[llvm-bugs] [Bug 50474] New: wrong code caused by "-early-cse -instsimplify -jump-threading -constraint-elimination"

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=50474

            Bug ID: 50474
           Summary: wrong code caused by "-early-cse -instsimplify
                    -jump-threading -constraint-elimination"
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Scalar Optimizations
          Assignee: unassignedbugs at nondot.org
          Reporter: cszide at 163.com
                CC: llvm-bugs at lists.llvm.org

Created attachment 24889
  --> https://bugs.llvm.org/attachment.cgi?id=24889&action=edit
small.bc

$clang -v
clang version 13.0.0 (https://github.com/llvm/llvm-project.git
d56729b4a4393da9c65bdfe762b51f8b7b0ce0ca)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/oscar/compiler/llvm-project/build/bin
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/10
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8.5
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/10
Candidate multilib: .;@m64
Selected multilib: .;@m64

$gcc small.c && ./a.out

$clang -O3 -c -emit-llvm  -femit-all-decls -mllvm -disable-llvm-optzns small.c

$opt -early-cse -instsimplify -jump-threading -constraint-elimination small.bc
-o small-opt.bc

$clang small-opt.bc && ./a.out
hello!

---------------------------------------
#include<stdio.h>
char a;
void main() {
  int b = a ?: a;
  if (b)
    printf("hello!\n");
}

-- 
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/20210526/60ddfc62/attachment.html>