LoongArch: Add tls transition support.
Transitions between DESC->IE/LE and IE->LE are supported now.
1. For DESC -> LE:
pcalau12i $a0,%desc_pc_hi20(var) => lu12i.w $a0,%le_hi20(var)
addi.d $a0,$a0,%desc_pc_lo12(var) => ori $a0,$a0,%le_lo12(var)
ld.d $a1,$a0,%desc_ld(var) => NOP
jirl $ra,$a1,%desc_call(var) => NOP
add.d $a0,$a0,$tp
2. For DESC -> IE:
pcalau12i $a0,%desc_pc_hi20(var) => pcalau12i $a0,%ie_pc_hi20(var)
addi.d $a0,$a0,%desc_pc_lo12(var) => ld.d $a0,$a0,%ie_pc_lo12(var)
ld.d $a1,$a0,%desc_ld(var) => NOP
jirl $ra,$a1,%desc_call(var) => NOP
add.d $a0,$a0,$tp
3. For IE -> LE:
pcalau12i $a0,%ie_pc_hi20(var) => lu12i.w $a0,%le_hi20(var)
ld.d $a0,$a0,%ie_pc_lo12(var) => ori $a0,$a0,%le_lo12(var)
add.d $a0,$a0,$tp
4. When a tls variable is accessed using both DESC and IE, DESC transitions
to IE and uses the same GOT entry as IE.
3898e04b8e