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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
View File

@ -13,7 +13,9 @@
//===----------------------------------------------------------------------===// //===----------------------------------------------------------------------===//
#include "InstCombine.h" #include "InstCombine.h"
#include "llvm/Support/PatternMatch.h"
using namespace llvm; using namespace llvm;
using namespace PatternMatch;
/// CheapToScalarize - Return true if the value is cheaper to scalarize than it /// CheapToScalarize - Return true if the value is cheaper to scalarize than it
/// is to leave as a vector operation. isConstant indicates whether we're /// 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); 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. // Otherwise, we don't know.
return 0; return 0;
} }

10
test/Transforms/InstCombine/vec_extract_elt.ll
View File

@ -7,3 +7,13 @@ define i32 @test(float %f) {
ret i32 %tmp19 ret i32 %tmp19
} }
define i64 @test2(i64 %in) {
%vec = insertelement <8 x i64> undef, i64 %in, i32 0
%splat = shufflevector <8 x i64> %vec, <8 x i64> undef, <8 x i32> zeroinitializer
%add = add <8 x i64> %splat, <i64 0, i64 1, i64 2, i64 3, i64 4, i64 5, i64 6, i64 7>
%scl1 = extractelement <8 x i64> %add, i32 0
%scl2 = extractelement <8 x i64> %add, i32 0
%r = add i64 %scl1, %scl2
ret i64 %r
}