mirror of
https://github.com/superseriousbusiness/gotosocial.git
synced 2025-10-30 21:02:26 -05:00
1185 lines
29 KiB
Go
1185 lines
29 KiB
Go
// Copyright 2018 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package wasm
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import (
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"bytes"
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"github.com/twitchyliquid64/golang-asm/obj"
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"github.com/twitchyliquid64/golang-asm/objabi"
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"github.com/twitchyliquid64/golang-asm/sys"
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"encoding/binary"
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"fmt"
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"io"
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"math"
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)
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var Register = map[string]int16{
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"SP": REG_SP,
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"CTXT": REG_CTXT,
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"g": REG_g,
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"RET0": REG_RET0,
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"RET1": REG_RET1,
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"RET2": REG_RET2,
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"RET3": REG_RET3,
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"PAUSE": REG_PAUSE,
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"R0": REG_R0,
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"R1": REG_R1,
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"R2": REG_R2,
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"R3": REG_R3,
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"R4": REG_R4,
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"R5": REG_R5,
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"R6": REG_R6,
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"R7": REG_R7,
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"R8": REG_R8,
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"R9": REG_R9,
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"R10": REG_R10,
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"R11": REG_R11,
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"R12": REG_R12,
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"R13": REG_R13,
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"R14": REG_R14,
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"R15": REG_R15,
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"F0": REG_F0,
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"F1": REG_F1,
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"F2": REG_F2,
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"F3": REG_F3,
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"F4": REG_F4,
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"F5": REG_F5,
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"F6": REG_F6,
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"F7": REG_F7,
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"F8": REG_F8,
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"F9": REG_F9,
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"F10": REG_F10,
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"F11": REG_F11,
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"F12": REG_F12,
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"F13": REG_F13,
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"F14": REG_F14,
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"F15": REG_F15,
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"F16": REG_F16,
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"F17": REG_F17,
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"F18": REG_F18,
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"F19": REG_F19,
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"F20": REG_F20,
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"F21": REG_F21,
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"F22": REG_F22,
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"F23": REG_F23,
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"F24": REG_F24,
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"F25": REG_F25,
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"F26": REG_F26,
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"F27": REG_F27,
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"F28": REG_F28,
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"F29": REG_F29,
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"F30": REG_F30,
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"F31": REG_F31,
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"PC_B": REG_PC_B,
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}
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var registerNames []string
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func init() {
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obj.RegisterRegister(MINREG, MAXREG, rconv)
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obj.RegisterOpcode(obj.ABaseWasm, Anames)
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registerNames = make([]string, MAXREG-MINREG)
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for name, reg := range Register {
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registerNames[reg-MINREG] = name
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}
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}
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func rconv(r int) string {
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return registerNames[r-MINREG]
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}
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var unaryDst = map[obj.As]bool{
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ASet: true,
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ATee: true,
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ACall: true,
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ACallIndirect: true,
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ACallImport: true,
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ABr: true,
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ABrIf: true,
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ABrTable: true,
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AI32Store: true,
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AI64Store: true,
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AF32Store: true,
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AF64Store: true,
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AI32Store8: true,
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AI32Store16: true,
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AI64Store8: true,
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AI64Store16: true,
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AI64Store32: true,
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ACALLNORESUME: true,
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}
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var Linkwasm = obj.LinkArch{
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Arch: sys.ArchWasm,
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Init: instinit,
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Preprocess: preprocess,
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Assemble: assemble,
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UnaryDst: unaryDst,
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}
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var (
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morestack *obj.LSym
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morestackNoCtxt *obj.LSym
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gcWriteBarrier *obj.LSym
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sigpanic *obj.LSym
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sigpanic0 *obj.LSym
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deferreturn *obj.LSym
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jmpdefer *obj.LSym
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)
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const (
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/* mark flags */
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WasmImport = 1 << 0
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)
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func instinit(ctxt *obj.Link) {
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morestack = ctxt.Lookup("runtime.morestack")
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morestackNoCtxt = ctxt.Lookup("runtime.morestack_noctxt")
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gcWriteBarrier = ctxt.Lookup("runtime.gcWriteBarrier")
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sigpanic = ctxt.LookupABI("runtime.sigpanic", obj.ABIInternal)
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sigpanic0 = ctxt.LookupABI("runtime.sigpanic", 0) // sigpanic called from assembly, which has ABI0
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deferreturn = ctxt.LookupABI("runtime.deferreturn", obj.ABIInternal)
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// jmpdefer is defined in assembly as ABI0, but what we're
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// looking for is the *call* to jmpdefer from the Go function
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// deferreturn, so we're looking for the ABIInternal version
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// of jmpdefer that's called by Go.
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jmpdefer = ctxt.LookupABI(`"".jmpdefer`, obj.ABIInternal)
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}
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func preprocess(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) {
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appendp := func(p *obj.Prog, as obj.As, args ...obj.Addr) *obj.Prog {
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if p.As != obj.ANOP {
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p2 := obj.Appendp(p, newprog)
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p2.Pc = p.Pc
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p = p2
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}
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p.As = as
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switch len(args) {
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case 0:
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p.From = obj.Addr{}
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p.To = obj.Addr{}
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case 1:
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if unaryDst[as] {
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p.From = obj.Addr{}
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p.To = args[0]
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} else {
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p.From = args[0]
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p.To = obj.Addr{}
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}
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case 2:
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p.From = args[0]
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p.To = args[1]
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default:
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panic("bad args")
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}
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return p
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}
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framesize := s.Func.Text.To.Offset
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if framesize < 0 {
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panic("bad framesize")
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}
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s.Func.Args = s.Func.Text.To.Val.(int32)
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s.Func.Locals = int32(framesize)
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if s.Func.Text.From.Sym.Wrapper() {
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// if g._panic != nil && g._panic.argp == FP {
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// g._panic.argp = bottom-of-frame
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// }
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//
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// MOVD g_panic(g), R0
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// Get R0
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// I64Eqz
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// Not
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// If
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// Get SP
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// I64ExtendI32U
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// I64Const $framesize+8
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// I64Add
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// I64Load panic_argp(R0)
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// I64Eq
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// If
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// MOVD SP, panic_argp(R0)
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// End
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// End
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gpanic := obj.Addr{
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Type: obj.TYPE_MEM,
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Reg: REGG,
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Offset: 4 * 8, // g_panic
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}
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panicargp := obj.Addr{
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Type: obj.TYPE_MEM,
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Reg: REG_R0,
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Offset: 0, // panic.argp
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}
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p := s.Func.Text
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p = appendp(p, AMOVD, gpanic, regAddr(REG_R0))
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p = appendp(p, AGet, regAddr(REG_R0))
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p = appendp(p, AI64Eqz)
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p = appendp(p, ANot)
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p = appendp(p, AIf)
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p = appendp(p, AGet, regAddr(REG_SP))
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p = appendp(p, AI64ExtendI32U)
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p = appendp(p, AI64Const, constAddr(framesize+8))
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p = appendp(p, AI64Add)
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p = appendp(p, AI64Load, panicargp)
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p = appendp(p, AI64Eq)
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p = appendp(p, AIf)
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p = appendp(p, AMOVD, regAddr(REG_SP), panicargp)
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p = appendp(p, AEnd)
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p = appendp(p, AEnd)
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}
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if framesize > 0 {
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p := s.Func.Text
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p = appendp(p, AGet, regAddr(REG_SP))
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p = appendp(p, AI32Const, constAddr(framesize))
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p = appendp(p, AI32Sub)
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p = appendp(p, ASet, regAddr(REG_SP))
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p.Spadj = int32(framesize)
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}
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// Introduce resume points for CALL instructions
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// and collect other explicit resume points.
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numResumePoints := 0
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explicitBlockDepth := 0
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pc := int64(0) // pc is only incremented when necessary, this avoids bloat of the BrTable instruction
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var tableIdxs []uint64
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tablePC := int64(0)
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base := ctxt.PosTable.Pos(s.Func.Text.Pos).Base()
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for p := s.Func.Text; p != nil; p = p.Link {
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prevBase := base
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base = ctxt.PosTable.Pos(p.Pos).Base()
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switch p.As {
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case ABlock, ALoop, AIf:
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explicitBlockDepth++
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case AEnd:
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if explicitBlockDepth == 0 {
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panic("End without block")
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}
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explicitBlockDepth--
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case ARESUMEPOINT:
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if explicitBlockDepth != 0 {
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panic("RESUME can only be used on toplevel")
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}
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p.As = AEnd
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for tablePC <= pc {
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tableIdxs = append(tableIdxs, uint64(numResumePoints))
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tablePC++
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}
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numResumePoints++
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pc++
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case obj.ACALL:
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if explicitBlockDepth != 0 {
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panic("CALL can only be used on toplevel, try CALLNORESUME instead")
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}
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appendp(p, ARESUMEPOINT)
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}
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p.Pc = pc
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// Increase pc whenever some pc-value table needs a new entry. Don't increase it
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// more often to avoid bloat of the BrTable instruction.
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// The "base != prevBase" condition detects inlined instructions. They are an
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// implicit call, so entering and leaving this section affects the stack trace.
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if p.As == ACALLNORESUME || p.As == obj.ANOP || p.As == ANop || p.Spadj != 0 || base != prevBase {
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pc++
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if p.To.Sym == sigpanic {
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// The panic stack trace expects the PC at the call of sigpanic,
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// not the next one. However, runtime.Caller subtracts 1 from the
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// PC. To make both PC and PC-1 work (have the same line number),
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// we advance the PC by 2 at sigpanic.
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pc++
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}
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}
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}
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tableIdxs = append(tableIdxs, uint64(numResumePoints))
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s.Size = pc + 1
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if !s.Func.Text.From.Sym.NoSplit() {
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p := s.Func.Text
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if framesize <= objabi.StackSmall {
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// small stack: SP <= stackguard
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// Get SP
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// Get g
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// I32WrapI64
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// I32Load $stackguard0
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// I32GtU
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p = appendp(p, AGet, regAddr(REG_SP))
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p = appendp(p, AGet, regAddr(REGG))
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p = appendp(p, AI32WrapI64)
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p = appendp(p, AI32Load, constAddr(2*int64(ctxt.Arch.PtrSize))) // G.stackguard0
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p = appendp(p, AI32LeU)
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} else {
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// large stack: SP-framesize <= stackguard-StackSmall
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// SP <= stackguard+(framesize-StackSmall)
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// Get SP
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// Get g
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// I32WrapI64
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// I32Load $stackguard0
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// I32Const $(framesize-StackSmall)
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// I32Add
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// I32GtU
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p = appendp(p, AGet, regAddr(REG_SP))
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p = appendp(p, AGet, regAddr(REGG))
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p = appendp(p, AI32WrapI64)
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p = appendp(p, AI32Load, constAddr(2*int64(ctxt.Arch.PtrSize))) // G.stackguard0
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p = appendp(p, AI32Const, constAddr(int64(framesize)-objabi.StackSmall))
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p = appendp(p, AI32Add)
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p = appendp(p, AI32LeU)
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}
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// TODO(neelance): handle wraparound case
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p = appendp(p, AIf)
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p = appendp(p, obj.ACALL, constAddr(0))
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if s.Func.Text.From.Sym.NeedCtxt() {
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p.To = obj.Addr{Type: obj.TYPE_MEM, Name: obj.NAME_EXTERN, Sym: morestack}
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} else {
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p.To = obj.Addr{Type: obj.TYPE_MEM, Name: obj.NAME_EXTERN, Sym: morestackNoCtxt}
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}
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p = appendp(p, AEnd)
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}
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// record the branches targeting the entry loop and the unwind exit,
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// their targets with be filled in later
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var entryPointLoopBranches []*obj.Prog
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var unwindExitBranches []*obj.Prog
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currentDepth := 0
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for p := s.Func.Text; p != nil; p = p.Link {
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switch p.As {
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case ABlock, ALoop, AIf:
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currentDepth++
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case AEnd:
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currentDepth--
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}
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switch p.As {
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case obj.AJMP:
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jmp := *p
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p.As = obj.ANOP
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if jmp.To.Type == obj.TYPE_BRANCH {
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// jump to basic block
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p = appendp(p, AI32Const, constAddr(jmp.To.Val.(*obj.Prog).Pc))
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p = appendp(p, ASet, regAddr(REG_PC_B)) // write next basic block to PC_B
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p = appendp(p, ABr) // jump to beginning of entryPointLoop
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entryPointLoopBranches = append(entryPointLoopBranches, p)
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break
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}
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// low-level WebAssembly call to function
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switch jmp.To.Type {
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case obj.TYPE_MEM:
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if !notUsePC_B[jmp.To.Sym.Name] {
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// Set PC_B parameter to function entry.
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p = appendp(p, AI32Const, constAddr(0))
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}
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p = appendp(p, ACall, jmp.To)
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case obj.TYPE_NONE:
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// (target PC is on stack)
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p = appendp(p, AI32WrapI64)
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p = appendp(p, AI32Const, constAddr(16)) // only needs PC_F bits (16-31), PC_B bits (0-15) are zero
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p = appendp(p, AI32ShrU)
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// Set PC_B parameter to function entry.
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// We need to push this before pushing the target PC_F,
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// so temporarily pop PC_F, using our REG_PC_B as a
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// scratch register, and push it back after pushing 0.
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p = appendp(p, ASet, regAddr(REG_PC_B))
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p = appendp(p, AI32Const, constAddr(0))
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p = appendp(p, AGet, regAddr(REG_PC_B))
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p = appendp(p, ACallIndirect)
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default:
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panic("bad target for JMP")
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}
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p = appendp(p, AReturn)
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case obj.ACALL, ACALLNORESUME:
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call := *p
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p.As = obj.ANOP
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pcAfterCall := call.Link.Pc
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if call.To.Sym == sigpanic {
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pcAfterCall-- // sigpanic expects to be called without advancing the pc
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}
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// jmpdefer manipulates the return address on the stack so deferreturn gets called repeatedly.
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// Model this in WebAssembly with a loop.
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if call.To.Sym == deferreturn {
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p = appendp(p, ALoop)
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}
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// SP -= 8
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p = appendp(p, AGet, regAddr(REG_SP))
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p = appendp(p, AI32Const, constAddr(8))
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p = appendp(p, AI32Sub)
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p = appendp(p, ASet, regAddr(REG_SP))
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// write return address to Go stack
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p = appendp(p, AGet, regAddr(REG_SP))
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p = appendp(p, AI64Const, obj.Addr{
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Type: obj.TYPE_ADDR,
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Name: obj.NAME_EXTERN,
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Sym: s, // PC_F
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Offset: pcAfterCall, // PC_B
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})
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p = appendp(p, AI64Store, constAddr(0))
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// low-level WebAssembly call to function
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switch call.To.Type {
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case obj.TYPE_MEM:
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if !notUsePC_B[call.To.Sym.Name] {
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// Set PC_B parameter to function entry.
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p = appendp(p, AI32Const, constAddr(0))
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}
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p = appendp(p, ACall, call.To)
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case obj.TYPE_NONE:
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// (target PC is on stack)
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p = appendp(p, AI32WrapI64)
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p = appendp(p, AI32Const, constAddr(16)) // only needs PC_F bits (16-31), PC_B bits (0-15) are zero
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p = appendp(p, AI32ShrU)
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// Set PC_B parameter to function entry.
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// We need to push this before pushing the target PC_F,
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// so temporarily pop PC_F, using our PC_B as a
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// scratch register, and push it back after pushing 0.
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p = appendp(p, ASet, regAddr(REG_PC_B))
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p = appendp(p, AI32Const, constAddr(0))
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p = appendp(p, AGet, regAddr(REG_PC_B))
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p = appendp(p, ACallIndirect)
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default:
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panic("bad target for CALL")
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}
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// gcWriteBarrier has no return value, it never unwinds the stack
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if call.To.Sym == gcWriteBarrier {
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break
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}
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// jmpdefer removes the frame of deferreturn from the Go stack.
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// However, its WebAssembly function still returns normally,
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// so we need to return from deferreturn without removing its
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// stack frame (no RET), because the frame is already gone.
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if call.To.Sym == jmpdefer {
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p = appendp(p, AReturn)
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break
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}
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// return value of call is on the top of the stack, indicating whether to unwind the WebAssembly stack
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if call.As == ACALLNORESUME && call.To.Sym != sigpanic && call.To.Sym != sigpanic0 { // sigpanic unwinds the stack, but it never resumes
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// trying to unwind WebAssembly stack but call has no resume point, terminate with error
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p = appendp(p, AIf)
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p = appendp(p, obj.AUNDEF)
|
|
p = appendp(p, AEnd)
|
|
} else {
|
|
// unwinding WebAssembly stack to switch goroutine, return 1
|
|
p = appendp(p, ABrIf)
|
|
unwindExitBranches = append(unwindExitBranches, p)
|
|
}
|
|
|
|
// jump to before the call if jmpdefer has reset the return address to the call's PC
|
|
if call.To.Sym == deferreturn {
|
|
// get PC_B from -8(SP)
|
|
p = appendp(p, AGet, regAddr(REG_SP))
|
|
p = appendp(p, AI32Const, constAddr(8))
|
|
p = appendp(p, AI32Sub)
|
|
p = appendp(p, AI32Load16U, constAddr(0))
|
|
p = appendp(p, ATee, regAddr(REG_PC_B))
|
|
|
|
p = appendp(p, AI32Const, constAddr(call.Pc))
|
|
p = appendp(p, AI32Eq)
|
|
p = appendp(p, ABrIf, constAddr(0))
|
|
p = appendp(p, AEnd) // end of Loop
|
|
}
|
|
|
|
case obj.ARET, ARETUNWIND:
|
|
ret := *p
|
|
p.As = obj.ANOP
|
|
|
|
if framesize > 0 {
|
|
// SP += framesize
|
|
p = appendp(p, AGet, regAddr(REG_SP))
|
|
p = appendp(p, AI32Const, constAddr(framesize))
|
|
p = appendp(p, AI32Add)
|
|
p = appendp(p, ASet, regAddr(REG_SP))
|
|
// TODO(neelance): This should theoretically set Spadj, but it only works without.
|
|
// p.Spadj = int32(-framesize)
|
|
}
|
|
|
|
if ret.To.Type == obj.TYPE_MEM {
|
|
// Set PC_B parameter to function entry.
|
|
p = appendp(p, AI32Const, constAddr(0))
|
|
|
|
// low-level WebAssembly call to function
|
|
p = appendp(p, ACall, ret.To)
|
|
p = appendp(p, AReturn)
|
|
break
|
|
}
|
|
|
|
// SP += 8
|
|
p = appendp(p, AGet, regAddr(REG_SP))
|
|
p = appendp(p, AI32Const, constAddr(8))
|
|
p = appendp(p, AI32Add)
|
|
p = appendp(p, ASet, regAddr(REG_SP))
|
|
|
|
if ret.As == ARETUNWIND {
|
|
// function needs to unwind the WebAssembly stack, return 1
|
|
p = appendp(p, AI32Const, constAddr(1))
|
|
p = appendp(p, AReturn)
|
|
break
|
|
}
|
|
|
|
// not unwinding the WebAssembly stack, return 0
|
|
p = appendp(p, AI32Const, constAddr(0))
|
|
p = appendp(p, AReturn)
|
|
}
|
|
}
|
|
|
|
for p := s.Func.Text; p != nil; p = p.Link {
|
|
switch p.From.Name {
|
|
case obj.NAME_AUTO:
|
|
p.From.Offset += int64(framesize)
|
|
case obj.NAME_PARAM:
|
|
p.From.Reg = REG_SP
|
|
p.From.Offset += int64(framesize) + 8 // parameters are after the frame and the 8-byte return address
|
|
}
|
|
|
|
switch p.To.Name {
|
|
case obj.NAME_AUTO:
|
|
p.To.Offset += int64(framesize)
|
|
case obj.NAME_PARAM:
|
|
p.To.Reg = REG_SP
|
|
p.To.Offset += int64(framesize) + 8 // parameters are after the frame and the 8-byte return address
|
|
}
|
|
|
|
switch p.As {
|
|
case AGet:
|
|
if p.From.Type == obj.TYPE_ADDR {
|
|
get := *p
|
|
p.As = obj.ANOP
|
|
|
|
switch get.From.Name {
|
|
case obj.NAME_EXTERN:
|
|
p = appendp(p, AI64Const, get.From)
|
|
case obj.NAME_AUTO, obj.NAME_PARAM:
|
|
p = appendp(p, AGet, regAddr(get.From.Reg))
|
|
if get.From.Reg == REG_SP {
|
|
p = appendp(p, AI64ExtendI32U)
|
|
}
|
|
if get.From.Offset != 0 {
|
|
p = appendp(p, AI64Const, constAddr(get.From.Offset))
|
|
p = appendp(p, AI64Add)
|
|
}
|
|
default:
|
|
panic("bad Get: invalid name")
|
|
}
|
|
}
|
|
|
|
case AI32Load, AI64Load, AF32Load, AF64Load, AI32Load8S, AI32Load8U, AI32Load16S, AI32Load16U, AI64Load8S, AI64Load8U, AI64Load16S, AI64Load16U, AI64Load32S, AI64Load32U:
|
|
if p.From.Type == obj.TYPE_MEM {
|
|
as := p.As
|
|
from := p.From
|
|
|
|
p.As = AGet
|
|
p.From = regAddr(from.Reg)
|
|
|
|
if from.Reg != REG_SP {
|
|
p = appendp(p, AI32WrapI64)
|
|
}
|
|
|
|
p = appendp(p, as, constAddr(from.Offset))
|
|
}
|
|
|
|
case AMOVB, AMOVH, AMOVW, AMOVD:
|
|
mov := *p
|
|
p.As = obj.ANOP
|
|
|
|
var loadAs obj.As
|
|
var storeAs obj.As
|
|
switch mov.As {
|
|
case AMOVB:
|
|
loadAs = AI64Load8U
|
|
storeAs = AI64Store8
|
|
case AMOVH:
|
|
loadAs = AI64Load16U
|
|
storeAs = AI64Store16
|
|
case AMOVW:
|
|
loadAs = AI64Load32U
|
|
storeAs = AI64Store32
|
|
case AMOVD:
|
|
loadAs = AI64Load
|
|
storeAs = AI64Store
|
|
}
|
|
|
|
appendValue := func() {
|
|
switch mov.From.Type {
|
|
case obj.TYPE_CONST:
|
|
p = appendp(p, AI64Const, constAddr(mov.From.Offset))
|
|
|
|
case obj.TYPE_ADDR:
|
|
switch mov.From.Name {
|
|
case obj.NAME_NONE, obj.NAME_PARAM, obj.NAME_AUTO:
|
|
p = appendp(p, AGet, regAddr(mov.From.Reg))
|
|
if mov.From.Reg == REG_SP {
|
|
p = appendp(p, AI64ExtendI32U)
|
|
}
|
|
p = appendp(p, AI64Const, constAddr(mov.From.Offset))
|
|
p = appendp(p, AI64Add)
|
|
case obj.NAME_EXTERN:
|
|
p = appendp(p, AI64Const, mov.From)
|
|
default:
|
|
panic("bad name for MOV")
|
|
}
|
|
|
|
case obj.TYPE_REG:
|
|
p = appendp(p, AGet, mov.From)
|
|
if mov.From.Reg == REG_SP {
|
|
p = appendp(p, AI64ExtendI32U)
|
|
}
|
|
|
|
case obj.TYPE_MEM:
|
|
p = appendp(p, AGet, regAddr(mov.From.Reg))
|
|
if mov.From.Reg != REG_SP {
|
|
p = appendp(p, AI32WrapI64)
|
|
}
|
|
p = appendp(p, loadAs, constAddr(mov.From.Offset))
|
|
|
|
default:
|
|
panic("bad MOV type")
|
|
}
|
|
}
|
|
|
|
switch mov.To.Type {
|
|
case obj.TYPE_REG:
|
|
appendValue()
|
|
if mov.To.Reg == REG_SP {
|
|
p = appendp(p, AI32WrapI64)
|
|
}
|
|
p = appendp(p, ASet, mov.To)
|
|
|
|
case obj.TYPE_MEM:
|
|
switch mov.To.Name {
|
|
case obj.NAME_NONE, obj.NAME_PARAM:
|
|
p = appendp(p, AGet, regAddr(mov.To.Reg))
|
|
if mov.To.Reg != REG_SP {
|
|
p = appendp(p, AI32WrapI64)
|
|
}
|
|
case obj.NAME_EXTERN:
|
|
p = appendp(p, AI32Const, obj.Addr{Type: obj.TYPE_ADDR, Name: obj.NAME_EXTERN, Sym: mov.To.Sym})
|
|
default:
|
|
panic("bad MOV name")
|
|
}
|
|
appendValue()
|
|
p = appendp(p, storeAs, constAddr(mov.To.Offset))
|
|
|
|
default:
|
|
panic("bad MOV type")
|
|
}
|
|
|
|
case ACallImport:
|
|
p.As = obj.ANOP
|
|
p = appendp(p, AGet, regAddr(REG_SP))
|
|
p = appendp(p, ACall, obj.Addr{Type: obj.TYPE_MEM, Name: obj.NAME_EXTERN, Sym: s})
|
|
p.Mark = WasmImport
|
|
}
|
|
}
|
|
|
|
{
|
|
p := s.Func.Text
|
|
if len(unwindExitBranches) > 0 {
|
|
p = appendp(p, ABlock) // unwindExit, used to return 1 when unwinding the stack
|
|
for _, b := range unwindExitBranches {
|
|
b.To = obj.Addr{Type: obj.TYPE_BRANCH, Val: p}
|
|
}
|
|
}
|
|
if len(entryPointLoopBranches) > 0 {
|
|
p = appendp(p, ALoop) // entryPointLoop, used to jump between basic blocks
|
|
for _, b := range entryPointLoopBranches {
|
|
b.To = obj.Addr{Type: obj.TYPE_BRANCH, Val: p}
|
|
}
|
|
}
|
|
if numResumePoints > 0 {
|
|
// Add Block instructions for resume points and BrTable to jump to selected resume point.
|
|
for i := 0; i < numResumePoints+1; i++ {
|
|
p = appendp(p, ABlock)
|
|
}
|
|
p = appendp(p, AGet, regAddr(REG_PC_B)) // read next basic block from PC_B
|
|
p = appendp(p, ABrTable, obj.Addr{Val: tableIdxs})
|
|
p = appendp(p, AEnd) // end of Block
|
|
}
|
|
for p.Link != nil {
|
|
p = p.Link // function instructions
|
|
}
|
|
if len(entryPointLoopBranches) > 0 {
|
|
p = appendp(p, AEnd) // end of entryPointLoop
|
|
}
|
|
p = appendp(p, obj.AUNDEF)
|
|
if len(unwindExitBranches) > 0 {
|
|
p = appendp(p, AEnd) // end of unwindExit
|
|
p = appendp(p, AI32Const, constAddr(1))
|
|
}
|
|
}
|
|
|
|
currentDepth = 0
|
|
blockDepths := make(map[*obj.Prog]int)
|
|
for p := s.Func.Text; p != nil; p = p.Link {
|
|
switch p.As {
|
|
case ABlock, ALoop, AIf:
|
|
currentDepth++
|
|
blockDepths[p] = currentDepth
|
|
case AEnd:
|
|
currentDepth--
|
|
}
|
|
|
|
switch p.As {
|
|
case ABr, ABrIf:
|
|
if p.To.Type == obj.TYPE_BRANCH {
|
|
blockDepth, ok := blockDepths[p.To.Val.(*obj.Prog)]
|
|
if !ok {
|
|
panic("label not at block")
|
|
}
|
|
p.To = constAddr(int64(currentDepth - blockDepth))
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
func constAddr(value int64) obj.Addr {
|
|
return obj.Addr{Type: obj.TYPE_CONST, Offset: value}
|
|
}
|
|
|
|
func regAddr(reg int16) obj.Addr {
|
|
return obj.Addr{Type: obj.TYPE_REG, Reg: reg}
|
|
}
|
|
|
|
// Most of the Go functions has a single parameter (PC_B) in
|
|
// Wasm ABI. This is a list of exceptions.
|
|
var notUsePC_B = map[string]bool{
|
|
"_rt0_wasm_js": true,
|
|
"wasm_export_run": true,
|
|
"wasm_export_resume": true,
|
|
"wasm_export_getsp": true,
|
|
"wasm_pc_f_loop": true,
|
|
"runtime.wasmMove": true,
|
|
"runtime.wasmZero": true,
|
|
"runtime.wasmDiv": true,
|
|
"runtime.wasmTruncS": true,
|
|
"runtime.wasmTruncU": true,
|
|
"runtime.gcWriteBarrier": true,
|
|
"cmpbody": true,
|
|
"memeqbody": true,
|
|
"memcmp": true,
|
|
"memchr": true,
|
|
}
|
|
|
|
func assemble(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) {
|
|
type regVar struct {
|
|
global bool
|
|
index uint64
|
|
}
|
|
|
|
type varDecl struct {
|
|
count uint64
|
|
typ valueType
|
|
}
|
|
|
|
hasLocalSP := false
|
|
regVars := [MAXREG - MINREG]*regVar{
|
|
REG_SP - MINREG: {true, 0},
|
|
REG_CTXT - MINREG: {true, 1},
|
|
REG_g - MINREG: {true, 2},
|
|
REG_RET0 - MINREG: {true, 3},
|
|
REG_RET1 - MINREG: {true, 4},
|
|
REG_RET2 - MINREG: {true, 5},
|
|
REG_RET3 - MINREG: {true, 6},
|
|
REG_PAUSE - MINREG: {true, 7},
|
|
}
|
|
var varDecls []*varDecl
|
|
useAssemblyRegMap := func() {
|
|
for i := int16(0); i < 16; i++ {
|
|
regVars[REG_R0+i-MINREG] = ®Var{false, uint64(i)}
|
|
}
|
|
}
|
|
|
|
// Function starts with declaration of locals: numbers and types.
|
|
// Some functions use a special calling convention.
|
|
switch s.Name {
|
|
case "_rt0_wasm_js", "wasm_export_run", "wasm_export_resume", "wasm_export_getsp", "wasm_pc_f_loop",
|
|
"runtime.wasmMove", "runtime.wasmZero", "runtime.wasmDiv", "runtime.wasmTruncS", "runtime.wasmTruncU", "memeqbody":
|
|
varDecls = []*varDecl{}
|
|
useAssemblyRegMap()
|
|
case "memchr", "memcmp":
|
|
varDecls = []*varDecl{{count: 2, typ: i32}}
|
|
useAssemblyRegMap()
|
|
case "cmpbody":
|
|
varDecls = []*varDecl{{count: 2, typ: i64}}
|
|
useAssemblyRegMap()
|
|
case "runtime.gcWriteBarrier":
|
|
varDecls = []*varDecl{{count: 4, typ: i64}}
|
|
useAssemblyRegMap()
|
|
default:
|
|
// Normal calling convention: PC_B as WebAssembly parameter. First local variable is local SP cache.
|
|
regVars[REG_PC_B-MINREG] = ®Var{false, 0}
|
|
hasLocalSP = true
|
|
|
|
var regUsed [MAXREG - MINREG]bool
|
|
for p := s.Func.Text; p != nil; p = p.Link {
|
|
if p.From.Reg != 0 {
|
|
regUsed[p.From.Reg-MINREG] = true
|
|
}
|
|
if p.To.Reg != 0 {
|
|
regUsed[p.To.Reg-MINREG] = true
|
|
}
|
|
}
|
|
|
|
regs := []int16{REG_SP}
|
|
for reg := int16(REG_R0); reg <= REG_F31; reg++ {
|
|
if regUsed[reg-MINREG] {
|
|
regs = append(regs, reg)
|
|
}
|
|
}
|
|
|
|
var lastDecl *varDecl
|
|
for i, reg := range regs {
|
|
t := regType(reg)
|
|
if lastDecl == nil || lastDecl.typ != t {
|
|
lastDecl = &varDecl{
|
|
count: 0,
|
|
typ: t,
|
|
}
|
|
varDecls = append(varDecls, lastDecl)
|
|
}
|
|
lastDecl.count++
|
|
if reg != REG_SP {
|
|
regVars[reg-MINREG] = ®Var{false, 1 + uint64(i)}
|
|
}
|
|
}
|
|
}
|
|
|
|
w := new(bytes.Buffer)
|
|
|
|
writeUleb128(w, uint64(len(varDecls)))
|
|
for _, decl := range varDecls {
|
|
writeUleb128(w, decl.count)
|
|
w.WriteByte(byte(decl.typ))
|
|
}
|
|
|
|
if hasLocalSP {
|
|
// Copy SP from its global variable into a local variable. Accessing a local variable is more efficient.
|
|
updateLocalSP(w)
|
|
}
|
|
|
|
for p := s.Func.Text; p != nil; p = p.Link {
|
|
switch p.As {
|
|
case AGet:
|
|
if p.From.Type != obj.TYPE_REG {
|
|
panic("bad Get: argument is not a register")
|
|
}
|
|
reg := p.From.Reg
|
|
v := regVars[reg-MINREG]
|
|
if v == nil {
|
|
panic("bad Get: invalid register")
|
|
}
|
|
if reg == REG_SP && hasLocalSP {
|
|
writeOpcode(w, ALocalGet)
|
|
writeUleb128(w, 1) // local SP
|
|
continue
|
|
}
|
|
if v.global {
|
|
writeOpcode(w, AGlobalGet)
|
|
} else {
|
|
writeOpcode(w, ALocalGet)
|
|
}
|
|
writeUleb128(w, v.index)
|
|
continue
|
|
|
|
case ASet:
|
|
if p.To.Type != obj.TYPE_REG {
|
|
panic("bad Set: argument is not a register")
|
|
}
|
|
reg := p.To.Reg
|
|
v := regVars[reg-MINREG]
|
|
if v == nil {
|
|
panic("bad Set: invalid register")
|
|
}
|
|
if reg == REG_SP && hasLocalSP {
|
|
writeOpcode(w, ALocalTee)
|
|
writeUleb128(w, 1) // local SP
|
|
}
|
|
if v.global {
|
|
writeOpcode(w, AGlobalSet)
|
|
} else {
|
|
if p.Link.As == AGet && p.Link.From.Reg == reg {
|
|
writeOpcode(w, ALocalTee)
|
|
p = p.Link
|
|
} else {
|
|
writeOpcode(w, ALocalSet)
|
|
}
|
|
}
|
|
writeUleb128(w, v.index)
|
|
continue
|
|
|
|
case ATee:
|
|
if p.To.Type != obj.TYPE_REG {
|
|
panic("bad Tee: argument is not a register")
|
|
}
|
|
reg := p.To.Reg
|
|
v := regVars[reg-MINREG]
|
|
if v == nil {
|
|
panic("bad Tee: invalid register")
|
|
}
|
|
writeOpcode(w, ALocalTee)
|
|
writeUleb128(w, v.index)
|
|
continue
|
|
|
|
case ANot:
|
|
writeOpcode(w, AI32Eqz)
|
|
continue
|
|
|
|
case obj.AUNDEF:
|
|
writeOpcode(w, AUnreachable)
|
|
continue
|
|
|
|
case obj.ANOP, obj.ATEXT, obj.AFUNCDATA, obj.APCDATA:
|
|
// ignore
|
|
continue
|
|
}
|
|
|
|
writeOpcode(w, p.As)
|
|
|
|
switch p.As {
|
|
case ABlock, ALoop, AIf:
|
|
if p.From.Offset != 0 {
|
|
// block type, rarely used, e.g. for code compiled with emscripten
|
|
w.WriteByte(0x80 - byte(p.From.Offset))
|
|
continue
|
|
}
|
|
w.WriteByte(0x40)
|
|
|
|
case ABr, ABrIf:
|
|
if p.To.Type != obj.TYPE_CONST {
|
|
panic("bad Br/BrIf")
|
|
}
|
|
writeUleb128(w, uint64(p.To.Offset))
|
|
|
|
case ABrTable:
|
|
idxs := p.To.Val.([]uint64)
|
|
writeUleb128(w, uint64(len(idxs)-1))
|
|
for _, idx := range idxs {
|
|
writeUleb128(w, idx)
|
|
}
|
|
|
|
case ACall:
|
|
switch p.To.Type {
|
|
case obj.TYPE_CONST:
|
|
writeUleb128(w, uint64(p.To.Offset))
|
|
|
|
case obj.TYPE_MEM:
|
|
if p.To.Name != obj.NAME_EXTERN && p.To.Name != obj.NAME_STATIC {
|
|
fmt.Println(p.To)
|
|
panic("bad name for Call")
|
|
}
|
|
r := obj.Addrel(s)
|
|
r.Off = int32(w.Len())
|
|
r.Type = objabi.R_CALL
|
|
if p.Mark&WasmImport != 0 {
|
|
r.Type = objabi.R_WASMIMPORT
|
|
}
|
|
r.Sym = p.To.Sym
|
|
if hasLocalSP {
|
|
// The stack may have moved, which changes SP. Update the local SP variable.
|
|
updateLocalSP(w)
|
|
}
|
|
|
|
default:
|
|
panic("bad type for Call")
|
|
}
|
|
|
|
case ACallIndirect:
|
|
writeUleb128(w, uint64(p.To.Offset))
|
|
w.WriteByte(0x00) // reserved value
|
|
if hasLocalSP {
|
|
// The stack may have moved, which changes SP. Update the local SP variable.
|
|
updateLocalSP(w)
|
|
}
|
|
|
|
case AI32Const, AI64Const:
|
|
if p.From.Name == obj.NAME_EXTERN {
|
|
r := obj.Addrel(s)
|
|
r.Off = int32(w.Len())
|
|
r.Type = objabi.R_ADDR
|
|
r.Sym = p.From.Sym
|
|
r.Add = p.From.Offset
|
|
break
|
|
}
|
|
writeSleb128(w, p.From.Offset)
|
|
|
|
case AF32Const:
|
|
b := make([]byte, 4)
|
|
binary.LittleEndian.PutUint32(b, math.Float32bits(float32(p.From.Val.(float64))))
|
|
w.Write(b)
|
|
|
|
case AF64Const:
|
|
b := make([]byte, 8)
|
|
binary.LittleEndian.PutUint64(b, math.Float64bits(p.From.Val.(float64)))
|
|
w.Write(b)
|
|
|
|
case AI32Load, AI64Load, AF32Load, AF64Load, AI32Load8S, AI32Load8U, AI32Load16S, AI32Load16U, AI64Load8S, AI64Load8U, AI64Load16S, AI64Load16U, AI64Load32S, AI64Load32U:
|
|
if p.From.Offset < 0 {
|
|
panic("negative offset for *Load")
|
|
}
|
|
if p.From.Type != obj.TYPE_CONST {
|
|
panic("bad type for *Load")
|
|
}
|
|
if p.From.Offset > math.MaxUint32 {
|
|
ctxt.Diag("bad offset in %v", p)
|
|
}
|
|
writeUleb128(w, align(p.As))
|
|
writeUleb128(w, uint64(p.From.Offset))
|
|
|
|
case AI32Store, AI64Store, AF32Store, AF64Store, AI32Store8, AI32Store16, AI64Store8, AI64Store16, AI64Store32:
|
|
if p.To.Offset < 0 {
|
|
panic("negative offset")
|
|
}
|
|
if p.From.Offset > math.MaxUint32 {
|
|
ctxt.Diag("bad offset in %v", p)
|
|
}
|
|
writeUleb128(w, align(p.As))
|
|
writeUleb128(w, uint64(p.To.Offset))
|
|
|
|
case ACurrentMemory, AGrowMemory:
|
|
w.WriteByte(0x00)
|
|
|
|
}
|
|
}
|
|
|
|
w.WriteByte(0x0b) // end
|
|
|
|
s.P = w.Bytes()
|
|
}
|
|
|
|
func updateLocalSP(w *bytes.Buffer) {
|
|
writeOpcode(w, AGlobalGet)
|
|
writeUleb128(w, 0) // global SP
|
|
writeOpcode(w, ALocalSet)
|
|
writeUleb128(w, 1) // local SP
|
|
}
|
|
|
|
func writeOpcode(w *bytes.Buffer, as obj.As) {
|
|
switch {
|
|
case as < AUnreachable:
|
|
panic(fmt.Sprintf("unexpected assembler op: %s", as))
|
|
case as < AEnd:
|
|
w.WriteByte(byte(as - AUnreachable + 0x00))
|
|
case as < ADrop:
|
|
w.WriteByte(byte(as - AEnd + 0x0B))
|
|
case as < ALocalGet:
|
|
w.WriteByte(byte(as - ADrop + 0x1A))
|
|
case as < AI32Load:
|
|
w.WriteByte(byte(as - ALocalGet + 0x20))
|
|
case as < AI32TruncSatF32S:
|
|
w.WriteByte(byte(as - AI32Load + 0x28))
|
|
case as < ALast:
|
|
w.WriteByte(0xFC)
|
|
w.WriteByte(byte(as - AI32TruncSatF32S + 0x00))
|
|
default:
|
|
panic(fmt.Sprintf("unexpected assembler op: %s", as))
|
|
}
|
|
}
|
|
|
|
type valueType byte
|
|
|
|
const (
|
|
i32 valueType = 0x7F
|
|
i64 valueType = 0x7E
|
|
f32 valueType = 0x7D
|
|
f64 valueType = 0x7C
|
|
)
|
|
|
|
func regType(reg int16) valueType {
|
|
switch {
|
|
case reg == REG_SP:
|
|
return i32
|
|
case reg >= REG_R0 && reg <= REG_R15:
|
|
return i64
|
|
case reg >= REG_F0 && reg <= REG_F15:
|
|
return f32
|
|
case reg >= REG_F16 && reg <= REG_F31:
|
|
return f64
|
|
default:
|
|
panic("invalid register")
|
|
}
|
|
}
|
|
|
|
func align(as obj.As) uint64 {
|
|
switch as {
|
|
case AI32Load8S, AI32Load8U, AI64Load8S, AI64Load8U, AI32Store8, AI64Store8:
|
|
return 0
|
|
case AI32Load16S, AI32Load16U, AI64Load16S, AI64Load16U, AI32Store16, AI64Store16:
|
|
return 1
|
|
case AI32Load, AF32Load, AI64Load32S, AI64Load32U, AI32Store, AF32Store, AI64Store32:
|
|
return 2
|
|
case AI64Load, AF64Load, AI64Store, AF64Store:
|
|
return 3
|
|
default:
|
|
panic("align: bad op")
|
|
}
|
|
}
|
|
|
|
func writeUleb128(w io.ByteWriter, v uint64) {
|
|
if v < 128 {
|
|
w.WriteByte(uint8(v))
|
|
return
|
|
}
|
|
more := true
|
|
for more {
|
|
c := uint8(v & 0x7f)
|
|
v >>= 7
|
|
more = v != 0
|
|
if more {
|
|
c |= 0x80
|
|
}
|
|
w.WriteByte(c)
|
|
}
|
|
}
|
|
|
|
func writeSleb128(w io.ByteWriter, v int64) {
|
|
more := true
|
|
for more {
|
|
c := uint8(v & 0x7f)
|
|
s := uint8(v & 0x40)
|
|
v >>= 7
|
|
more = !((v == 0 && s == 0) || (v == -1 && s != 0))
|
|
if more {
|
|
c |= 0x80
|
|
}
|
|
w.WriteByte(c)
|
|
}
|
|
}
|