func ssaGenBlock(s *gc.SSAGenState, b, next *ssa.Block) {
s.SetLineno(b.Line)
switch b.Kind {
case ssa.BlockCall:
if b.Succs[0].Block() != next {
p := gc.Prog(obj.AJMP)
p.To.Type = obj.TYPE_BRANCH
s.Branches = append(s.Branches, gc.Branch{P: p, B: b.Succs[0].Block()})
}
case ssa.BlockRet:
gc.Prog(obj.ARET)
case ssa.BlockARMLT:
p := gc.Prog(arm.ABLT)
p.To.Type = obj.TYPE_BRANCH
s.Branches = append(s.Branches, gc.Branch{P: p, B: b.Succs[0].Block()})
p = gc.Prog(obj.AJMP)
p.To.Type = obj.TYPE_BRANCH
s.Branches = append(s.Branches, gc.Branch{P: p, B: b.Succs[1].Block()})
}
}
func ssaGenBlock(s *gc.SSAGenState, b, next *ssa.Block) {
s.SetLineno(b.Line)
switch b.Kind {
case ssa.BlockPlain, ssa.BlockCall, ssa.BlockCheck:
if b.Succs[0].Block() != next {
p := gc.Prog(obj.AJMP)
p.To.Type = obj.TYPE_BRANCH
s.Branches = append(s.Branches, gc.Branch{P: p, B: b.Succs[0].Block()})
}
case ssa.BlockDefer:
// defer returns in rax:
// 0 if we should continue executing
// 1 if we should jump to deferreturn call
p := gc.Prog(x86.ATESTL)
p.From.Type = obj.TYPE_REG
p.From.Reg = x86.REG_AX
p.To.Type = obj.TYPE_REG
p.To.Reg = x86.REG_AX
p = gc.Prog(x86.AJNE)
p.To.Type = obj.TYPE_BRANCH
s.Branches = append(s.Branches, gc.Branch{P: p, B: b.Succs[1].Block()})
if b.Succs[0].Block() != next {
p := gc.Prog(obj.AJMP)
p.To.Type = obj.TYPE_BRANCH
s.Branches = append(s.Branches, gc.Branch{P: p, B: b.Succs[0].Block()})
}
case ssa.BlockExit:
gc.Prog(obj.AUNDEF) // tell plive.go that we never reach here
case ssa.BlockRet:
gc.Prog(obj.ARET)
case ssa.BlockRetJmp:
p := gc.Prog(obj.AJMP)
p.To.Type = obj.TYPE_MEM
p.To.Name = obj.NAME_EXTERN
p.To.Sym = gc.Linksym(b.Aux.(*gc.Sym))
case ssa.BlockAMD64EQF:
gc.SSAGenFPJump(s, b, next, &eqfJumps)
case ssa.BlockAMD64NEF:
gc.SSAGenFPJump(s, b, next, &nefJumps)
case ssa.BlockAMD64EQ, ssa.BlockAMD64NE,
ssa.BlockAMD64LT, ssa.BlockAMD64GE,
ssa.BlockAMD64LE, ssa.BlockAMD64GT,
ssa.BlockAMD64ULT, ssa.BlockAMD64UGT,
ssa.BlockAMD64ULE, ssa.BlockAMD64UGE:
jmp := blockJump[b.Kind]
likely := b.Likely
var p *obj.Prog
switch next {
case b.Succs[0].Block():
p = gc.Prog(jmp.invasm)
likely *= -1
p.To.Type = obj.TYPE_BRANCH
s.Branches = append(s.Branches, gc.Branch{P: p, B: b.Succs[1].Block()})
case b.Succs[1].Block():
p = gc.Prog(jmp.asm)
p.To.Type = obj.TYPE_BRANCH
s.Branches = append(s.Branches, gc.Branch{P: p, B: b.Succs[0].Block()})
default:
p = gc.Prog(jmp.asm)
p.To.Type = obj.TYPE_BRANCH
s.Branches = append(s.Branches, gc.Branch{P: p, B: b.Succs[0].Block()})
q := gc.Prog(obj.AJMP)
q.To.Type = obj.TYPE_BRANCH
s.Branches = append(s.Branches, gc.Branch{P: q, B: b.Succs[1].Block()})
}
// liblink reorders the instruction stream as it sees fit.
// Pass along what we know so liblink can make use of it.
// TODO: Once we've fully switched to SSA,
// make liblink leave our output alone.
switch likely {
case ssa.BranchUnlikely:
p.From.Type = obj.TYPE_CONST
p.From.Offset = 0
case ssa.BranchLikely:
p.From.Type = obj.TYPE_CONST
p.From.Offset = 1
}
default:
b.Unimplementedf("branch not implemented: %s. Control: %s", b.LongString(), b.Control.LongString())
}
}