[Bug target/116693] New: [RISC-V] @tlsdesc generates duplicate assembler labels

[schwab--- via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116693

            Bug ID: 116693
           Summary: [RISC-V] @tlsdesc<mode> generates duplicate assembler
                    labels
           Product: gcc
           Version: 14.2.0
            Status: UNCONFIRMED
          Keywords: assemble-failure
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: sch...@linux-m68k.org
  Target Milestone: ---
            Target: riscv*-*-*

Current mesa fails to build with LTO because it emits duplicate assembler
labels.

src/gallium/targets/dri/libgallium-24.2.2.so.ltrans125.ltrans.s: Assembler
messages:
src/gallium/targets/dri/libgallium-24.2.2.so.ltrans125.ltrans.s:132389: Error:
symbol `.LT178' is already defined
src/gallium/targets/dri/libgallium-24.2.2.so.ltrans125.ltrans.s:135408: Error:
symbol `.LT226' is already defined
src/gallium/targets/dri/libgallium-24.2.2.so.ltrans125.ltrans.s:136590: Error:
symbol `.LT250' is already defined
make: *** [/tmp/ccU08NIk.mk:252:
src/gallium/targets/dri/libgallium-24.2.2.so.ltrans125.ltrans.o] Error 1

.LBB33241:
        .loc 87 51 35
        .LT178: auipc  
a0,%tlsdesc_hi(_ZGVZN4r60010MemoryPool8instanceEvE2me.lto_priv.0)
        ld      t0,%tlsdesc_load_lo(.LT178)(a0)
        addi    a0,a0,%tlsdesc_add_lo(.LT178)
        jalr    t0,t0,%tlsdesc_call(.LT178)

The problem is that the @tlsdesc<mode> insn uses a label number that is only
unique at the time of the generation, but when the insn is duplicated the label
number is not updated.

The pattern should use the %= format instead of maintaining the label number
explicitly.