P4::DoResetHeaders Class Reference

Explicitly invalidate uninitialized header variables. More...

Inheritance diagram for P4::DoResetHeaders:

Public Member Functions
	DoResetHeaders (const TypeMap *typeMap)
const IR::Node *	postorder (IR::Declaration_Variable *decl) override
const IR::Node *	postorder (IR::P4Control *control) override
const IR::Node *	postorder (IR::ParserState *state) override

Static Public Member Functions
static void	generateResets (const TypeMap *typeMap, const IR::Type *type, const IR::Expression *expr, IR::Vector< IR::StatOrDecl > *resets)

Detailed Description

Explicitly invalidate uninitialized header variables.

A local uninitialized variable that represents a header must be initialized to invalid. For example:

state X {
    H h;
    p.extract(h);
}

becomes

state X {
    H h;
    h.setInvalid();
    p.extract(h);
}

This pass also handles header fields in variables of derived types, like structs and unions.

Precondition

An up-to-date TypeMap.

Postcondition

Uninitialized header variables have explicit statements that invalidate those headers.