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Teach VMCore to constant fold shufflevectors with constant operands.

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This allows us to compile:

#include <emmintrin.h>
typedef __m128i VSInt16;
typedef short vSInt16 __attribute__ ((__vector_size__ (16)));
VSInt16 t3() {
  return (VSInt16)((vSInt16)_mm_set1_epi16(6518));
}

into:

_t3:
	movaps	LCPI1_0, %xmm0
	ret

instead of:
_t3:
	movl	$6518, %eax
	movd	%eax, %xmm0
	pextrw	$0, %xmm0, %eax
	xorps	%xmm0, %xmm0
	pinsrw	$0, %eax, %xmm0
	punpcklwd	%xmm0, %xmm0
	pshufd	$0, %xmm0, %xmm0
	ret



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@44856 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2007-12-11 07:49:37 +00:00
parent 1afab9c1e0
commit 7431c2ba79
1 changed files with 45 additions and 2 deletions
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47
lib/VMCore/ConstantFold.cpp
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@ -396,11 +396,54 @@ Constant *llvm::ConstantFoldInsertElementInstruction(const Constant *Val,
return 0;
}
/// GetVectorElement - If C is a ConstantVector, ConstantAggregateZero or Undef
/// return the specified element value. Otherwise return null.
static Constant *GetVectorElement(const Constant *C, unsigned EltNo) {
if (const ConstantVector *CV = dyn_cast<ConstantVector>(C))
return const_cast<Constant*>(CV->getOperand(EltNo));
const Type *EltTy = cast<VectorType>(C->getType())->getElementType();
if (isa<ConstantAggregateZero>(C))
return Constant::getNullValue(EltTy);
if (isa<UndefValue>(C))
return UndefValue::get(EltTy);
return 0;
}
Constant *llvm::ConstantFoldShuffleVectorInstruction(const Constant *V1,
const Constant *V2,
const Constant *Mask) {
// TODO:
return 0;
// Undefined shuffle mask -> undefined value.
if (isa<UndefValue>(Mask)) return UndefValue::get(V1->getType());
unsigned NumElts = cast<VectorType>(V1->getType())->getNumElements();
const Type *EltTy = cast<VectorType>(V1->getType())->getElementType();
// Loop over the shuffle mask, evaluating each element.
SmallVector<Constant*, 32> Result;
for (unsigned i = 0; i != NumElts; ++i) {
Constant *InElt = GetVectorElement(Mask, i);
if (InElt == 0) return 0;
if (isa<UndefValue>(InElt))
InElt = UndefValue::get(EltTy);
else if (ConstantInt *CI = dyn_cast<ConstantInt>(InElt)) {
unsigned Elt = CI->getZExtValue();
if (Elt >= NumElts*2)
InElt = UndefValue::get(EltTy);
else if (Elt >= NumElts)
InElt = GetVectorElement(V2, Elt-NumElts);
else
InElt = GetVectorElement(V1, Elt);
if (InElt == 0) return 0;
} else {
// Unknown value.
return 0;
}
Result.push_back(InElt);
}
return ConstantVector::get(&Result[0], Result.size());
}
/// EvalVectorOp - Given two vector constants and a function pointer, apply the