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    Types: TextFile
    Names: »B«

└─⟦180fe333a⟧ Bits:30000405 8mm tape, Rational 1000, SW CATALOG, 10_20_0
└─⟦180fe333a⟧ Bits:30000537 8mm tape, Rational 1000, SW Catalog 10_20_0
    └─⟦5cb1d1d7f⟧ »DATA« 
        └─⟦3b1ee7bd8⟧ 
            └─⟦this⟧ 

TextFile

with Instrument;
use Instrument;

-----------------
-- Store Elimination
-----------------

--  This test evaluates a code  improvement  potential  that  results
--  from  the  elimination  of  operations that store values when the
--  opportunity is offered to propagate these values.

--  The optimized  test  procedure  evaluates  two  expressions  that
--  redefine  Global_1 and Global_2.  These variables are immediately
--  redefined using  their  current  values  thereby  allowing  these
--  values to be propagated rather than explicitly stored.

--  The nonoptimized test  procedure  inhibits  the  optimization  by
--  introducing  a  call  to  a  procedure  in  the  basic block that
--  necessitates that Global_1 and Global_2 be  defined  since  their
--  values can no longer be safely propagated.  The final expressions
--  redefining these variables must preclude legitimate optimizations
--  that  may occur when the offered one is not recognized or chosen.
--  Typically this will result in an elimination of redundant  stores
--  by  virtue  of the expression structure where the redefinition of
--  Global_1 and Global_2 is performed without additional stores.

procedure Opsea2 is

    package New_Procs is new Procs (Integer);
    use New_Procs;

    Global_1 : T;
    Global_2 : T;
    Global_3 : T;
    Global_4 : T;
    Global_5 : T;

    procedure Break_Basic_Block is
    begin
        Let (Global_1, Ident (Init / Init));
        Let (Global_2, Ident (Init / Init));
        Let (Global_3, Ident (Init / Init));
        Let (Global_4, Ident (Init / Init));
        Let (Global_5, Ident (Init / Init));
    end Break_Basic_Block;

begin

    Start ("OPSEA2", "Optimization Perf., Store Elim. (test)");
    for I in 1 .. 1000 loop

        Let (Global_1, Ident (Init / Init));
        Let (Global_2, Ident (Init / Init));
        Let (Global_3, Ident (Init / Init));
        Let (Global_4, Ident (Init / Init));
        Let (Global_5, Ident (Init / Init));

        Global_1 := Global_4 + Global_5;
        Global_2 := Global_4 - Global_5;

        --  Break_Basic_Block;         -- included in control version

        Global_1 := Global_3 - Global_1;
        Global_2 := Global_3 + Global_2;

        Break_Basic_Block;         -- included in test version
        Let (Global_1, Ident (Init / Init));
        Let (Global_2, Ident (Init / Init));
        Let (Global_3, Ident (Init / Init));
        Let (Global_4, Ident (Init / Init));
        Let (Global_5, Ident (Init / Init));

    end loop;
    Stop;

end Opsea2;