[Bug rtl-optimization/19705] New: [4.0 Regression] cannot turn off doloop optimization via -fno-branch-count-reg if -fno-ivopts is also supplied

[Bug rtl-optimization/19705] New: [4.0 Regression] cannot turn off doloop optimization via -fno-branch-count-reg if -fno-ivopts is also supplied

[pinskia at gcc dot gnu dot org]

Hmm, this is werid, why cannot I turn off doloop optimization with the -fno-branch-count-reg when I 
also turn off ivopts?  I should be able to when I want to look at the interaction between those two 
optimizations (options).
Testcase:
int foo (int x)
{
    int i= x;
    do {
        x *= 2;
    } while (--i);
    return x;
}

Compile with -O2 -fno-branch-count-reg -fno-ivopts and see there still is a bdnz in there.
but compile with -O2 -fno-branch-count-reg and you don't get the bdnz.

-- 
           Summary: [4.0 Regression] cannot turn off doloop optimization via
                    -fno-branch-count-reg if -fno-ivopts is also supplied
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Severity: minor
          Priority: P2
         Component: rtl-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: pinskia at gcc dot gnu dot org
                CC: gcc-bugs at gcc dot gnu dot org
GCC target triplet: powerpc-*-darwin*


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19705

[Bug rtl-optimization/19705] Cannot turn off doloop optimization via -fno-branch-count-reg if -fno-ivopts is also supplied

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-01-30 06:08 -------
Werid it is combine which is doing it.  Hmm and this is not a regression.

Either the documention needs updating or the targets need to turn off these patterns when -fno-
branch-count-reg is supplied.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |documentation
            Summary|[4.0 Regression] cannot turn|Cannot turn off doloop
                   |off doloop optimization via |optimization via -fno-
                   |-fno-branch-count-reg if -  |branch-count-reg if -fno-
                   |fno-ivopts is also supplied |ivopts is also supplied


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19705

[Bug rtl-optimization/19705] Cannot turn off doloop optimization via -fno-branch-count-reg if -fno-ivopts is also supplied

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-02-20 14:17 -------
Confirmed, the documention just needs to changed as that -fno-branch-count-reg only turns off the 
extra analysis and that you can still get code using the branch counter even when using this option.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
   Last reconfirmed|0000-00-00 00:00:00         |2005-02-20 14:17:17
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19705

[Bug rtl-optimization/19705] Cannot turn off doloop optimization via -fno-branch-count-reg if -fno-ivopts is also supplied

[amodra at bigpond dot net dot au]

------- Additional Comments From amodra at bigpond dot net dot au  2005-09-01 14:05 -------
Or make the doloop insn patterns conditional on flag_branch_on_count_reg?

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19705