[llvm-bugs] [Bug 51735] New: Missing variables after PostOrderFunctionAttrsPass at Og

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=51735

            Bug ID: 51735
           Summary: Missing variables after PostOrderFunctionAttrsPass at
                    Og
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: DebugInfo
          Assignee: unassignedbugs at nondot.org
          Reporter: cristianassaiante at outlook.com
                CC: jdevlieghere at apple.com, keith.walker at arm.com,
                    llvm-bugs at lists.llvm.org,
                    paul_robinson at playstation.sony.com

Upon calling a function from an external module, the variable i passed to it is
not visible from lldb. Using -opt-bisect-limit we discovered that the pass
causing the symbols disappear is "PostOrderFunctionAttrsPass on SCC (main)".

$ cat a.c
void  a()
{
char l_57 = 1;
int l_63 = 2,  i = 0;
for (; i < 8; i++)
;
test_nop();
test_support_3215(l_57, l_63, i);
}
int main ()
{
a();
}

$ cat lib/test.c
#include <stdio.h>
#include <stdint.h>
#include "test.h"

void test_nop() {
    printf("\n");
}

void test_support_3215(int l_57, int l_63, int i) {
    printf("%d %d %d", l_57, l_63, i);
}

$ cat lib/test.h
#pragma once

void test_nop();
void test_support_3215(int l_57, int l_63, int i);

$ clang -v
clang version 13.0.0
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/local/bin
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.5.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/8
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.5.0
Candidate multilib: .;@m64
Selected multilib: .;@m64

$ lldb -v
lldb version 13.0.0

clang revision c2c977ce50597b0e5186afc342c5784bd0aa6973
lldb revision c2c977ce50597b0e5186afc342c5784bd0aa6973

$ clang -g -Og -o opt lib/test.c a.c
$ lldb opt
(lldb) target create "opt"
Current executable set to '/home/cristianrichie/159/reduce/opt' (x86_64).
(lldb) b 7
Breakpoint 1: 2 locations.
(lldb) r
Process 4504 launched: '/home/cristianrichie/159/reduce/opt' (x86_64)
Process 4504 stopped
* thread #1, name = 'opt', stop reason = breakpoint 1.2
    frame #0: 0x0000000000401161 opt`main [inlined] a at a.c:7:1
   4     int l_63 = 2,  i = 0;
   5     for (; i < 8; i++)
   6     ;
-> 7     test_nop();
   8     test_support_3215(l_57, l_63, i);
   9     }
   10    int main ()
(lldb) frame var
(char) l_57 = '\x01'
(int) l_63 = 2
(lldb) frame var i
error: no variable named 'i' found in this frame

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