Misc/abrash-black-book
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Change bold code snippets to inline code blocks

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James Gregory 2013-12-31 17:12:29 +11:00
commit 3c76d884ef
185 changed files with 1772 additions and 1772 deletions
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21-01.md
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@ -114,13 +114,13 @@ mov edx,[ebp-8] ;V-pipe cycle 3 lockstep idle
;V-pipe cycle 4 mov edx,[ebp-8]
```
This commonplace code loses a U-pipe cycle to the AGI caused by **AND
EBX,EBX**, followed by the attempt two instructions later to use EBX to
This commonplace code loses a U-pipe cycle to the AGI caused by `AND
EBX,EBX`, followed by the attempt two instructions later to use EBX to
point to memory. The code loses a V-pipe cycle as well, because lockstep
execution won't let the next V-pipe instruction execute until the paired
U-pipe instruction that suffered the AGI finishes. The solution is to
use **TEST EBX,EBX** instead of **AND; TEST** can't modify EBX, so no
AGI occurs. Sure, **AND EBX,EBX** doesn't modify EBX either, but the
use `TEST EBX,EBX` instead of `AND; TEST` can't modify EBX, so no
AGI occurs. Sure, `AND EBX,EBX` doesn't modify EBX either, but the
Pentium doesn't know that, so it has to insert the AGI.
![**Figure 21.2**  *An AGI can cost as many as 3 cycles.*](images/21-02.jpg)