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Fold a loop for array processing in ComputeLinearIndex

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When processing an array, every Elt has the same layout, it is
useless to recursively call each ComputeLinearIndex on each element.
Just do it once and multiply by the number of elements.
    
Differential Revision: http://reviews.llvm.org/D6832




git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225949 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Mehdi Amini
2015-01-14 05:33:01 +00:00
parent 7f0cbb5703
commit 497b958447
2 changed files with 27 additions and 11 deletions
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21
lib/CodeGen/Analysis.cpp
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@ -30,10 +30,9 @@
using namespace llvm;
/// ComputeLinearIndex - Given an LLVM IR aggregate type and a sequence
/// of insertvalue or extractvalue indices that identify a member, return
/// the linearized index of the start of the member.
///
/// Compute the linearized index of a member in a nested aggregate/struct/array
/// by recursing and accumulating CurIndex as long as there are indices in the
/// index list.
unsigned llvm::ComputeLinearIndex(Type *Ty,
const unsigned *Indices,
const unsigned *IndicesEnd,
@ -57,11 +56,17 @@ unsigned llvm::ComputeLinearIndex(Type *Ty,
// Given an array type, recursively traverse the elements.
else if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
Type *EltTy = ATy->getElementType();
for (unsigned i = 0, e = ATy->getNumElements(); i != e; ++i) {
if (Indices && *Indices == i)
return ComputeLinearIndex(EltTy, Indices+1, IndicesEnd, CurIndex);
CurIndex = ComputeLinearIndex(EltTy, nullptr, nullptr, CurIndex);
unsigned NumElts = ATy->getNumElements();
// Compute the Linear offset when jumping one element of the array
unsigned EltLinearOffset = ComputeLinearIndex(EltTy, nullptr, nullptr, 0);
if (Indices && *Indices < NumElts) {
// If the indice is inside the array, compute the index to the requested
// elt and recurse inside the element with the end of the indices list
CurIndex += EltLinearOffset* *Indices;
return ComputeLinearIndex(EltTy, Indices+1, IndicesEnd, CurIndex);
}
// Out of bound? Assert instead?
CurIndex += EltLinearOffset*NumElts;
return CurIndex;
}
// We haven't found the type we're looking for, so keep searching.