[llvm] r265493 - [SLPVectorizer] Vectorize libcalls of sqrt
David Majnemer via llvm-commits
llvm-commits at lists.llvm.org
Wed Apr 6 00:10:55 PDT 2016
On Tue, Apr 5, 2016 at 8:23 PM, Hal Finkel <hfinkel at anl.gov> wrote:
> ----- Original Message -----
> > From: "David Majnemer via llvm-commits" <llvm-commits at lists.llvm.org>
> > To: llvm-commits at lists.llvm.org
> > Sent: Tuesday, April 5, 2016 7:15:01 PM
> > Subject: [llvm] r265493 - [SLPVectorizer] Vectorize libcalls of sqrt
> >
> > Author: majnemer
> > Date: Tue Apr 5 19:14:59 2016
> > New Revision: 265493
> >
> > URL: http://llvm.org/viewvc/llvm-project?rev=265493&view=rev
> > Log:
> > [SLPVectorizer] Vectorize libcalls of sqrt
> >
> > We didn't realize that we could transform the libcall into a
> > vectorized
> > intrinsic.
>
> But, as I recall, we can't. The problem is that our sqrt intrinsic is a
> special case: it has different UB-related semantics than the libcall.
> Specifically, the LangRef says, "Unlike sqrt in libm, however, llvm.sqrt
> has undefined behavior for negative numbers other than -0.0 (which allows
> for better optimization, because there is no need to worry about errno
> being set). llvm.sqrt(-0.0) is defined to return -0.0 like IEEE sqrt."
>
> We can do this if we're in no-NaNs mode.
>
Ah, good call. Fixed in r265521.
>
> -Hal
>
> >
> > Modified:
> > llvm/trunk/lib/Analysis/VectorUtils.cpp
> > llvm/trunk/test/Transforms/LoopVectorize/X86/veclib-calls.ll
> > llvm/trunk/test/Transforms/SLPVectorizer/X86/call.ll
> >
> > Modified: llvm/trunk/lib/Analysis/VectorUtils.cpp
> > URL:
> >
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/VectorUtils.cpp?rev=265493&r1=265492&r2=265493&view=diff
> >
> ==============================================================================
> > --- llvm/trunk/lib/Analysis/VectorUtils.cpp (original)
> > +++ llvm/trunk/lib/Analysis/VectorUtils.cpp Tue Apr 5 19:14:59 2016
> > @@ -220,6 +220,10 @@ Intrinsic::ID llvm::getIntrinsicIDForCal
> > case LibFunc::powf:
> > case LibFunc::powl:
> > return checkBinaryFloatSignature(*CI, Intrinsic::pow);
> > + case LibFunc::sqrt:
> > + case LibFunc::sqrtf:
> > + case LibFunc::sqrtl:
> > + return checkUnaryFloatSignature(*CI, Intrinsic::sqrt);
> > }
> >
> > return Intrinsic::not_intrinsic;
> >
> > Modified:
> > llvm/trunk/test/Transforms/LoopVectorize/X86/veclib-calls.ll
> > URL:
> >
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopVectorize/X86/veclib-calls.ll?rev=265493&r1=265492&r2=265493&view=diff
> >
> ==============================================================================
> > --- llvm/trunk/test/Transforms/LoopVectorize/X86/veclib-calls.ll
> > (original)
> > +++ llvm/trunk/test/Transforms/LoopVectorize/X86/veclib-calls.ll Tue
> > Apr 5 19:14:59 2016
> > @@ -3,31 +3,6 @@
> > target datalayout =
> >
> "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
> > target triple = "x86_64-unknown-linux-gnu"
> >
> > -;CHECK-LABEL: @sqrt_f32(
> > -;CHECK: vsqrtf{{.*}}<4 x float>
> > -;CHECK: ret void
> > -declare float @sqrtf(float) nounwind readnone
> > -define void @sqrt_f32(i32 %n, float* noalias %y, float* noalias %x)
> > nounwind uwtable {
> > -entry:
> > - %cmp6 = icmp sgt i32 %n, 0
> > - br i1 %cmp6, label %for.body, label %for.end
> > -
> > -for.body: ; preds = %entry,
> > %for.body
> > - %indvars.iv = phi i64 [ %indvars.iv.next, %for.body ], [ 0, %entry
> > ]
> > - %arrayidx = getelementptr inbounds float, float* %y, i64
> > %indvars.iv
> > - %0 = load float, float* %arrayidx, align 4
> > - %call = tail call float @sqrtf(float %0) nounwind readnone
> > - %arrayidx2 = getelementptr inbounds float, float* %x, i64
> > %indvars.iv
> > - store float %call, float* %arrayidx2, align 4
> > - %indvars.iv.next = add i64 %indvars.iv, 1
> > - %lftr.wideiv = trunc i64 %indvars.iv.next to i32
> > - %exitcond = icmp eq i32 %lftr.wideiv, %n
> > - br i1 %exitcond, label %for.end, label %for.body
> > -
> > -for.end: ; preds =
> > %for.body, %entry
> > - ret void
> > -}
> > -
> > ;CHECK-LABEL: @exp_f32(
> > ;CHECK: vexpf{{.*}}<4 x float>
> > ;CHECK: ret void
> > @@ -160,6 +135,7 @@ for.end:
> > ;CHECK-LABEL: @sqrt_f32_nobuiltin(
> > ;CHECK-NOT: vsqrtf{{.*}}<4 x float>
> > ;CHECK: ret void
> > +declare float @sqrtf(float) nounwind readnone
> > define void @sqrt_f32_nobuiltin(i32 %n, float* noalias %y, float*
> > noalias %x) nounwind uwtable {
> > entry:
> > %cmp6 = icmp sgt i32 %n, 0
> >
> > Modified: llvm/trunk/test/Transforms/SLPVectorizer/X86/call.ll
> > URL:
> >
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SLPVectorizer/X86/call.ll?rev=265493&r1=265492&r2=265493&view=diff
> >
> ==============================================================================
> > --- llvm/trunk/test/Transforms/SLPVectorizer/X86/call.ll (original)
> > +++ llvm/trunk/test/Transforms/SLPVectorizer/X86/call.ll Tue Apr 5
> > 19:14:59 2016
> > @@ -7,6 +7,7 @@ declare double @sin(double)
> > declare double @cos(double)
> > declare double @pow(double, double)
> > declare double @exp2(double)
> > +declare double @sqrt(double)
> > declare i64 @round(i64)
> >
> >
> > @@ -92,6 +93,28 @@ entry:
> > store double %call, double* %c, align 8
> > %arrayidx5 = getelementptr inbounds double, double* %c, i64 1
> > store double %call5, double* %arrayidx5, align 8
> > + ret void
> > +}
> > +
> > +
> > +; CHECK: sqrt_libm
> > +; CHECK: call <2 x double> @llvm.sqrt.v2f64
> > +; CHECK: ret void
> > +define void @sqrt_libm(double* %a, double* %b, double* %c) {
> > +entry:
> > + %i0 = load double, double* %a, align 8
> > + %i1 = load double, double* %b, align 8
> > + %mul = fmul double %i0, %i1
> > + %call = tail call double @sqrt(double %mul) nounwind readnone
> > + %arrayidx3 = getelementptr inbounds double, double* %a, i64 1
> > + %i3 = load double, double* %arrayidx3, align 8
> > + %arrayidx4 = getelementptr inbounds double, double* %b, i64 1
> > + %i4 = load double, double* %arrayidx4, align 8
> > + %mul5 = fmul double %i3, %i4
> > + %call5 = tail call double @sqrt(double %mul5) nounwind readnone
> > + store double %call, double* %c, align 8
> > + %arrayidx5 = getelementptr inbounds double, double* %c, i64 1
> > + store double %call5, double* %arrayidx5, align 8
> > ret void
> > }
> >
> >
> >
> > _______________________________________________
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> > llvm-commits at lists.llvm.org
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> >
>
> --
> Hal Finkel
> Assistant Computational Scientist
> Leadership Computing Facility
> Argonne National Laboratory
>
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