35 lines
689 B
Plaintext
35 lines
689 B
Plaintext
C LB+ctrlonceonce+mbonceonce
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(*
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* Result: Never
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*
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* This litmus test demonstrates that lightweight ordering suffices for
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* the load-buffering pattern, in other words, preventing all processes
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* reading from the preceding process's write. In this example, the
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* combination of a control dependency and a full memory barrier are enough
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* to do the trick. (But the full memory barrier could be replaced with
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* another control dependency and order would still be maintained.)
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*)
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{}
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P0(int *x, int *y)
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{
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int r0;
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r0 = READ_ONCE(*x);
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if (r0)
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WRITE_ONCE(*y, 1);
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}
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P1(int *x, int *y)
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{
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int r0;
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r0 = READ_ONCE(*y);
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smp_mb();
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WRITE_ONCE(*x, 1);
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}
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exists (0:r0=1 /\ 1:r0=1)
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