From: noone@noone.net   
      
   On Tue 1/6/2026 5:08 AM, Waldek Hebisch wrote:   
   >   
   > I get the following assembly:   
   >   
   > 00000000 :   
   >     0:   b108            cbz     r0, 6    
   >     2:   2000            movs    r0, #0   
   >     4:   4770            bx      lr   
   >     6:   6803            ldr     r3, [r0, #0]   
   >     8:   deff            udf     #255    @ 0xff   
   >     a:   bf00            nop   
   >   
   > So compiler generates actiual access, but then, instead of returning   
   > the value it executes undefined opcode.  Without test for null   
   > pointer I get simple access to memory.   
   >   
      
   When it comes to invalid (or missing, in C++) `return` statements, GCC   
   tends to adhere to a "punitive" approach in optimized code - it injects   
   instructions to deliberately cause a crash/segfault in such cases.   
      
   Clang on the other hand tends to stick to the uniform approach based on   
   the "UB cannot happen" methodology, i.e. your code sample would be   
   translated under "p is never null" assumption, and the function will   
   fold into a simple unconditional `return 0`.   
      
   --   
   Best regards,   
   Andrey   
      
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