[Bug middle-end/119314] Possibly wrong code generation for branch after tail function call

[root at hsnovel dot net]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119314

--- Comment #6 from Novel <root at hsnovel dot net> ---
(In reply to Andrew Pinski from comment #5)
> (In reply to Novel from comment #0)
> 
> > ; CODE XREF from sym.IGNORE_THIS_ITS_FUNCTION_NAME @ 0x8bcc(x)
> > ; 0x28f58                                                  
> > lea rdi, section..got                                      
> > call fcn.00006260;[ob]                                     
> > ; int64_t arg3                                             
> > mov rdx, rbp                                               
> > ; int64_t arg1                                             
> > mov edi, 2                                                 
> > ; int64_t arg2                                             
> > ; 0x234e6                                                  
> > ; "2 Data %p\n"                                            
> > lea rsi, str.2_Data__p_n                                   
> > mov rax, qword [rax]                                       
> > add rbx, qword [rax + 0x10]                                
> > xor eax, eax                                               
> > mov r13, qword [rbx + 8]                                   
> > mov ebx, dword [rbx + 0x10]                                
> > call sym.log_log;[oa]                                      
> > xor eax, eax                                               
> > ; int64_t arg3                                             
> > mov edx, r14d                                              
> > ; int64_t arg1                                             
> > mov edi, 2                                                 
> > ; int64_t arg2                                             
> > ; 0x234f1                                                  
> > ; "2 Size %d\n"                                            
> > lea rsi, str.2_Size__d_n                                   
> > call sym.log_log;[oa]                                      
> > test rbp, rbp                                              
> > je 0x8a98
> 
> Test %RBP .
> 
> So if a function does not restore correctly %RBP things could go wrong. 
> 
> Also try running your test program under valgrind, it might catch some stuff
> too.
> 
> The other thing to try is change log_info to be a just printf.
> 
> There could be a bug in musl fprintf too that is not restoring some register
> correctly. It is not obvious what is going on here from even the snip of
> code.

I tested it today and neither valgrind nor sanitizer did report anyhting
related to this.

I did link with glibc, instead of musl and tested printf but it's still the
same.

I am not sure if further discussion in this report would be usefull to any gcc
maintainer, as I am not able to provide much information unfortunately.

I can test other things, if some maintainer wants me to experiment with some
flag somehow, otherwise you can close this report when you see fit.