[llvm-bugs] [Bug 50301] New: Not bug. Performance. Loop optimization. clang++ 1.6x slower than g++

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=50301

            Bug ID: 50301
           Summary: Not bug. Performance. Loop optimization. clang++ 1.6x
                    slower than g++
           Product: new-bugs
           Version: 12.0
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: new bugs
          Assignee: unassignedbugs at nondot.org
          Reporter: h0tc0d3 at gmail.com
                CC: htmldeveloper at gmail.com, llvm-bugs at lists.llvm.org

Created attachment 24850
  --> https://bugs.llvm.org/attachment.cgi?id=24850&action=edit
Affected C++ Source

It this case https://pastebin.com/rhpWvssR

g++ -O2 fib.cpp -o /tmp/fib;clang++ -O2 -fdiagnostics-color=always fib.cpp -o
/tmp/fib2;/tmp/fib;/tmp/fib2

GCC Execution time: 37.622s
Clag Execution time: 61.858s

With OMP and little bit change algo

GCC Execution time: ~23s
Clag Execution time: ~38s

GCC Version 10.2.0
LLVM 11.1.0 and 12.0.0 git branch


This also happens in more complex code. I simplified code for minimal
instructions.

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