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| author | Justin Lebar <jlebar@google.com> | 2016-02-22 17:50:52 +0000 |
|---|---|---|
| committer | Justin Lebar <jlebar@google.com> | 2016-02-22 17:50:52 +0000 |
| commit | 5b82c9ba31a05ce22a244e8b4ab6a345c9e8aecc (patch) | |
| tree | eff84d8ae07bc46d975704a62f294a750190c714 /llvm/lib/CodeGen/TailDuplication.cpp | |
| parent | 595e8ab22d72283ea2377abfbd6f3ff691391e97 (diff) | |
| download | bcm5719-llvm-5b82c9ba31a05ce22a244e8b4ab6a345c9e8aecc.tar.gz bcm5719-llvm-5b82c9ba31a05ce22a244e8b4ab6a345c9e8aecc.zip | |
Don't tail-duplicate blocks that contain convergent instructions.
Summary:
Convergent instrs shouldn't be made control-dependent on other values,
but this is basically the whole point of tail duplication. So just bail
if we see a convergent instruction.
Reviewers: iteratee
Subscribers: jholewinski, jhen, hfinkel, tra, jingyue, llvm-commits
Differential Revision: http://reviews.llvm.org/D17320
llvm-svn: 261540
Diffstat (limited to 'llvm/lib/CodeGen/TailDuplication.cpp')
| -rw-r--r-- | llvm/lib/CodeGen/TailDuplication.cpp | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/TailDuplication.cpp b/llvm/lib/CodeGen/TailDuplication.cpp index c2c7a1a3d92..da593ce3717 100644 --- a/llvm/lib/CodeGen/TailDuplication.cpp +++ b/llvm/lib/CodeGen/TailDuplication.cpp @@ -590,6 +590,11 @@ TailDuplicatePass::shouldTailDuplicate(const MachineFunction &MF, if (MI.isNotDuplicable()) return false; + // Convergent instructions can be duplicated only if doing so doesn't add + // new control dependencies, which is what we're going to do here. + if (MI.isConvergent()) + return false; + // Do not duplicate 'return' instructions if this is a pre-regalloc run. // A return may expand into a lot more instructions (e.g. reload of callee // saved registers) after PEI. |
