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[ARM] Make f16 interleaved accesses expensive. 

There are no vldN/vstN f16 variants, even with +fullfp16.
We could use the i16 variants, but, in practice, even with +fullfp16,
the f16 sequence leading to the i16 shuffle usually gets scalarized.
We'd need to improve our support for f16 codegen before getting there.

Teach the cost model to consider f16 interleaved operations as
expensive.  Otherwise, we are all but guaranteed to end up with
a large block of scalarized vector code.

llvm-svn: 294819
This commit is contained in:
Ahmed Bougacha 2017-02-11 01:53:04 +00:00
parent fc979dc9dd
commit 8425f453ef
2 changed files with 33 additions and 1 deletions
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3
llvm/lib/Target/ARM/ARMTargetTransformInfo.cpp
View File

@ -533,7 +533,8 @@ int ARMTTIImpl::getInterleavedMemoryOpCost(unsigned Opcode, Type *VecTy,
unsigned SubVecSize = DL.getTypeSizeInBits(SubVecTy);
// vldN/vstN only support legal vector types of size 64 or 128 in bits.
if (NumElts % Factor == 0 && (SubVecSize == 64 || SubVecSize == 128))
if (NumElts % Factor == 0 && (SubVecSize == 64 || SubVecSize == 128) &&
!VecTy->getScalarType()->isHalfTy())
return Factor;
}

31
llvm/test/Transforms/LoopVectorize/ARM/interleaved_cost.ll
View File

@ -99,3 +99,34 @@ for.body:
for.end:
ret void
}
%half.2 = type {half, half}
define void @half_factor_2(%half.2* %data, i64 %n) {
entry:
br label %for.body
; VF_4-LABEL: Checking a loop in "half_factor_2"
; VF_4: Found an estimated cost of 40 for VF 4 For instruction: %tmp2 = load half, half* %tmp0, align 2
; VF_4-NEXT: Found an estimated cost of 0 for VF 4 For instruction: %tmp3 = load half, half* %tmp1, align 2
; VF_4-NEXT: Found an estimated cost of 0 for VF 4 For instruction: store half 0xH0000, half* %tmp0, align 2
; VF_4-NEXT: Found an estimated cost of 40 for VF 4 For instruction: store half 0xH0000, half* %tmp1, align 2
; VF_8-LABEL: Checking a loop in "half_factor_2"
; VF_8: Found an estimated cost of 80 for VF 8 For instruction: %tmp2 = load half, half* %tmp0, align 2
; VF_8-NEXT: Found an estimated cost of 0 for VF 8 For instruction: %tmp3 = load half, half* %tmp1, align 2
; VF_8-NEXT: Found an estimated cost of 0 for VF 8 For instruction: store half 0xH0000, half* %tmp0, align 2
; VF_8-NEXT: Found an estimated cost of 80 for VF 8 For instruction: store half 0xH0000, half* %tmp1, align 2
for.body:
%i = phi i64 [ 0, %entry ], [ %i.next, %for.body ]
%tmp0 = getelementptr inbounds %half.2, %half.2* %data, i64 %i, i32 0
%tmp1 = getelementptr inbounds %half.2, %half.2* %data, i64 %i, i32 1
%tmp2 = load half, half* %tmp0, align 2
%tmp3 = load half, half* %tmp1, align 2
store half 0., half* %tmp0, align 2
store half 0., half* %tmp1, align 2
%i.next = add nuw nsw i64 %i, 1
%cond = icmp slt i64 %i.next, %n
br i1 %cond, label %for.body, label %for.end
for.end:
ret void
}