func progedit(ctxt *liblink.Link, p *liblink.Prog) {
var literal string
var s *liblink.LSym
var tlsfallback *liblink.LSym
p.From.Class = 0
p.To.Class = 0
// Rewrite B/BL to symbol as D_BRANCH.
switch p.As {
case AB,
ABL,
ADUFFZERO,
ADUFFCOPY:
if p.To.Type_ == D_OREG && (p.To.Name == D_EXTERN || p.To.Name == D_STATIC) && p.To.Sym != nil {
p.To.Type_ = D_BRANCH
}
break
}
// Replace TLS register fetches on older ARM procesors.
switch p.As {
// Treat MRC 15, 0, <reg>, C13, C0, 3 specially.
case AMRC:
if p.To.Offset&0xffff0fff == 0xee1d0f70 {
// Because the instruction might be rewriten to a BL which returns in R0
// the register must be zero.
if p.To.Offset&0xf000 != 0 {
ctxt.Diag("%L: TLS MRC instruction must write to R0 as it might get translated into a BL instruction", p.Lineno)
}
if ctxt.Goarm < 7 {
// Replace it with BL runtime.read_tls_fallback(SB) for ARM CPUs that lack the tls extension.
if tlsfallback == nil {
tlsfallback = liblink.Linklookup(ctxt, "runtime.read_tls_fallback", 0)
}
// MOVW LR, R11
p.As = AMOVW
p.From.Type_ = D_REG
p.From.Reg = REGLINK
p.To.Type_ = D_REG
p.To.Reg = REGTMP
// BL runtime.read_tls_fallback(SB)
p = liblink.Appendp(ctxt, p)
p.As = ABL
p.To.Type_ = D_BRANCH
p.To.Sym = tlsfallback
p.To.Offset = 0
// MOVW R11, LR
p = liblink.Appendp(ctxt, p)
p.As = AMOVW
p.From.Type_ = D_REG
p.From.Reg = REGTMP
p.To.Type_ = D_REG
p.To.Reg = REGLINK
break
}
}
// Otherwise, MRC/MCR instructions need no further treatment.
p.As = AWORD
break
}
// Rewrite float constants to values stored in memory.
switch p.As {
case AMOVF:
if p.From.Type_ == D_FCONST && chipfloat5(ctxt, p.From.U.Dval) < 0 && (chipzero5(ctxt, p.From.U.Dval) < 0 || p.Scond&C_SCOND != C_SCOND_NONE) {
var i32 uint32
var f32 float32
f32 = float32(p.From.U.Dval)
i32 = math.Float32bits(f32)
literal = fmt.Sprintf("$f32.%08x", i32)
s = liblink.Linklookup(ctxt, literal, 0)
if s.Type_ == 0 {
s.Type_ = liblink.SRODATA
liblink.Adduint32(ctxt, s, i32)
s.Reachable = 0
}
p.From.Type_ = D_OREG
p.From.Sym = s
p.From.Name = D_EXTERN
p.From.Offset = 0
}
case AMOVD:
if p.From.Type_ == D_FCONST && chipfloat5(ctxt, p.From.U.Dval) < 0 && (chipzero5(ctxt, p.From.U.Dval) < 0 || p.Scond&C_SCOND != C_SCOND_NONE) {
var i64 uint64
i64 = math.Float64bits(p.From.U.Dval)
literal = fmt.Sprintf("$f64.%016x", i64)
s = liblink.Linklookup(ctxt, literal, 0)
if s.Type_ == 0 {
s.Type_ = liblink.SRODATA
liblink.Adduint64(ctxt, s, i64)
s.Reachable = 0
}
p.From.Type_ = D_OREG
p.From.Sym = s
p.From.Name = D_EXTERN
p.From.Offset = 0
}
break
}
if ctxt.Flag_shared != 0 {
// Shared libraries use R_ARM_TLS_IE32 instead of
// R_ARM_TLS_LE32, replacing the link time constant TLS offset in
// runtime.tlsg with an address to a GOT entry containing the
// offset. Rewrite $runtime.tlsg(SB) to runtime.tlsg(SB) to
// compensate.
if ctxt.Tlsg == nil {
ctxt.Tlsg = liblink.Linklookup(ctxt, "runtime.tlsg", 0)
}
if p.From.Type_ == D_CONST && p.From.Name == D_EXTERN && p.From.Sym == ctxt.Tlsg {
p.From.Type_ = D_OREG
}
if p.To.Type_ == D_CONST && p.To.Name == D_EXTERN && p.To.Sym == ctxt.Tlsg {
p.To.Type_ = D_OREG
}
}
}
