golang lower 代码
文件路径：/src/cmd/compile/internal/ssa/lower.go
/ Copyright 2015 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 ssa
/ convert to machine-dependent ops
func lower(f *Func) {
/ repeat rewrites until we find no more rewrites
applyRewrite(f, f.Config.lowerBlock, f.Config.lowerValue, removeDeadValues)
}
/ checkLower checks for unlowered opcodes and fails if we find one.
func checkLower(f *Func) {
/ Needs to be a separate phase because it must run after both
/ lowering and a subsequent dead code elimination (because lowering
/ rules may leave dead generic ops behind).
for _, b := range f.Blocks {
for _, v := range b.Values {
if !opcodeTable[v.Op].generic {
continue / lowered
}
switch v.Op {
case OpSP, OpSB, OpInitMem, OpArg, OpArgIntReg, OpArgFloatReg, OpPhi, OpVarDef, OpVarKill, OpVarLive, OpKeepAlive, OpSelect0, OpSelect1, OpSelectN, OpConvert, OpInlMark:
continue / ok not to lower
case OpMakeResult:
if b.Controls[0] == v {
continue
}
case OpGetG:
if f.Config.hasGReg {
/ has hardware g register, regalloc takes care of it
continue / ok not to lower
}
}
s := "not lowered: " + v.String() + ", " + v.Op.String() + " " + v.Type.SimpleString()
for _, a := range v.Args {
s += " " + a.Type.SimpleString()
}
f.Fatalf("%s", s)
}
}
}