Source file src/internal/abi/abi.go
Documentation: internal/abi
1 // Copyright 2020 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 package abi 6 7 import "unsafe" 8 9 // RegArgs is a struct that has space for each argument 10 // and return value register on the current architecture. 11 // 12 // Assembly code knows the layout of the first two fields 13 // of RegArgs. 14 // 15 // RegArgs also contains additional space to hold pointers 16 // when it may not be safe to keep them only in the integer 17 // register space otherwise. 18 type RegArgs struct { 19 Ints [IntArgRegs]uintptr // untyped integer registers 20 Floats [FloatArgRegs]uint64 // untyped float registers 21 22 // Fields above this point are known to assembly. 23 24 // Ptrs is a space that duplicates Ints but with pointer type, 25 // used to make pointers passed or returned in registers 26 // visible to the GC by making the type unsafe.Pointer. 27 Ptrs [IntArgRegs]unsafe.Pointer 28 29 // ReturnIsPtr is a bitmap that indicates which registers 30 // contain or will contain pointers on the return path from 31 // a reflectcall. The i'th bit indicates whether the i'th 32 // register contains or will contain a valid Go pointer. 33 ReturnIsPtr IntArgRegBitmap 34 } 35 36 // IntArgRegBitmap is a bitmap large enough to hold one bit per 37 // integer argument/return register. 38 type IntArgRegBitmap [(IntArgRegs + 7) / 8]uint8 39 40 // Set sets the i'th bit of the bitmap to 1. 41 func (b *IntArgRegBitmap) Set(i int) { 42 b[i/8] |= uint8(1) << (i % 8) 43 } 44 45 // Get returns whether the i'th bit of the bitmap is set. 46 // 47 // nosplit because it's called in extremely sensitive contexts, like 48 // on the reflectcall return path. 49 // 50 //go:nosplit 51 func (b *IntArgRegBitmap) Get(i int) bool { 52 return b[i/8]&(uint8(1)<<(i%8)) != 0 53 } 54 55 // FuncPC* intrinsics. 56 // 57 // CAREFUL: In programs with plugins, FuncPC* can return different values 58 // for the same function (because there are actually multiple copies of 59 // the same function in the address space). To be safe, don't use the 60 // results of this function in any == expression. It is only safe to 61 // use the result as an address at which to start executing code. 62 63 // FuncPCABI0 returns the entry PC of the function f, which must be a 64 // direct reference of a function defined as ABI0. Otherwise it is a 65 // compile-time error. 66 // 67 // Implemented as a compile intrinsic. 68 func FuncPCABI0(f interface{}) uintptr 69 70 // FuncPCABIInternal returns the entry PC of the function f. If f is a 71 // direct reference of a function, it must be defined as ABIInternal. 72 // Otherwise it is a compile-time error. If f is not a direct reference 73 // of a defined function, it assumes that f is a func value. Otherwise 74 // the behavior is undefined. 75 // 76 // Implemented as a compile intrinsic. 77 func FuncPCABIInternal(f interface{}) uintptr 78