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diff --git a/chapter18/README.md b/chapter18/README.md index 5691059f..7482eafb 100644 --- a/chapter18/README.md +++ b/chapter18/README.md @@ -1,6 +1,6 @@ # Chapter 18: Functions -[Previous: Chapter 17](../chapter17/README.md) | +[Previous: Chapter 17b](../chapter17b/README.md) | [Next: Chapter 19](../chapter19/README.md) @@ -13,7 +13,7 @@ 5. [Graph Visualizer](#graph-visualizer) 6. [Memory across functions](#memory-across-functions) -You can also read [this chapter](https://github.com/SeaOfNodes/Simple/tree/linear-chapter18) in a linear Git revision history on the [linear](https://github.com/SeaOfNodes/Simple/tree/linear) branch and [compare](https://github.com/SeaOfNodes/Simple/compare/linear-chapter17...linear-chapter18) it to the previous chapter. +You can also read [this chapter](https://github.com/SeaOfNodes/Simple/tree/linear-chapter18) in a linear Git revision history on the [linear](https://github.com/SeaOfNodes/Simple/tree/linear) branch and [compare](https://github.com/SeaOfNodes/Simple/compare/linear-chapter17b...linear-chapter18) it to the previous chapter. I hardly know where to begin! So many things changed here, mostly as indirect consequences of supporting functions. @@ -86,6 +86,12 @@ analysis of a hypothetical `call/cc` operation. That is outside our current scope, so for now these are only used in the evaluator. +Parameters use the explicit declaration syntax from +[Chapter 17a](../chapter17a/README.md): `!Point p` allows writes through a fixed +parameter binding, `Point !p` allows reassignment of a read-only reference, +and `int ~limit` fixes a primitive parameter. Inferred `var`/`val` parameters +are not supported. + ## Functions Functions themselves use the same syntax as function types, but filled in: @@ -183,16 +189,19 @@ After a `Call` is a `CallEndNode`, internally abbreviated as `cend`. The `CallEnd` will take the `Call` as an input, and also every *linked* function: functions the call-site *knows* it will call. This will be expanded later to be a conservative approximation to the *Call Graph*, with each `CallEnd` -*linked* to every function it *may* call; if a function is not linked it can not -be called from here. This requires a global analysis (fast, cheap, -incremental, and global), not in this chapter. So for the moment we only -link exact constant functions. +*linked* to every function it *may* call; if a function is not linked it can +not be called from here. This requires a global analysis (fast, cheap, +incremental, and global) which shows up in [Chapter24](../chapter19/README.md), +[SCCP](https://en.wikipedia.org/wiki/Sparse_conditional_constant_propagation). +So for the moment we only link exact constant functions. If a call site is linked to a single function, and that single function is only called by this one call site (its function pointer is only used here, obvious from GVN) then the function inlines in the IR. -`CallEnd`s are followed by projections for Control, Memory and the return value. +[edit note: needs before/after graph of trivial inlining] + +Like `Start`, `CallEnd`s are followed by projections for Control, Memory and the return value. |