diff options
| -rw-r--r-- | src/ir/type-updating.h | 31 | ||||
| -rw-r--r-- | src/passes/param-utils.h | 6 |
2 files changed, 30 insertions, 7 deletions
diff --git a/src/ir/type-updating.h b/src/ir/type-updating.h index 151b0d41a..85134da67 100644 --- a/src/ir/type-updating.h +++ b/src/ir/type-updating.h @@ -23,13 +23,30 @@ namespace wasm { -// a class that tracks type dependencies between nodes, letting you -// update types efficiently when removing and altering code. -// altering code can alter types in the following way: -// * removing a break can make a block unreachable, if nothing else -// reaches it -// * altering the type of a child to unreachable can make the parent -// unreachable +// +// A class that tracks type dependencies between nodes, letting you update types +// efficiently when removing and altering code incrementally. +// +// Altering code can alter types beyond the current node in the following ways: +// +// 1. Removing a break can make a block unreachable, if nothing else reaches +// it. +// 2. Altering the type of a child to unreachable can make the parent +// unreachable. +// +// Most passes don't do either of the above and can just do replaceCurrent when +// replacing one thing with another, which is fine as no types need to be +// updated outside of the item being replaced. Passes that do one of the two +// things mentioned need to update types in the IR affected by the change (which +// can include any of the parent nodes, in general) and they have two main ways +// to do so: +// +// * Call ReFinalize() after making all their changes. The IR will be in an +// invalid state while making the changes, and only fixed up at the end by +// ReFinalize(), but often that is good enough. +// * Use this class, TypeUpdater. This lets you update the IR after each +// incremental change that you perform, keeping the IR valid constantly. +// struct TypeUpdater : public ExpressionStackWalker<TypeUpdater, UnifiedExpressionVisitor<TypeUpdater>> { diff --git a/src/passes/param-utils.h b/src/passes/param-utils.h index 10645b230..202c8b007 100644 --- a/src/passes/param-utils.h +++ b/src/passes/param-utils.h @@ -58,6 +58,12 @@ std::unordered_set<Index> getUsedParams(Function* func); // use cases are either to send a single function, or to send a set of functions // that all have the same heap type (and so if they all do not use some // parameter, it can be removed from them all). +// +// This does *not* update the types in call_refs. It is assumed that the caller +// will be updating types, which is simpler as there may be other locations that +// need adjusting and it is easier to do it all in one place. Also, the caller +// can update all the types at once throughout the program after making +// multiple calls to removeParameter(). bool removeParameter(const std::vector<Function*>& funcs, Index index, const std::vector<Call*>& calls, |