wamr/arm: Add CFI directives to Thumb VFP assembly for better debugging (#4697)

Add Call Frame Information (CFI) directives to invokeNative_thumb_vfp.s
to improve stack unwinding and debugging capabilities on ARM platforms.
This enables better backtrace generation and crash analysis.

Changes include:
- Add .cfi_startproc/.cfi_endproc directives for proper frame tracking
- Add .cfi_def_cfa_offset and .cfi_def_cfa to track stack pointer changes
- Add .cfi_offset directives to track saved register locations
- Convert local labels to use .L prefix following assembly conventions

These CFI directives allow debuggers and exception handlers to properly
unwind the stack through native function calls, improving the debugging
experience for WAMR applications on ARM targets.

Signed-off-by: Huang Qi <huangqi3@xiaomi.com>

Author: no1wudi

core/iwasm/common/arch/invokeNative_thumb_vfp.s

@@ -12,7 +12,7 @@ invokeNative:
         .globl _invokeNative
 _invokeNative:
 #endif /* end of BH_PLATFORM_DARWIN */
-
+        .cfi_startproc
 /*
  * Arguments passed in:
  *
@@ -24,10 +24,17 @@ _invokeNative:
         push    {r4, r5, r6, r7}
         push    {lr}
         sub     sp, sp, #4      /* make sp 8 byte aligned */
+        .cfi_def_cfa_offset 24
+        .cfi_offset lr, -20
+        .cfi_offset r4, -16
+        .cfi_offset r5, -12
+        .cfi_offset r6, -8
+        .cfi_offset r7, -4
         mov     ip, r0          /* ip = function ptr */
         mov     r4, r1          /* r4 = argv */
         mov     r5, r2          /* r5 = nstacks */
         mov     r7, sp
+        .cfi_def_cfa r7, 24
 
         /* Fill all int args */
         ldr     r0, [r4, #0]    /* r0 = *(int*)&argv[0] = exec_env */
@@ -57,7 +64,7 @@ _invokeNative:
         vldr    s15, [r4, #60]
         /* Directly call the function if no args in stack */
         cmp     r5, #0
-        beq     call_func
+        beq     .Lcall_func
 
         mov     lr, r2          /* save r2 */
 
@@ -73,30 +80,31 @@ _invokeNative:
         mov     r7, sp
         mov     sp, r6
 
-loop_stack_args:                /* copy stack arguments to stack */
+.Lloop_stack_args:                /* copy stack arguments to stack */
         cmp     r5, #0
-        beq     call_func1
+        beq     .Lcall_func1
         ldr     r2, [r4]         /* Note: caller should insure int64 and */
         add     r4, r4, #4       /* double are placed in 8 bytes aligned address */
         str     r2, [r6]
         add     r6, r6, #4
 
         sub     r5, r5, #1
-        b       loop_stack_args
+        b       .Lloop_stack_args
 
-call_func1:
+.Lcall_func1:
         mov     r2, lr          /* restore r2 */
 
-call_func:
+.Lcall_func:
         blx     ip
         mov     sp, r7          /* restore sp */
 
-return:
+.Lreturn:
         add     sp, sp, #4      /* make sp 8 byte aligned */
         pop     {r3}
         pop     {r4, r5, r6, r7}
         mov     lr, r3
         bx      lr
+        .cfi_endproc
 
 #if defined(__linux__) && defined(__ELF__)
 .section .note.GNU-stack,"",%progbits