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// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package abi
type InterfaceSwitch struct {
Cache *InterfaceSwitchCache
NCases int
// Array of NCases elements.
// Each case must be a non-empty interface type.
Cases [1]*InterfaceType
}
type InterfaceSwitchCache struct {
Mask uintptr // mask for index. Must be a power of 2 minus 1
Entries [1]InterfaceSwitchCacheEntry // Mask+1 entries total
}
type InterfaceSwitchCacheEntry struct {
// type of source value (a *Type)
Typ uintptr
// case # to dispatch to
Case int
// itab to use for resulting case variable (a *runtime.itab)
Itab uintptr
}
const go122InterfaceSwitchCache = true
func UseInterfaceSwitchCache(goarch string) bool {
if !go122InterfaceSwitchCache {
return false
}
// We need an atomic load instruction to make the cache multithreaded-safe.
// (AtomicLoadPtr needs to be implemented in cmd/compile/internal/ssa/_gen/ARCH.rules.)
switch goarch {
case "amd64", "arm64", "loong64", "mips", "mipsle", "mips64", "mips64le", "ppc64", "ppc64le", "riscv64", "s390x":
return true
default:
return false
}
}
type TypeAssert struct {
Cache *TypeAssertCache
Inter *InterfaceType
CanFail bool
}
type TypeAssertCache struct {
Mask uintptr
Entries [1]TypeAssertCacheEntry
}
type TypeAssertCacheEntry struct {
// type of source value (a *runtime._type)
Typ uintptr
// itab to use for result (a *runtime.itab)
// nil if CanFail is set and conversion would fail.
Itab uintptr
}
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