}
	// R1 op R2 or r1 op constant.
	// op is:
	//	"<<" == 0
	//	">>" == 1
	//	"->" == 2
	//	"@>" == 3
	r1, ok := p.registerReference(name)
	if !ok {
		return 0
	}
	var op int16
	switch p.next().ScanToken {
	case lex.LSH:
		op = 0
	case lex.RSH:
		op = 1
	case lex.ARR:
		op = 2
	case lex.ROT:

// assembler.

package arch

import (
	"cmd/internal/obj"
	"cmd/internal/obj/riscv"
)

// IsRISCV64AMO reports whether the op (as defined by a riscv.A*
// constant) is one of the AMO instructions that requires special
// handling.
func IsRISCV64AMO(op obj.As) bool {
	switch op {
	case riscv.ASCW, riscv.ASCD, riscv.AAMOSWAPW, riscv.AAMOSWAPD, riscv.AAMOADDW, riscv.AAMOADDD,

	}
	return false
}

// IsPPC64CMP reports whether the op (as defined by an ppc64.A* constant) is
// one of the CMP instructions that require special handling.
func IsPPC64CMP(op obj.As) bool {
	switch op {
	case ppc64.ACMP, ppc64.ACMPU, ppc64.ACMPW, ppc64.ACMPWU, ppc64.AFCMPU:
		return true
	}
	return false
}

// IsPPC64NEG reports whether the op (as defined by an ppc64.A* constant) is

// len(src) and len(dst).
func copy(dst, src []Type) int

// The delete built-in function deletes the element with the specified key
// (m[key]) from the map. If m is nil or there is no such element, delete
// is a no-op.
func delete(m map[Type]Type1, key Type)

// The len built-in function returns the length of v, according to its type:
//
//	Array: the number of elements in v.

<pre class="ebnf">
Expression = UnaryExpr | Expression binary_op Expression .
UnaryExpr  = PrimaryExpr | unary_op UnaryExpr .

binary_op  = "||" | "&amp;&amp;" | rel_op | add_op | mul_op .
rel_op     = "==" | "!=" | "&lt;" | "&lt;=" | ">" | ">=" .
add_op     = "+" | "-" | "|" | "^" .
mul_op     = "*" | "/" | "%" | "&lt;&lt;" | "&gt;&gt;" | "&amp;" | "&amp;^" .

unary_op   = "+" | "-" | "!" | "^" | "*" | "&amp;" | "&lt;-" .
</pre>

// MRC or MCR.
func IsARMMRC(op obj.As) bool {
	switch op {
	case arm.AMRC, aMCR: // Note: aMCR is defined in this package.
		return true
	}
	return false
}

// IsARMBFX reports whether the op (as defined by an arm.A* constant) is one the
// BFX-like instructions which are in the form of "op $width, $LSB, (Reg,) Reg".
func IsARMBFX(op obj.As) bool {
	switch op {
	case arm.ABFX, arm.ABFXU, arm.ABFC, arm.ABFI:
		return true

}

// IsLoong64CMP reports whether the op (as defined by an loong64.A* constant) is
// one of the CMP instructions that require special handling.
func IsLoong64CMP(op obj.As) bool {
	switch op {
	case loong64.ACMPEQF, loong64.ACMPEQD, loong64.ACMPGEF, loong64.ACMPGED,
		loong64.ACMPGTF, loong64.ACMPGTD:
		return true
	}
	return false
}

// IsLoong64MUL reports whether the op (as defined by an loong64.A* constant) is

// leading / or ../ elements.
func (r *Reader) Open(name string) (fs.File, error) {
	r.initFileList()

	if !fs.ValidPath(name) {
		return nil, &fs.PathError{Op: "open", Path: name, Err: fs.ErrInvalid}
	}
	e := r.openLookup(name)
	if e == nil {
		return nil, &fs.PathError{Op: "open", Path: name, Err: fs.ErrNotExist}
	}
	if e.isDir {
		return &openDir{e, r.openReadDir(name), 0}, nil
	}
	rc, err := e.file.Open()

func IsARM64TBL(op obj.As) bool {
	switch op {
	case arm64.AVTBL, arm64.AVTBX, arm64.AVMOVQ:
		return true
	}
	return false
}

// IsARM64CASP reports whether the op (as defined by an arm64.A*
// constant) is one of the CASP-like instructions, and its 2nd
// destination is a register pair that require special handling.
func IsARM64CASP(op obj.As) bool {
	switch op {
	case arm64.ACASPD, arm64.ACASPW:

	}
	return false
}

// IsMIPSCMP reports whether the op (as defined by an mips.A* constant) is
// one of the CMP instructions that require special handling.
func IsMIPSCMP(op obj.As) bool {
	switch op {
	case mips.ACMPEQF, mips.ACMPEQD, mips.ACMPGEF, mips.ACMPGED,
		mips.ACMPGTF, mips.ACMPGTD:
		return true
	}
	return false
}

// IsMIPSMUL reports whether the op (as defined by an mips.A* constant) is