[llvm-bugs] [Bug 51782] New: Missing variables after SimplifyCFG at O2

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=51782

            Bug ID: 51782
           Summary: Missing variables after SimplifyCFG at O2
           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 first 9 variables passed
to it are not visible from lldb. Using -opt-bisect-limit we discovered that the
pass causing the symbols disappear is "SimplifyCFGPass on function (main)"

$ cat a.c
int b ;
static int a()
{
char l_287 = 1,  l_342 = 5;
int l_326 = 0,  l_341 = 1,  l_363 = 0,  l_387 = 3,  l_436 = 0,  i, j;
short l_343 = 3,  l_412 = 0,  l_413 = 1;
i = 0;
for (; i < 2; i++)
{
j = 0;
for (; j < 7; j++)
{
test_nop();
test_support_3073(l_287, l_326, l_341, l_342, l_343, l_363, l_387, l_412,
l_413, l_436, i, j);
}
}
}
int main ()
{
for (; b < 10; b++)
a();
}

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

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

void test_support_3073(int l_287, int l_326, int l_341, int l_342, int l_343,
int l_363, int l_387, int l_412, int l_413, int l_436, int i, int j) {
    printf("%d %d %d %d %d %d %d %d %d %d %d %d", l_287, l_326, l_341, l_342,
l_343, l_363, l_387, l_412, l_413, l_436, i, j);

}

$ cat lib/test.h
#pragma once

void test_nop();

void test_support_3073(int l_287, int l_326, int l_341, int l_342, int l_343,
int l_363, int l_387, int l_412, int l_413, int l_436, int i, int j);

$ 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 -O2 -o opt lib/test.c a.c
$ lldb opt
(lldb) target create "opt"
Current executable set to '/home/cristianrichie/276/reduce/opt' (x86_64).
(lldb) b 13
Breakpoint 1: where = opt`main + 32 [inlined] a at a.c:13:1, address =
0x0000000000401160
(lldb) r
Process 2122 launched: '/home/cristianrichie/276/reduce/opt' (x86_64)
Process 2122 stopped
* thread #1, name = 'opt', stop reason = breakpoint 1.1
    frame #0: 0x0000000000401160 opt`main [inlined] a at a.c:13:1
   10   j = 0;
   11   for (; j < 7; j++)
   12   {
-> 13   test_nop();
   14   test_support_3073(l_287, l_326, l_341, l_342, l_343, l_363, l_387,
l_412, l_413, l_436, i, j);
   15   }
   16   }
(lldb) frame var
(int) i = 0
(int) j = 0
(lldb) frame var l_287
error: no variable named 'l_287' found in this frame
(lldb) frame var l_326
error: no variable named 'l_326' found in this frame
(lldb) frame var l_341
error: no variable named 'l_341' found in this frame
(lldb) frame var l_342
error: no variable named 'l_342' found in this frame
(lldb) frame var l_343
error: no variable named 'l_343' found in this frame
(lldb) frame var l_363
error: no variable named 'l_363' found in this frame
(lldb) frame var l_387
error: no variable named 'l_387' found in this frame
(lldb) frame var l_412
error: no variable named 'l_412' found in this frame
(lldb) frame var l_413
error: no variable named 'l_413' found in this frame

-- 
You are receiving this mail because:
You are on the CC list for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-bugs/attachments/20210907/00d6253a/attachment.html>