[LLVMdev] strange dbgs() behavior: unable to print floats in machine backend

[Craig Topper]

Can you try making the constructor "explicit" for PrintReg in
include/llvm/Target/TargetRegisterInfo.h. I think you were getting an
implicit conversion there which should probably be fixed anyway.

On Mon, Nov 26, 2012 at 11:47 PM, Bjorn De Sutter <
bjorn.desutter at elis.ugent.be> wrote:

> Hi,
>
> that solved my problem on trunk as well, thanks. Strange that you have to
> include this though.
>
> Bjorn
>
> On 27 Nov 2012, at 00:00, Daniel Prokesch <daniel.prokesch at gmail.com>
> wrote:
>
> > Hi,
> >
> > I accidentally stumbled upon your post.
> > I observed similar behaviour whenever I did not include
> >
> > #include "llvm/Support/Debug.h"
> > #include "llvm/Support/raw_ostream.h"
> >
> > I'm working on release 3.1 though.
> >
> > hth, Daniel
> >
> > On 11/26/2012 03:00 PM, Bjorn De Sutter wrote:
> >> Hi,
> >>
> >> I am trying to debug my backend, and observe very strange behavior with
> dbgs():
> >>
> >> In the IfConverter, I have added two debugging lines that print
> floating-point numbers for the sake of demonstration that such printing
> works fine.
> >>
> >> bool MeetIfcvtSizeLimit(MachineBasicBlock &BB,
> >>                             unsigned Cycle, unsigned Extra,
> >>                             const BranchProbability &Prediction) const {
> >>
> >>                 dbgs() << "OOPS " << 1.14 << "\n";
> >>                 bool flag =  Cycle > 0 && TII->isProfitableToIfCvt(BB,
> Cycle, Extra,
> >>                                                    Prediction);
> >>                 dbgs() << "OOPS " << 1.15 << "\n";
> >>       return flag;
> >>     }
> >>
> >> This method invokes the backend method
> >>
> >> bool ADRESInstrInfo::isProfitableToIfCvt(MachineBasicBlock &MBB,
> unsigned NumCycles, unsigned ExtraPredCycles,
> >>                                          const BranchProbability
> &Probability) const {
> >>      dbgs() << "OOPS " << 1.16 << "\n";
> >> }
> >>
> >> This invocation works as it should (verified with gdb). But when I
> execute this code fragment, I get
> >>
> >> OOPS 1.140000e+00
> >> OOPS %physreg1
> >> OOPS 1.150000e+00
> >>
> >> So suddenly in the machine backend, the dbgs() ostream (which is still
> the very same ostream as in the IfConverter, I checked the address with
> gdb) prints floating point numbers as if they are physical registers. Any
> idea what is going on or how I can force floating-point numbers to be
> printed in the backend code? I want to do that to tune my if-predication
> heuristics ...
> >>
> >> By the way, when I step through the isProfitableToIfCvt method, rather
> than invoking a <<-operator in an ostream class, the constructor of the
> Twine class is invoked ...
> >>
> >> Thanks,
> >>
> >> Bjorn De Sutter
> >> Computer Systems Lab
> >> Ghent University
> >>
> >>
> >>
> >>
> >>
> >> _______________________________________________
> >> LLVM Developers mailing list
> >> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> >> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
> >
>
>
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-- 
~Craig
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