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| author | Evan Cheng <evan.cheng@apple.com> | 2010-07-14 01:22:19 +0000 |
|---|---|---|
| committer | Evan Cheng <evan.cheng@apple.com> | 2010-07-14 01:22:19 +0000 |
| commit | db8980903717e1127463f00a34cae9bd29f82a91 (patch) | |
| tree | cb250ca2613d031edc1a7c36bef5a121871e2c90 /lib/CodeGen/MachineLICM.cpp | |
| parent | 9e82bf12a03117bfce78217662d5cf8e74aef357 (diff) | |
| download | llvm-db8980903717e1127463f00a34cae9bd29f82a91.tar.gz llvm-db8980903717e1127463f00a34cae9bd29f82a91.tar.bz2 llvm-db8980903717e1127463f00a34cae9bd29f82a91.tar.xz | |
Teach ProcessImplicitDefs to transform more COPY instructions into IMPLICIT_DEF (and subsequently eliminate them). This allows machine LICM to hoist IMPLICIT_DEF's. PR7620.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@108304 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/CodeGen/MachineLICM.cpp')
| -rw-r--r-- | lib/CodeGen/MachineLICM.cpp | 9 |
1 files changed, 3 insertions, 6 deletions
diff --git a/lib/CodeGen/MachineLICM.cpp b/lib/CodeGen/MachineLICM.cpp index 956d21c0b3..4c054f51f3 100644 --- a/lib/CodeGen/MachineLICM.cpp +++ b/lib/CodeGen/MachineLICM.cpp @@ -497,11 +497,6 @@ void MachineLICM::HoistRegion(MachineDomTreeNode *N) { /// candidate for LICM. e.g. If the instruction is a call, then it's obviously /// not safe to hoist it. bool MachineLICM::IsLICMCandidate(MachineInstr &I) { - // It is not profitable to hoist implicitdefs. FIXME: Why not? what if they - // are an argument to some other otherwise-hoistable instruction? - if (I.isImplicitDef()) - return false; - // Check if it's safe to move the instruction. bool DontMoveAcrossStore = true; if (!I.isSafeToMove(TII, AA, DontMoveAcrossStore)) @@ -717,7 +712,9 @@ MachineLICM::LookForDuplicate(const MachineInstr *MI, bool MachineLICM::EliminateCSE(MachineInstr *MI, DenseMap<unsigned, std::vector<const MachineInstr*> >::iterator &CI) { - if (CI == CSEMap.end()) + // Do not CSE implicit_def so ProcessImplicitDefs can properly propagate + // the undef property onto uses. + if (CI == CSEMap.end() || MI->isImplicitDef()) return false; if (const MachineInstr *Dup = LookForDuplicate(MI, CI->second)) { |