Also *****
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        !            44: auto, definitions, extern, static, storage class
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        !            64: COHERENT Lexicon                                           Page 1
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