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[bpf] Do not expand UNDEF SDNode during insn selection lowering
AuditedrL249718

Description

[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>

Details

Auditors
tstellarAMD
llvm-commits
Group Auditors
Restricted Project
Committed
astOct 8 2015, 11:52 AM
Parents
rL249717: Debug trace and assert statement changes for wait/release improvements.
Branches
Unknown
Tags
Unknown

Event Timeline

ast added auditors: Restricted Project, llvm-commits, tstellarAMD.Oct 8 2015, 7:10 PM

bug fix

tstellarAMD added a subscriber: tstellarAMD.

LGTM. Go ahead and merge to the 3.7 branch. Please use the merge.sh script in utils/release so we get a consistent commit message.

tstellarAMD added a project: Restricted Project.Nov 9 2015, 8:39 AM