[Bug tree-optimization/103821] New: [12 Regression] huge compile time (jump threading) at -O3 for simple code

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103821

            Bug ID: 103821
           Summary: [12 Regression] huge compile time (jump threading) at
                    -O3 for simple code
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Keywords: compile-time-hog
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pinskia at gcc dot gnu.org
  Target Milestone: ---

Take:
    #include <inttypes.h>
    uint16_t int_sqrt32(uint32_t x)
    {
        uint16_t res=0;
        uint16_t add= 0x8000;   
        do {
            uint16_t temp=res | add;
            uint32_t g2=temp*temp;      
            if (x>=g2)
                res=temp;           
            add>>=1;
        } while(add);
        return res;
    }
----- CUT -----
Compile this at -O3 and GCC takes a long time:
 backwards jump threading           :  20.12 ( 81%)   0.01 ( 50%)  20.12 ( 78%)
   26M ( 79%)