[llvm] r245907 - [PowerPC] PPCVSXFMAMutate should ignore trivial-copy addends

[Hans Wennborg via llvm-commits]

+Tom for 3.7.1

On Wed, Aug 26, 2015 at 4:21 PM, Hans Wennborg <hans at chromium.org> wrote:
> Hi Hal,
>
> While there will be an rc4, I would rather not merge this as it's late
> in the process and I want to keep the number of merges to a minimum.
> It will be an excellent patch to get for 3.7.1.
>
> Thanks,
> Hans
>
> On Mon, Aug 24, 2015 at 4:56 PM, Hans Wennborg <hans at chromium.org> wrote:
>> Noted. :-)
>>
>> On Mon, Aug 24, 2015 at 4:50 PM, Hal Finkel <hfinkel at anl.gov> wrote:
>>> Hi Hans,
>>>
>>> If there is another RC, this one too please.
>>>
>>> Thanks again,
>>> Hal
>>>
>>> ----- Original Message -----
>>>> From: "Hal Finkel via llvm-commits" <llvm-commits at lists.llvm.org>
>>>> To: llvm-commits at lists.llvm.org
>>>> Sent: Monday, August 24, 2015 6:48:28 PM
>>>> Subject: [llvm] r245907 - [PowerPC] PPCVSXFMAMutate should ignore trivial-copy addends
>>>>
>>>> Author: hfinkel
>>>> Date: Mon Aug 24 18:48:28 2015
>>>> New Revision: 245907
>>>>
>>>> URL: http://llvm.org/viewvc/llvm-project?rev=245907&view=rev
>>>> Log:
>>>> [PowerPC] PPCVSXFMAMutate should ignore trivial-copy addends
>>>>
>>>> We might end up with a trivial copy as the addend, and if so, we
>>>> should ignore
>>>> the corresponding FMA instruction. The trivial copy can be coalesced
>>>> away later,
>>>> so there's nothing to do here. We should not, however, assert. Fixes
>>>> PR24544.
>>>>
>>>> Added:
>>>>     llvm/trunk/test/CodeGen/PowerPC/vsx-fma-mutate-trivial-copy.ll
>>>> Modified:
>>>>     llvm/trunk/lib/Target/PowerPC/PPCVSXFMAMutate.cpp
>>>>
>>>> Modified: llvm/trunk/lib/Target/PowerPC/PPCVSXFMAMutate.cpp
>>>> URL:
>>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/PowerPC/PPCVSXFMAMutate.cpp?rev=245907&r1=245906&r2=245907&view=diff
>>>> ==============================================================================
>>>> --- llvm/trunk/lib/Target/PowerPC/PPCVSXFMAMutate.cpp (original)
>>>> +++ llvm/trunk/lib/Target/PowerPC/PPCVSXFMAMutate.cpp Mon Aug 24
>>>> 18:48:28 2015
>>>> @@ -186,11 +186,14 @@ protected:
>>>>          if (!KilledProdOp)
>>>>            continue;
>>>>
>>>> -        // For virtual registers, verify that the addend source
>>>> register
>>>> -        // is live here (as should have been assured above).
>>>> -        assert((!TargetRegisterInfo::isVirtualRegister(AddendSrcReg)
>>>> ||
>>>> -                LIS->getInterval(AddendSrcReg).liveAt(FMAIdx)) &&
>>>> -               "Addend source register is not live!");
>>>> +     // If the addend copy is used only by this MI, then the addend
>>>> source
>>>> +     // register is likely not live here. This could be fixed (based on
>>>> the
>>>> +     // legality checks above, the live range for the addend source
>>>> register
>>>> +     // could be extended), but it seems likely that such a trivial copy
>>>> can
>>>> +     // be coalesced away later, and thus is not worth the effort.
>>>> +     if (TargetRegisterInfo::isVirtualRegister(AddendSrcReg) &&
>>>> +            !LIS->getInterval(AddendSrcReg).liveAt(FMAIdx))
>>>> +          continue;
>>>>
>>>>          // Transform: (O2 * O3) + O1 -> (O2 * O1) + O3.
>>>>
>>>>
>>>> Added: llvm/trunk/test/CodeGen/PowerPC/vsx-fma-mutate-trivial-copy.ll
>>>> URL:
>>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/PowerPC/vsx-fma-mutate-trivial-copy.ll?rev=245907&view=auto
>>>> ==============================================================================
>>>> --- llvm/trunk/test/CodeGen/PowerPC/vsx-fma-mutate-trivial-copy.ll
>>>> (added)
>>>> +++ llvm/trunk/test/CodeGen/PowerPC/vsx-fma-mutate-trivial-copy.ll
>>>> Mon Aug 24 18:48:28 2015
>>>> @@ -0,0 +1,38 @@
>>>> +; RUN: llc < %s | FileCheck %s
>>>> +target datalayout = "E-m:e-i64:64-n32:64"
>>>> +target triple = "powerpc64-unknown-linux-gnu"
>>>> +
>>>> +; Function Attrs: nounwind
>>>> +define void @LSH_recall_init(float %d_min, float %W) #0 {
>>>> +entry:
>>>> +  br i1 undef, label %for.body.lr.ph, label %for.end
>>>> +
>>>> +; CHECK-LABEL: @LSH_recall_init
>>>> +; CHECK: xsnmsubadp
>>>> +
>>>> +for.body.lr.ph:                                   ; preds = %entry
>>>> +  %conv3 = fpext float %W to double
>>>> +  br label %for.body
>>>> +
>>>> +for.body:                                         ; preds =
>>>> %for.body, %for.body.lr.ph
>>>> +  %div = fdiv fast float 0.000000e+00, 0.000000e+00
>>>> +  %add = fadd fast float %div, %d_min
>>>> +  %conv2 = fpext float %add to double
>>>> +  %0 = tail call double @llvm.sqrt.f64(double %conv2)
>>>> +  %div4 = fdiv fast double %conv3, %0
>>>> +  %call = tail call signext i32 bitcast (i32 (...)* @p_col_helper to
>>>> i32 (double)*)(double %div4) #2
>>>> +  br label %for.body
>>>> +
>>>> +for.end:                                          ; preds = %entry
>>>> +  ret void
>>>> +}
>>>> +
>>>> +; Function Attrs: nounwind readnone
>>>> +declare double @llvm.sqrt.f64(double) #1
>>>> +
>>>> +declare signext i32 @p_col_helper(...) #2
>>>> +
>>>> +attributes #0 = { nounwind "no-infs-fp-math"="true"
>>>> "no-nans-fp-math"="true" "target-cpu"="pwr7" "unsafe-fp-math"="true"
>>>> }
>>>> +attributes #1 = { nounwind readnone }
>>>> +attributes #2 = { nounwind }
>>>> +
>>>>
>>>>
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>>>>
>>>
>>> --
>>> Hal Finkel
>>> Assistant Computational Scientist
>>> Leadership Computing Facility
>>> Argonne National Laboratory