Hi PPL i developed a plugin that produces the following gimple
test ()
{
int selected_fnc_var_.3;
int random_Var.2;
int D.2363;
int _1;
<bb 2>:
random_Var.2_2 = rand ();
selected_fnc_var_.3_3 = random_Var.2_2 %[fl] 5;
if (selected_fnc_var_.3_3 == 4) goto <L7>;
if (selected_fnc_var_.3_3 == 3) goto <L6>;
if (selected_fnc_var_.3_3 == 2) goto <L5>;
if (selected_fnc_var_.3_3 == 1) goto <L4>;
if (selected_fnc_var_.3_3 == 0) goto <L3>;
<L7>:
_1 = f.clone.4 ("t", "t");
goto <L8>;
<L6>:
_1 = f.clone.3 ("t", "t");
goto <L8>;
<L5>:
_1 = f.clone.2 ("t", "t");
goto <L8>;
<L4>:
_1 =f.clone.1 ("t", "t");
goto <L8>;
<L8>:
if (_1 != 0)
goto <bb 3>;
else
goto <bb 4>;
<bb 3>:
__builtin_puts (&" f success "[0]);
goto <bb 5>;
<bb 4>:
__builtin_puts (&" f failed "[0]);
<bb 5>:
return;
}
with this final code
00000000004005c6 <test>:
4005c6: 55 push %rbp
4005c7: 48 89 e5 mov %rsp,%rbp
4005ca: 53 push %rbx
4005cb: 48 83 ec 08 sub $0x8,%rsp
4005cf: e8 6c fe ff ff callq 400440 <rand@plt>
4005d4: 89 d9 mov %ebx,%ecx
4005d6: c1 f9 1f sar $0x1f,%ecx
4005d9: 89 d8 mov %ebx,%eax
4005db: 31 c8 xor %ecx,%eax
4005dd: ba 67 66 66 66 mov $0x66666667,%edx
4005e2: f7 e2 mul %edx
4005e4: 89 d0 mov %edx,%eax
4005e6: d1 e8 shr %eax
4005e8: 31 c8 xor %ecx,%eax
4005ea: 89 c2 mov %eax,%edx
4005ec: c1 e2 02 shl $0x2,%edx
4005ef: 01 c2 add %eax,%edx
4005f1: 89 d8 mov %ebx,%eax
4005f3: 29 d0 sub %edx,%eax
4005f5: 83 f8 04 cmp $0x4,%eax
4005f8: 75 32 jne 40062c <test+0x66>
4005fa: 83 f8 03 cmp $0x3,%eax
4005fd: 74 2d je 40062c <test+0x66>
4005ff: 83 f8 02 cmp $0x2,%eax
400602: 74 28 je 40062c <test+0x66>
400604: 83 f8 01 cmp $0x1,%eax
400607: 74 23 je 40062c <test+0x66>
400609: 85 c0 test %eax,%eax
40060b: 74 1f je 40062c <test+0x66>
40060d: be bc 09 40 00 mov $0x4009bc,%esi
400612: bf c6 09 40 00 mov $0x4009c6,%edi
400617: e8 7d 02 00 00 callq 400899 <f.clone.4>
40061c: 85 c0 test %eax,%eax
40061e: 75 0c jne 40062c <test+0x66>
400620: bf d0 09 40 00 mov $0x4009d0,%edi
400625: e8 e6 fd ff ff callq 400410 <puts@plt>
40062a: eb 0a jmp 400636 <test+0x70>
40062c: bf e8 09 40 00 mov $0x4009e8,%edi
400631: e8 da fd ff ff callq 400410 <puts@plt>
400636: 48 83 c4 08 add $0x8,%rsp
40063a: 5b pop %rbx
40063b: 5d pop %rbp
40063c: c3 retq
from this gimple
test(){
int D.2363;
int _1;
<bb 2>:
_1 = f("t", "t");
if (_1 != 0)
goto <bb 3>;
else
goto <bb 4>;
<bb 3>:
__builtin_puts (&" f "[0]);
goto <bb 5>;
<bb 4>:
__builtin_puts (&" f "[0]);
<bb 5>:
return;
}
as you can see in the dis output code, its only make call to f.clone.4
( callq 400899 <f.clone.4> ), i suppose is the dead code elimination
pass is the responsable of this action, i tryed to disable it using -O0
compilation option but without success. my question is how can i make
the compiler produce the final code without deleting those dead codes
portion ( do i need to make any kind of PHI nodes in the labels to
achive that, if so how could i do that ? )
thanks in advance
