refactor: Improve debug experience with CFI directives and proper label naming in Thumb invokeNative (#4719)

This change enhances debugging support and improves assembly code quality:

1. Add CFI (Call Frame Information) directives (.cfi_startproc, .cfi_def_cfa_offset, .cfi_offset, .cfi_endproc) to provide proper call frame information for debuggers
2. Improve label naming by using dot-prefixed conventions (.Lreturn, .Lcall_func, etc.) following assembly best practices

These improvements enhance debugging capabilities and code maintainability while preserving functionality.

Signed-off-by: Huang Qi <[email protected]>

Author: no1wudi

core/iwasm/common/arch/invokeNative_thumb.s

@@ -12,7 +12,7 @@ invokeNative:
         .globl _invokeNative
 _invokeNative:
 #endif /* end of BH_PLATFORM_DARWIN */
-
+        .cfi_startproc
 /*
  * Arguments passed in:
  *
@@ -24,34 +24,40 @@ _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 = argc */
 
         cmp     r5, #1          /* at least one argument required: exec_env */
-        blt     return
+        blt     .Lreturn
 
         mov     r6, #0          /* increased stack size */
 
         ldr     r0, [r4]        /* r0 = argv[0] = exec_env */
         add     r4, r4, #4      /* r4 += 4 */
         cmp     r5, #1
-        beq     call_func
+        beq     .Lcall_func
 
         ldr     r1, [r4]        /* r1 = argv[1] */
         add     r4, r4, #4
         cmp     r5, #2
-        beq     call_func
+        beq     .Lcall_func
 
         ldr     r2, [r4]        /* r2 = argv[2] */
         add     r4, r4, #4
         cmp     r5, #3
-        beq     call_func
+        beq     .Lcall_func
 
         ldr     r3, [r4]        /* r3 = argv[3] */
         add     r4, r4, #4
         cmp     r5, #4
-        beq     call_func
+        beq     .Lcall_func
 
         sub    r5, r5, #4       /* argc -= 4, now we have r0 ~ r3 */
 
@@ -66,29 +72,31 @@ _invokeNative:
         mov     sp, r7
 
         mov     lr, r2          /* save r2 */
-loop_args:                      /* copy left arguments to stack */
+
+.Lloop_args:                      /* copy left arguments to stack */
         cmp     r5, #0
-        beq     call_func1
+        beq     .Lcall_func1
         ldr     r2, [r4]
         add     r4, r4, #4
         str     r2, [r7]
         add     r7, r7, #4
         sub     r5, r5, #1
-        b       loop_args
+        b       .Lloop_args
 
-call_func1:
+.Lcall_func1:
         mov     r2, lr          /* restore r2 */
 
-call_func:
+.Lcall_func:
         blx     ip
         add     sp, sp, r6       /* 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
 #endif