[Bug target/63634] New: Compiler generated R_AARCH64_TLSLE_ADD_TPREL_HI12/LO12 pair overflowed by large TP offset

["shenhan at google dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63634

            Bug ID: 63634
           Summary: Compiler generated R_AARCH64_TLSLE_ADD_TPREL_HI12/LO12
                    pair overflowed by large TP offset
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: shenhan at google dot com
                CC: jingyu at google dot com, shenhan at google dot com
            Target: aarch64

Created attachment 33798
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=33798&action=edit
Test case

(Trunk) Compiler generates by default the following insn and relocation pair to
access a TLS variable via its offset from TP, like below - 

main:
        mrs     x3, tpidr_el0
        mov     w2, 7
        add     x0, x3, #:tprel_hi12:.LANCHOR0
        add     x0, x0, #:tprel_lo12_nc:.LANCHOR0
        add     x1, x0, 1000
.L2:
        strb    w2, [x0], 1
        cmp     x0, x1
        bne     .L2
>>      add     x3, x3, #:tprel_hi12:.LANCHOR1
>>      add     x3, x3, #:tprel_lo12_nc:.LANCHOR1
        ldr     w0, [x3, 1024]
        ret


Insns where indicated by ">>" are generated to add offset to x3, which is the
TP(thread pointer), the actually offset value is filled in by linker at static
link phase. However this means offsets are limited to 24 bits, in other words,
it fails the attach test case. (The bad things is bfd fails silentlyï resulting
a bad binary.)

To fix this, the compiler/assembler at least needs to generate the following to
support 32-bit TP offset.

>>      movk xx, #:R_AARCH64_TLSLE_MOVW_TPREL_G1, lsl 16
>>      movk xx, #:R_AARCH64_TLSLE_MOVW_TPREL_G0
>>      add  x3, xx