[llvm] r206473 - [AArch64] Implement the getCSRFirstUseCost API, mirroring that in ARM64.

[Hal Finkel]

----- Original Message -----
> From: "Manman Ren" <manman.ren at gmail.com>
> To: mcrosier at codeaurora.org
> Cc: "Hal Finkel" <hfinkel at anl.gov>, llvm-commits at cs.uiuc.edu
> Sent: Tuesday, July 1, 2014 3:24:33 PM
> Subject: Re: [llvm] r206473 - [AArch64] Implement the getCSRFirstUseCost API, mirroring that in ARM64.
> 
> 
> 
> 
> I think I checked in a testing case (AArch64/ragreedy-csr.ll)
> 
> ; RUN: llc < %s -mtriple=arm64-apple-ios7.0 -regalloc=greedy
> -regalloc-csr-first-time-cost=15 | FileCheck %s
> 
> 
> ; This testing case is reduced from 197.parser prune_match function.
> ; We make sure that we do not use callee-saved registers (x19 to
> x25).
> ; rdar://16162005
> 
> 
> We can add another RUN line to make sure the testing case can pass
> with a default value of 5.

Okay, that makes sense. I'd also prefer a more artificial test case (as I outlined below, for example), but that's obviously optional ;)

Thanks again,
Hal

> 
> 
> Thanks,
> Manman
> 
> 
> 
> On Tue, Jul 1, 2014 at 7:10 AM, Chad Rosier < mcrosier at codeaurora.org
> > wrote:
> 
> 
> Hi Hal,
> Sorry, I missed the original message. This commit was to the now dead
> AArch64 branch. Ana was just trying to do a competitive analysis
> against the ARM64 (now AArch64) branch. The ARM64 commit, r205248,
> did not have a test case either.
> 
> Manman,
> Can you please add a test case for r205248? Hal has provided one
> below.
> 
> Cjad
> 
> 
> 
> 
> -----Original Message-----
> From: Hal Finkel [mailto: hfinkel at anl.gov ]
> Sent: Monday, June 30, 2014 7:55 PM
> To: Chad Rosier
> Cc: llvm-commits at cs.uiuc.edu
> Subject: Re: [llvm] r206473 - [AArch64] Implement the
> getCSRFirstUseCost API, mirroring that in ARM64.
> 
> Any thoughts on this?
> 
> -Hal
> 
> ----- Original Message -----
> > From: "Hal Finkel" < hfinkel at anl.gov >
> > To: "Chad Rosier" < mcrosier at codeaurora.org >
> > Cc: llvm-commits at cs.uiuc.edu
> > Sent: Sunday, April 20, 2014 10:33:20 PM
> > Subject: Re: [llvm] r206473 - [AArch64] Implement the
> > getCSRFirstUseCost API, mirroring that in ARM64.
> > 
> > Chad,
> > 
> > I understand you're mirroring, but do you have a test case for
> > this?
> > I don't think that Manman had a test case for the original commit
> > either.
> > 
> > If I understand what is going on correctly, it should be easy to
> > make
> > one. You just need something like this:
> > 
> > entry:
> > br i1 undef, label %hot, label %cold
> > 
> > cold:
> > i32 %v = call i32 whatever() ; this value must be saved, and we
> > should spill here instead of using a callee-saved register
> > call void perror(undef) ; just to make this cold; metadata will
> > also work
> > call asm ; clobber all caller-saved registers
> > 
> > hot:
> > %p = phi [0, %entry, %v, %cold]
> > ret i32 %p
> > 
> > -Hal
> > 
> > ----- Original Message -----
> > > From: "Chad Rosier" < mcrosier at codeaurora.org >
> > > To: llvm-commits at cs.uiuc.edu
> > > Sent: Thursday, April 17, 2014 11:19:54 AM
> > > Subject: [llvm] r206473 - [AArch64] Implement the
> > > getCSRFirstUseCost API, mirroring that in ARM64.
> > > 
> > > Author: mcrosier
> > > Date: Thu Apr 17 11:19:54 2014
> > > New Revision: 206473
> > > 
> > > URL: http://llvm.org/viewvc/llvm-project?rev=206473&view=rev
> > > Log:
> > > [AArch64] Implement the getCSRFirstUseCost API, mirroring that in
> > > ARM64.
> > > 
> > > Modified:
> > > llvm/trunk/lib/Target/AArch64/AArch64RegisterInfo.h
> > > 
> > > Modified: llvm/trunk/lib/Target/AArch64/AArch64RegisterInfo.h
> > > URL:
> > > http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/AArch64/AA
> > > rch64RegisterInfo.h?rev=206473&r1=206472&r2=206473&view=diff
> > > ====================================================================
> > > ==========
> > > --- llvm/trunk/lib/Target/AArch64/AArch64RegisterInfo.h
> > > (original)
> > > +++ llvm/trunk/lib/Target/AArch64/AArch64RegisterInfo.h Thu Apr
> > > 17
> > > 11:19:54 2014
> > > @@ -30,6 +30,13 @@ struct AArch64RegisterInfo : public AArc
> > > const MCPhysReg *getCalleeSavedRegs(const MachineFunction *MF =
> > > 0)
> > > const;
> > > const uint32_t *getCallPreservedMask(CallingConv::ID) const;
> > > 
> > > + unsigned getCSRFirstUseCost() const {
> > > + // The cost will be compared against BlockFrequency where
> > > entry
> > > has the
> > > + // value of 1 << 14. A value of 5 will choose to spill or
> > > split
> > > really
> > > + // cold path instead of using a callee-saved register.
> > > + return 5;
> > > + }
> > > +
> > > const uint32_t *getTLSDescCallPreservedMask() const;
> > > 
> > > BitVector getReservedRegs(const MachineFunction &MF) const;
> > > 
> > > 
> > > _______________________________________________
> > > llvm-commits mailing list
> > > llvm-commits at cs.uiuc.edu
> > > http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
> > > 
> > 
> > --
> > Hal Finkel
> > Assistant Computational Scientist
> > Leadership Computing Facility
> > Argonne National Laboratory
> > _______________________________________________
> > llvm-commits mailing list
> > llvm-commits at cs.uiuc.edu
> > http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
> > 
> 
> --
> Hal Finkel
> Assistant Computational Scientist
> Leadership Computing Facility
> Argonne National Laboratory
> 
> 
> 

-- 
Hal Finkel
Assistant Computational Scientist
Leadership Computing Facility
Argonne National Laboratory