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Diffstat (limited to 'chapter05/README.md')
| -rw-r--r-- | chapter05/README.md | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/chapter05/README.md b/chapter05/README.md index cff2798b..a5c6f52f 100644 --- a/chapter05/README.md +++ b/chapter05/README.md @@ -14,7 +14,7 @@ Here is a recap of the nodes introduced in previous chapters: | Node Name | Type | Chapter | Description | Inputs | Value | |------------|----------------|---------|------------------------------------------------|------------------------------------------------------------------|-------------------------------------------------------------------------| -| MultiNode | Abstract class | 4 | A node that has a tuple result | | A tuple | +| Multi | Abstract class | 4 | A node that has a tuple result | | A tuple | | Start | Control | 1 | Start of function, now a MultiNode | An input argument named `arg`. | A tuple with a ctrl token and an `arg` data node | | Proj | ? | 4 | Projection nodes extract values from MultiNode | A MultiNode and index | Result is the extracted value from the input MultiNode at offset index | | Bool | Data | 4 | Represents results of a comparison operator | Two data nodes | Result a comparison, represented as integer value where 1=true, 0=false | @@ -35,7 +35,7 @@ Following new nodes are introduced in this chapter: |-----------|---------|---------|----------------------------------------------------------------------|------------------------------------------------------------------------------------------------|---------------------------------------------------------------| | If | Control | 5 | Represents an `if` condition, sub type of `MultiNode` | A control node and a data predicate node | A tuple of two values, one for true branch, another for false | | Region | Control | 5 | Represents a merge point from multiple control flow | An input for each control flow that is merging | None | -| Phi | ? | 5 | Represents the phi function that picks a value based on control flow | A region control node, and multiple data nodes that provide values from multiple control flows | Result is the extracted value depending on control flow taken | +| Phi | Data | 5 | Represents the phi function that picks a value based on control flow | A region control node, and multiple data nodes that provide values from multiple control flows | Result is the extracted value depending on control flow taken | | Stop | Control | 5 | Represents termination of the program | One or more Return nodes | None | ## Parsing of `If` statement @@ -44,12 +44,12 @@ When we parse an `if` statement, the control flow splits at that point. We must This involves following: -* The `IfNode` is created with the current control token, i.e. the node mapped to `$ctrl`, and the predicate expression as inputs. +* We create an `IfNode` with the current control token, i.e. the node mapped to `$ctrl`, and the `if` predicate expression as inputs. * We add two `ProjNodes` - one for the `True` branch (call if `ifT`), and the other for the `False` branch (call it `ifF`) - these extract values from the tuple result of the `IfNode`. -* We now create a duplicate of the current `ScopeNode`. The duplicated `ScopeNode` must have all the stack levels as the original, and moreover the new node must be a user of all the names that are currently bound. +* We duplicate the current `ScopeNode`. The duplicated `ScopeNode` contains all the stack levels as the original, and moreover the new node is added as a user of all the names that are currently bound. * The original `ScopeNode` is saved. * We set the duplicate `ScopeNode` as current. -* The control token is updated to the `True` projection node `ifT`. +* We set control token to the `True` projection node `ifT`. * We parse the true branch of the `if` statement. * We reset the original `ScopeNode` as current. * We set control token to the `False` projection node `ifF`. @@ -80,7 +80,7 @@ Following shows the graph just before we merge the two branches of the `if` stat * Note the two `ScopeNode`s in the graph. * One has its `$ctrl` pointing to the `True` projection, while the other has `$ctrl` pointing to `False` projection. -* Note that the binding of `a` is to the `Sub` node in the `False` branch, whereas `a` is bound to the `Add` node in the `True` branch. +* Note that `a` is bound to the `Sub` node in the `False` branch, whereas `a` is bound to the `Add` node in the `True` branch. * Thus `a` needs a `Phi` node. ### After merging |