From 6b4ed4d07831f738755cb8162eff24d6d9a695fc Mon Sep 17 00:00:00 2001 From: Symious <14933944+symious@users.noreply.github.com> Date: Thu, 10 Sep 2026 04:50:36 +0800 Subject: Docs: Proj is not always a data node (#250) The node recap tables in chapters 4 and 5 classify `Proj` as "Data", but `ProjNode.isCFG()` has returned true for control projections since chapter 4: ch4: return _idx==0; ch5+: return _idx==0 || ctrl() instanceof IfNode; So `Proj#0` off `Start` is a control node, and from chapter 5 both projections off an `If` are too -- which is exactly why the dominator walk in `IfNode.compute()` can step through them. Change the Type column to "Data / Control" and add a note under each table pointing at `isCFG()`. Table alignment is unchanged: "Data / Control" is the same width as "Abstract class". Docs-only change. Co-authored-by: Claude Opus 5 --- chapter04/README.md | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'chapter04') diff --git a/chapter04/README.md b/chapter04/README.md index a7b223b4..272d0b8d 100644 --- a/chapter04/README.md +++ b/chapter04/README.md @@ -39,10 +39,13 @@ Following are revised or new nodes |-----------|----------------|------------------------------------------------|-----------------------|----------------------------------------------------------------------------| | MultiNode | Abstract class | A node that has a tuple result | | A tuple | | Start | Control | Start of function, now a MultiNode | | A tuple with a ctrl token and an `arg` data node | -| Proj | Data | Projection nodes extract values from MultiNode | A MultiNode and index | Result is the extracted value from the input MultiNode at offset index | +| Proj | Data / Control | Projection nodes extract values from MultiNode | A MultiNode and index | Result is the extracted value from the input MultiNode at offset index | | Bool | Data | Represents results of a comparison operator | Two data nodes | Result is a comparison, represented as integer value where 1=true, 0=false | | Not | Data | Logical not | One data node | Result converts 0 to 1 and vice versa | +> A `Proj` is a control node when it projects the control slot: `Proj#0` off `Start`. +> Every other projection is a data node. See `ProjNode.isCFG()`. + Below is our list of Nodes from [Chapter 3](../chapter03/README.md): | Node Name | Type | Description | Inputs | Value | -- cgit v1.2.3