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r249718 | ast | 2015-10-08 11:52:40 -0700 (Thu, 08 Oct 2015) | 16 lines
[bpf] Do not expand UNDEF SDNode during insn selection lowering
o Before this patch, BPF backend will expand UNDEF node
to i64 constant 0.
o For second pass of dag combiner, legalizer will run through
each to-be-processed dag node.
o If any new SDNode is generated and has an undef operand,
dag combiner will put undef node, newly-generated constant-0 node,
and any node which uses these nodes in the working list.
o During this process, it is possible undef operand is
generated again, and this will form an infinite loop
for dag combiner pass2.
o This patch allows UNDEF to be a legal type.
Signed-off-by: Yonghong Song <yhs@plumgrid.com>
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_37@251177 91177308-0d34-0410-b5e6-96231b3b80d8