[llvm] r179413 - CostModel: increase the default cost of supported floating point operations from 1 to two. Fixed a few tests that changes because now the cost of one insert + a vector operation on two doubles is lower than two scalar operations on doubles.

[Eric Christopher]

At some point something more than magic numbers would be good. Maybe
an enum or something at least with some accompanying documentation as
to how the magic numbers were gotten. :)

-eric

On Fri, Apr 12, 2013 at 2:15 PM, Nadav Rotem <nrotem at apple.com> wrote:
> Author: nadav
> Date: Fri Apr 12 16:15:03 2013
> New Revision: 179413
>
> URL: http://llvm.org/viewvc/llvm-project?rev=179413&view=rev
> Log:
> CostModel: increase the default cost of supported floating point operations from 1 to two. Fixed a few tests that changes because now the cost of one insert + a vector operation on two doubles is lower than two scalar operations on doubles.
>
>
> Modified:
>     llvm/trunk/lib/CodeGen/BasicTargetTransformInfo.cpp
>     llvm/trunk/test/Analysis/CostModel/X86/arith.ll
>     llvm/trunk/test/Transforms/BBVectorize/X86/loop1.ll
>     llvm/trunk/test/Transforms/BBVectorize/X86/simple.ll
>
> Modified: llvm/trunk/lib/CodeGen/BasicTargetTransformInfo.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/BasicTargetTransformInfo.cpp?rev=179413&r1=179412&r2=179413&view=diff
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/BasicTargetTransformInfo.cpp (original)
> +++ llvm/trunk/lib/CodeGen/BasicTargetTransformInfo.cpp Fri Apr 12 16:15:03 2013
> @@ -204,20 +204,23 @@ unsigned BasicTTI::getArithmeticInstrCos
>
>    std::pair<unsigned, MVT> LT = TLI->getTypeLegalizationCost(Ty);
>
> +  bool IsFloat = Ty->getScalarType()->isFloatingPointTy();
> +  unsigned OpCost = (IsFloat ? 2 : 1);
> +
>    if (TLI->isOperationLegalOrPromote(ISD, LT.second)) {
>      // The operation is legal. Assume it costs 1.
>      // If the type is split to multiple registers, assume that thre is some
>      // overhead to this.
>      // TODO: Once we have extract/insert subvector cost we need to use them.
>      if (LT.first > 1)
> -      return LT.first * 2;
> -    return LT.first * 1;
> +      return LT.first * 2 * OpCost;
> +    return LT.first * 1 * OpCost;
>    }
>
>    if (!TLI->isOperationExpand(ISD, LT.second)) {
>      // If the operation is custom lowered then assume
>      // thare the code is twice as expensive.
> -    return LT.first * 2;
> +    return LT.first * 2 * OpCost;
>    }
>
>    // Else, assume that we need to scalarize this op.
> @@ -230,7 +233,7 @@ unsigned BasicTTI::getArithmeticInstrCos
>    }
>
>    // We don't know anything about this scalar instruction.
> -  return 1;
> +  return OpCost;
>  }
>
>  unsigned BasicTTI::getShuffleCost(ShuffleKind Kind, Type *Tp, int Index,
>
> Modified: llvm/trunk/test/Analysis/CostModel/X86/arith.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/CostModel/X86/arith.ll?rev=179413&r1=179412&r2=179413&view=diff
> ==============================================================================
> --- llvm/trunk/test/Analysis/CostModel/X86/arith.ll (original)
> +++ llvm/trunk/test/Analysis/CostModel/X86/arith.ll Fri Apr 12 16:15:03 2013
> @@ -66,9 +66,9 @@ define void @avx2mull() {
>
>  ; CHECK: fmul
>  define i32 @fmul(i32 %arg) {
> -  ;CHECK: cost of 1 {{.*}} fmul
> +  ;CHECK: cost of 2 {{.*}} fmul
>    %A = fmul <4 x float> undef, undef
> -  ;CHECK: cost of 1 {{.*}} fmul
> +  ;CHECK: cost of 2 {{.*}} fmul
>    %B = fmul <8 x float> undef, undef
>    ret i32 undef
>  }
>
> Modified: llvm/trunk/test/Transforms/BBVectorize/X86/loop1.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/BBVectorize/X86/loop1.ll?rev=179413&r1=179412&r2=179413&view=diff
> ==============================================================================
> --- llvm/trunk/test/Transforms/BBVectorize/X86/loop1.ll (original)
> +++ llvm/trunk/test/Transforms/BBVectorize/X86/loop1.ll Fri Apr 12 16:15:03 2013
> @@ -34,7 +34,15 @@ for.body:
>    %lftr.wideiv = trunc i64 %indvars.iv.next to i32
>    %exitcond = icmp eq i32 %lftr.wideiv, 10
>    br i1 %exitcond, label %for.end, label %for.body
> -; CHECK-NOT: <2 x double>
> +; CHECK: insertelement
> +; CHECK-NEXT: insertelement
> +; CHECK-NEXT: fadd <2 x double>
> +; CHECK-NEXT: insertelement
> +; CHECK-NEXT: insertelement
> +; CHECK-NEXT: fadd <2 x double>
> +; CHECK-NEXT: insertelement
> +; CHECK-NEXT: fmul <2 x double>
> +
>  ; CHECK-UNRL: %mul = fmul <2 x double> %2, %2
>  ; CHECK-UNRL: %mul3 = fmul <2 x double> %2, %3
>  ; CHECK-UNRL: %add = fadd <2 x double> %mul, %mul3
>
> Modified: llvm/trunk/test/Transforms/BBVectorize/X86/simple.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/BBVectorize/X86/simple.ll?rev=179413&r1=179412&r2=179413&view=diff
> ==============================================================================
> --- llvm/trunk/test/Transforms/BBVectorize/X86/simple.ll (original)
> +++ llvm/trunk/test/Transforms/BBVectorize/X86/simple.ll Fri Apr 12 16:15:03 2013
> @@ -12,7 +12,11 @@ define double @test1(double %A1, double
>         %R  = fmul double %Z1, %Z2
>         ret double %R
>  ; CHECK: @test1
> -; CHECK-NOT: fmul <2 x double>
> +; CHECK: fsub <2 x double>
> +; CHECK: fmul <2 x double>
> +; CHECK: fadd <2 x double>
> +; CHECK: extract
> +; CHECK: extract
>  ; CHECK: ret double %R
>  }
>
> @@ -63,7 +67,12 @@ define double @test2(double %A1, double
>         %R  = fmul double %Z1, %Z2
>         ret double %R
>  ; CHECK: @test2
> -; CHECK-NOT: fmul <2 x double>
> +; CHECK: insertelement
> +; CHECK: insertelement
> +; CHECK: insertelement
> +; CHECK: insertelement
> +; CHECK: fsub <2 x double>
> +; CHECK: fmul <2 x double>
>  ; CHECK: ret double %R
>  }
>
> @@ -80,7 +89,15 @@ define double @test4(double %A1, double
>         %R  = fmul double %Z1, %Z2
>         ret double %R
>  ; CHECK: @test4
> -; CHECK-NOT: fmul <2 x double>
> +; CHECK: insertelement
> +; CHECK: insertelement
> +; CHECK: insertelement
> +; CHECK: insertelement
> +; CHECK: fsub <2 x double>
> +; CHECK: fmul <2 x double>
> +; CHECK: insertelement
> +; CHECK: insertelement
> +; CHECK: fadd <2 x double>
>  ; CHECK: ret double %R
>  }
>
>
>
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