Another Example

Here's another example...
More on Branch Predication and Control Speculation

if a[i].ptr != 0
b[i] = a[i].l;
else
b[i] = a[i].r;
i = i + 1;

The above code segment is sectioned into four basic blocks in most traditional architectures.

Rather than use four blocks for execution, the IA-64 organizes the code as such...

The processor will begin to execute both the <p1> and <p2> pathes and when the branch has been determined, one path will be killed. For control speculation, the following code would be be organized as such:

This unique method of scheduling allows the memory latency to be hidden behind the computation of the if statement.

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