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Teach InstCombine to optimize extract of a value from a vector add operation with a constant zero.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@172576 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nadav Rotem
2013-01-15 23:43:14 +00:00
parent 9ccb76998f
commit 83d5853833
2 changed files with 19 additions and 0 deletions
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9
lib/Transforms/InstCombine/InstCombineVectorOps.cpp
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@ -13,7 +13,9 @@
//===----------------------------------------------------------------------===//
#include "InstCombine.h"
#include "llvm/Support/PatternMatch.h"
using namespace llvm;
using namespace PatternMatch;
/// CheapToScalarize - Return true if the value is cheaper to scalarize than it
/// is to leave as a vector operation. isConstant indicates whether we're
@ -92,6 +94,13 @@ static Value *FindScalarElement(Value *V, unsigned EltNo) {
return FindScalarElement(SVI->getOperand(1), InEl - LHSWidth);
}
// Extract a value from a vector add operation with a constant zero.
Value *Val = 0; Constant *Con = 0;
if (match(V, m_Add(m_Value(Val), m_Constant(Con)))) {
if (Con->getAggregateElement(EltNo)->isNullValue())
return FindScalarElement(Val, EltNo);
}
// Otherwise, we don't know.
return 0;
}