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Fix a bug in algebraic simplification pass.

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In the dot contracting dimensions reorder optimization, check if
the reshape op squishes consecutive dimensions, and bail out if it
is not the case.
This commit is contained in:
Bin Fan 2019-05-09 21:56:00 -07:00
parent 8a8a109e56
commit a4778b0138
2 changed files with 11 additions and 3 deletions
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10
tensorflow/compiler/xla/service/algebraic_simplifier.cc
View File

@ -1581,6 +1581,15 @@ AlgebraicSimplifierVisitor::OptimizeDotOfReorderContractingDims(
lhs_contracting_dims.Add(i);
}
}
// We require the "unsquished" lhs contracting dims to be consecutive.
auto is_iota = [](absl::Span<const int64> dims) {
return absl::c_adjacent_find(dims, [](const int64 a, const int64 b) {
return (b != a + 1);
}) == dims.end();
};
if (!is_iota(AsInt64Slice(lhs_contracting_dims))) {
return nullptr;
}
lhs = lhs->mutable_operand(0);
// Check that the transpose only permutes the contracting dims.
@ -1597,6 +1606,7 @@ AlgebraicSimplifierVisitor::OptimizeDotOfReorderContractingDims(
for (auto dim : lhs_contracting_dims) {
permutation.push_back(transpose_dims[dim] - lhs_contracting_dims[0]);
}
CHECK(IsPermutation(permutation, permutation.size()));
auto new_lhs_contracting_dims =
ComposePermutations(AsInt64Slice(lhs_contracting_dims), permutation);
lhs_contracting_dims.Clear();

4
tensorflow/compiler/xla/service/algebraic_simplifier_test.cc
View File

@ -5372,10 +5372,8 @@ TEST_F(AlgebraicSimplifierTest, DotContractingReorder_SizeOneDims) {
EXPECT_THAT(transpose->dimensions(), ElementsAre(0, 2, 1, 3));
}
// This test exposes a real bug: It tries to read an out-of-bounds array index
// from within ComposePermutations(). TODO(b/132330723): Fix this.
TEST_F(AlgebraicSimplifierTest,
DISABLED_DotContractingReorder_NoChangeInContractingDimsOrder) {
DotContractingReorder_NoChangeInContractingDimsOrder) {
// No optimization opportunity here because the transpose does not reorder the
// contracting dims.
const char* kModuleStr = R"(