To support thumb1 execute-only code we need to support four new
relocations (R_ARM_THM_ALU_ABS_G0_NC, R_ARM_THM_ALU_ABS_G1_NC,
R_ARM_THM_ALU_ABS_G2_NC and R_ARM_THM_ALU_ABS_G3_NC).
These relocations allow the static linker to finalize construction
of symbol address.
Typical sequence of code to get address of the symbol foo is then
the following :
movs r3, #:upper8_15:#foo
lsls r3, #8
adds r3, #:upper0_7:#foo
lsls r3, #8
adds r3, #:lower8_15:#foo
lsls r3, #8
adds r3, #:lower0_7:#foo
This will give following sequence of text and relocations after
assembly :
4: 2300 movs r3, #0
4: R_ARM_THM_ALU_ABS_G3_NC foo
6: 021b lsls r3, r3, #8
8: 3300 adds r3, #0
8: R_ARM_THM_ALU_ABS_G2_NC foo
a: 021b lsls r3, r3, #8
c: 3300 adds r3, #0
c: R_ARM_THM_ALU_ABS_G1_NC foo
e: 021b lsls r3, r3, #8
10: 3300 adds r3, #0
10: R_ARM_THM_ALU_ABS_G0_NC foo
