…one `ParameterIndex` struct to index (#3059)

This reverts commit 45e2e59.

This commit creates a 'ParameterProxy' type and 'ParameterIndex' to represent parameters in a consistent way. This is motivated by using 'int' to represent different ways of counting parameters (sometimes offset by 1 for the 'this' parameter, sometimes not offset). ParameterIndex should now be the only type used to index into a method's parameters. ParameterIndex represents the index of the parameter as it is passed to the method in IL (i.e. 'this' is the 0 index in instance methods). ParameterProxy wraps the common convention of a MethodProxy and int to represent a parameter, and now holds a Method and a ParameterIndex to encapsulate a Parameter.

No behavioral changes are expected from this change.

Co-authored-by: Vitek Karas <[email protected]>
Co-authored-by: dotnet-maestro[bot] <42748379+dotnet-maestro[bot]@users.noreply.github.com>

* Update CI status in readme

Co-authored-by: Sven Boemer <[email protected]>

…3073)

Instead of checking every virtual method to see if it should be kept due
to a base method every iteration of the MarkStep pipeline, check each
method only when its relevant state has changed. 

Co-authored-by: Sven Boemer <[email protected]>

…sion (#3091)

…024.5 (#3092)

[main] Update dependencies from dotnet/arcade

Changes to processing of compiler generated methods lead to a state where we don't call constant prop and branch removal in all cases before we mark instructions of the method. This can lead to overmarking

This change fixes this by making sure that the branch removal executes on the method in all cases before we mark instructions of the method.

The change guarantees that all accesses to Body are after the constant prop/branch removal happened on the method.

This does have one possibly negative impact: the issue described in https://github.com/dotnet/linker/issues/2937 is now consistent and happens always.

Added tests.

Note that there's still a whole in analysis of compiler generated code around state machines, see #3087

Basically if there's a local function which is going to be removed due to branch removal and if the body of that method contains code which produces a warning due to generic parameter validation, such warning will always be generated even though it's "dead" code and even if it's suppressed via RUC or similar.

In such case the analysis can't figure out to which method the local function belongs (since the call site has been removed).

… is not marked (#3098)

* Don't mark an override every time the base is abstract, only if the declaring type is also marked
Adds a condition to ShouldMarkOverrideForBase to exit early if the declaring type of the method is not marked.