[llvm] r265493 - [SLPVectorizer] Vectorize libcalls of sqrt
Hal Finkel via llvm-commits
llvm-commits at lists.llvm.org
Tue Apr 5 20:23:09 PDT 2016
----- 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.
-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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--
Hal Finkel
Assistant Computational Scientist
Leadership Computing Facility
Argonne National Laboratory
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