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Diffstat (limited to 'chapter07/README.md')
| -rw-r--r-- | chapter07/README.md | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/chapter07/README.md b/chapter07/README.md index 29f08b5f..d701278a 100644 --- a/chapter07/README.md +++ b/chapter07/README.md @@ -77,15 +77,15 @@ In [Chapter 8](../chapter08) we will implement a "lazy phi" approach that create ## New Node Types Our list of nodes remains the same as in [Chapter 5](../chapter05/README.md), however, we create a subtype of `Region` named `Loop` to better -encapsulate some of the additional logic required. A key aspect of this is to temporarily disable peepholes of the `Region` and any phis -created until we complete parsing the loop body. This is because our phis are not fully constructed until the loop end. +encapsulate some of the additional logic required. Loop and Phi peepholes defer rewrites that need the back edge +until we complete parsing the loop body. Other nodes continue to optimize normally. ## Detailed Steps 1. We start by creating a new subclass of `Region`, the `Loop`. The `Loop` gets two control inputs, the first is the entry point, i.e. the current binding to `$ctrl`, and second (`null`) is a placeholder for the back edge that is - set after loop is parsed. The absence of a back edge is used as an indicator to switch off peepholes of the region and - associated phis. + set after the loop is parsed. A missing back edge marks the Loop and associated Phis as incomplete, + so their peepholes wait for the inputs needed by each rewrite. ```java ctrl(new LoopNode(ctrl(),null).peephole()); |