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|
// Package attr provides attributes for text and data sections.
package attr
import (
"fmt"
"math/bits"
"strings"
)
// Attribute represents TEXT or DATA flags.
type Attribute uint16
// Reference: https://github.com/golang/go/blob/aafe257390cc9048e8b5df898fabd79a9e0d4c39/src/runtime/textflag.h#L11-L37
//
// // Don't profile the marked routine. This flag is deprecated.
// #define NOPROF 1
// // It is ok for the linker to get multiple of these symbols. It will
// // pick one of the duplicates to use.
// #define DUPOK 2
// // Don't insert stack check preamble.
// #define NOSPLIT 4
// // Put this data in a read-only section.
// #define RODATA 8
// // This data contains no pointers.
// #define NOPTR 16
// // This is a wrapper function and should not count as disabling 'recover'.
// #define WRAPPER 32
// // This function uses its incoming context register.
// #define NEEDCTXT 64
// // Allocate a word of thread local storage and store the offset from the
// // thread local base to the thread local storage in this variable.
// #define TLSBSS 256
// // Do not insert instructions to allocate a stack frame for this function.
// // Only valid on functions that declare a frame size of 0.
// // TODO(mwhudson): only implemented for ppc64x at present.
// #define NOFRAME 512
// // Function can call reflect.Type.Method or reflect.Type.MethodByName.
// #define REFLECTMETHOD 1024
// // Function is the top of the call stack. Call stack unwinders should stop
// // at this function.
// #define TOPFRAME 2048
//
const (
NOPROF Attribute = 1 << iota
DUPOK
NOSPLIT
RODATA
NOPTR
WRAPPER
NEEDCTXT
_
TLSBSS
NOFRAME
REFLECTMETHOD
TOPFRAME
)
// Asm returns a representation of the attributes in assembly syntax. This may use macros from "textflags.h"; see ContainsTextFlags() to determine if this header is required.
func (a Attribute) Asm() string {
parts, rest := a.split()
if len(parts) == 0 || rest != 0 {
parts = append(parts, fmt.Sprintf("%d", rest))
}
return strings.Join(parts, "|")
}
// ContainsTextFlags returns whether the Asm() representation requires macros in "textflags.h".
func (a Attribute) ContainsTextFlags() bool {
flags, _ := a.split()
return len(flags) > 0
}
// split splits a into known flags and any remaining bits.
func (a Attribute) split() ([]string, Attribute) {
var flags []string
var rest Attribute
for a != 0 {
i := uint(bits.TrailingZeros16(uint16(a)))
bit := Attribute(1) << i
if flag := attrname[bit]; flag != "" {
flags = append(flags, flag)
} else {
rest |= bit
}
a ^= bit
}
return flags, rest
}
var attrname = map[Attribute]string{
NOPROF: "NOPROF",
DUPOK: "DUPOK",
NOSPLIT: "NOSPLIT",
RODATA: "RODATA",
NOPTR: "NOPTR",
WRAPPER: "WRAPPER",
NEEDCTXT: "NEEDCTXT",
TLSBSS: "TLSBSS",
NOFRAME: "NOFRAME",
REFLECTMETHOD: "REFLECTMETHOD",
TOPFRAME: "TOPFRAME",
}
|
