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// Package platform includes runtime-specific code needed for the compiler or otherwise.
//
// Note: This is a dependency-free alternative to depending on parts of Go's x/sys.
// See /RATIONALE.md for more context.
package platform
import (
"runtime"
)
// archRequirementsVerified is set by platform-specific init to true if the platform is supported
var archRequirementsVerified bool
// CompilerSupported is exported for tests and includes constraints here and also the assembler.
func CompilerSupported() bool {
switch runtime.GOOS {
case "darwin", "windows", "linux", "freebsd":
default:
return false
}
return archRequirementsVerified
}
// MmapCodeSegment copies the code into the executable region and returns the byte slice of the region.
//
// See https://man7.org/linux/man-pages/man2/mmap.2.html for mmap API and flags.
func MmapCodeSegment(size int) ([]byte, error) {
if size == 0 {
panic("BUG: MmapCodeSegment with zero length")
}
if runtime.GOARCH == "amd64" {
return mmapCodeSegmentAMD64(size)
} else {
return mmapCodeSegmentARM64(size)
}
}
// RemapCodeSegment reallocates the memory mapping of an existing code segment
// to increase its size. The previous code mapping is unmapped and must not be
// reused after the function returns.
//
// This is similar to mremap(2) on linux, and emulated on platforms which do not
// have this syscall.
//
// See https://man7.org/linux/man-pages/man2/mremap.2.html
func RemapCodeSegment(code []byte, size int) ([]byte, error) {
if size < len(code) {
panic("BUG: RemapCodeSegment with size less than code")
}
if code == nil {
return MmapCodeSegment(size)
}
if runtime.GOARCH == "amd64" {
return remapCodeSegmentAMD64(code, size)
} else {
return remapCodeSegmentARM64(code, size)
}
}
// MunmapCodeSegment unmaps the given memory region.
func MunmapCodeSegment(code []byte) error {
if len(code) == 0 {
panic("BUG: MunmapCodeSegment with zero length")
}
return munmapCodeSegment(code)
}
// mustMunmapCodeSegment panics instead of returning an error to the
// application.
//
// # Why panic?
//
// It is less disruptive to the application to leak the previous block if it
// could be unmapped than to leak the new block and return an error.
// Realistically, either scenarios are pretty hard to debug, so we panic.
func mustMunmapCodeSegment(code []byte) {
if err := munmapCodeSegment(code); err != nil {
panic(err)
}
}
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