type volatileCopy struct {
			src *Value // address of original volatile value
			tmp *Value // address of temporary we've copied the volatile value into
		}
		var volatiles []volatileCopy

		if !(f.ABIDefault == f.ABI1 && len(f.Config.intParamRegs) >= 3) {
			// We don't need to do this if the calls we're going to do take
			// all their arguments in registers.
			// 3 is the magic number because it covers wbZero, wbMove, cgoCheckMemmove.

	specialRegMask regMask        // special register mask
	intParamRegs   []int8         // register numbers of integer param (in/out) registers
	floatParamRegs []int8         // register numbers of floating param (in/out) registers
	ABI1           *abi.ABIConfig // "ABIInternal" under development // TODO change comment when this becomes current
	ABI0           *abi.ABIConfig
	GCRegMap       []*Register // garbage collector register map, by GC register index

	return (b.Kind == BlockRet || b.Kind == BlockRetJmp) && b.Controls[0] != nil && b.Controls[0].Op == OpMakeResult
}

type Abi1RO uint8 // An offset within a parameter's slice of register indices, for abi1.

// A registerCursor tracks which register is used for an Arg or regValues, or a piece of such.
type registerCursor struct {
	storeDest   *Value // if there are no register targets, then this is the base of the store.

func abiForFunc(fn *ir.Func, abi0, abi1 *abi.ABIConfig) *abi.ABIConfig {
	if buildcfg.Experiment.RegabiArgs {
		// Select the ABI based on the function's defining ABI.
		if fn == nil {
			return abi1
		}
		switch fn.ABI {
		case obj.ABI0:
			return abi0
		case obj.ABIInternal:
			// TODO(austin): Clean up the nomenclature here.
			// It's not clear that "abi1" is ABIInternal.
			return abi1
		}

	ruleMatches    map[string]int // number of times countRule was called during compilation for any given string
	ABI0           *abi.ABIConfig // A copy, for no-sync access
	ABI1           *abi.ABIConfig // A copy, for no-sync access
	ABISelf        *abi.ABIConfig // ABI for function being compiled
	ABIDefault     *abi.ABIConfig // ABI for rtcall and other no-parsed-signature/pragma functions.

		extReader:            extReader,
		symsByName:           [2]map[string]Sym{make(map[string]Sym, 80000), make(map[string]Sym, 50000)}, // preallocate ~2MB for ABI0 and ~1MB for ABI1 symbols
		objByPkg:             make(map[string]uint32),
		sub:                  make(map[Sym]Sym),
		dynimplib:            make(map[Sym]string),
		dynimpvers:           make(map[Sym]string),