Weird Bug when setting register in assembly

I was playing with blue pill (Stm32F103CB) and trying to set r7 register via assembly,

.syntax unified
.cpu cortex-m3
.fpu softvfp
.thumb

.global vtable
.global reset_handler

.type vtable, %object
vtable:
    .word _estack
    .word reset_handler
.size vtable, .-vtable


.type reset_handler, %function
reset_handler:

    LDR  r0, =_estack
    MOV  sp, r0
    LDR  r7, =0xDEADBEEF
.size reset_handler, .-reset_handler

The bug is that when i observe the register values via gdb -> info registers i see r8 register set instead of r7 as can be seen in below image.

objdump disassembly of elf also seems correct.

I am unable to understand why this is happening, tried the same with multiple boards, how can i debug and resolve this issue.

Thanks in advance.

Ok so i did some further tests.

The issue is with this opensource stlink gdb server:

https://github.com/stlink-org/stlink

All the registers are numbered as r# + 1 for some reason, and even the sp value is shown as lr.

I tried with openocd instead and everything works as expected.

https://repo.or.cz/w/openocd.git

Will raise a ticket in the stlink-org repo for this.