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[x86] Re-order the combines of select in the X86 backend. This doesn't

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change functionality, but makes it more clear that the dynamic case and
the shuffle case don't overlap in any interesting way.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230689 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chandler Carruth 2015-02-26 21:21:36 +00:00
parent 34f88924e1
commit 9b9d0fcfe9
1 changed files with 19 additions and 19 deletions
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38
lib/Target/X86/X86ISelLowering.cpp
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@ -20740,6 +20740,25 @@ static SDValue PerformSELECTCombine(SDNode *N, SelectionDAG &DAG,
}
}
// We should generate an X86ISD::BLENDI from a vselect if its argument
// is a sign_extend_inreg of an any_extend of a BUILD_VECTOR of
// constants. This specific pattern gets generated when we split a
// selector for a 512 bit vector in a machine without AVX512 (but with
// 256-bit vectors), during legalization:
//
// (vselect (sign_extend (any_extend (BUILD_VECTOR)) i1) LHS RHS)
//
// Iff we find this pattern and the build_vectors are built from
// constants, we translate the vselect into a shuffle_vector that we
// know will be matched by LowerVECTOR_SHUFFLEtoBlend.
if ((N->getOpcode() == ISD::VSELECT ||
N->getOpcode() == X86ISD::SHRUNKBLEND) &&
!DCI.isBeforeLegalize()) {
SDValue Shuffle = transformVSELECTtoBlendVECTOR_SHUFFLE(N, DAG, Subtarget);
if (Shuffle.getNode())
return Shuffle;
}
// If we know that this node is legal then we know that it is going to be
// matched by one of the SSE/AVX BLEND instructions. These instructions only
// depend on the highest bit in each word. Try to use SimplifyDemandedBits
@ -20810,25 +20829,6 @@ static SDValue PerformSELECTCombine(SDNode *N, SelectionDAG &DAG,
}
}
// We should generate an X86ISD::BLENDI from a vselect if its argument
// is a sign_extend_inreg of an any_extend of a BUILD_VECTOR of
// constants. This specific pattern gets generated when we split a
// selector for a 512 bit vector in a machine without AVX512 (but with
// 256-bit vectors), during legalization:
//
// (vselect (sign_extend (any_extend (BUILD_VECTOR)) i1) LHS RHS)
//
// Iff we find this pattern and the build_vectors are built from
// constants, we translate the vselect into a shuffle_vector that we
// know will be matched by LowerVECTOR_SHUFFLEtoBlend.
if ((N->getOpcode() == ISD::VSELECT ||
N->getOpcode() == X86ISD::SHRUNKBLEND) &&
!DCI.isBeforeLegalize()) {
SDValue Shuffle = transformVSELECTtoBlendVECTOR_SHUFFLE(N, DAG, Subtarget);
if (Shuffle.getNode())
return Shuffle;
}
return SDValue();
}