Currently `avo` uses `BP` as a standard general-purpose register. However, `BP` is used for the frame pointer and should be callee-save. Under some circumstances, the Go assembler will do this automatically, but not always. At the moment `avo` can produce code that clobbers the `BP` register. Since Go 1.16 this code will also fail a new `go vet` check.
This PR provides a (currently sub-optimal) fix for the issue. It introduces an `EnsureBasePointerCalleeSaved` pass which will check if the base pointer is written to by a function, and if so will artificially ensure that the function has a non-zero frame size. This will trigger the Go assembler to automatically save and restore the BP register.
In addition, we update the `asmdecl` tool to `asmvet`, which includes the `framepointer` vet check.
Updates #156
Issue #77 pointed out that in the case of named array types, the gotypes Components type fails to recognize the underlying type as an array. In fact this problem was more widespread. This diff fixes the missing calls to Underlying() and adds some test cases.
Fixes#77
Provides a method on `gotypes.Component` to allow pointer dereference. This will enable `gotypes` helpers to be used with struct pointer arguments, for example.
Updates #53Fixes#54
