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| author | Benjamin Kramer <benny.kra@googlemail.com> | 2012-08-11 19:05:13 +0000 |
|---|---|---|
| committer | Benjamin Kramer <benny.kra@googlemail.com> | 2012-08-11 19:05:13 +0000 |
| commit | ef6494f24dcc01be9db78c827bdc320e672a510f (patch) | |
| tree | ddab413a8b7b9bbdc3c95eff8650c2c7ea5aa697 /llvm/lib/CodeGen/MachineCSE.cpp | |
| parent | 490c45c06c59c386cd72d9e32c048e7367b1d49b (diff) | |
| download | llvm-ef6494f24dcc01be9db78c827bdc320e672a510f.zip llvm-ef6494f24dcc01be9db78c827bdc320e672a510f.tar.gz llvm-ef6494f24dcc01be9db78c827bdc320e672a510f.tar.bz2 | |
PR13578: Teach MachineCSE that instructions that use a constant register can be CSE'd safely.
This is common e.g. when doing rip-relative addressing on x86_64.
llvm-svn: 161728
Diffstat (limited to 'llvm/lib/CodeGen/MachineCSE.cpp')
| -rw-r--r-- | llvm/lib/CodeGen/MachineCSE.cpp | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/llvm/lib/CodeGen/MachineCSE.cpp b/llvm/lib/CodeGen/MachineCSE.cpp index 5153abb..993975e 100644 --- a/llvm/lib/CodeGen/MachineCSE.cpp +++ b/llvm/lib/CodeGen/MachineCSE.cpp @@ -215,8 +215,11 @@ bool MachineCSE::hasLivePhysRegDefUses(const MachineInstr *MI, if (MO.isDef() && (MO.isDead() || isPhysDefTriviallyDead(Reg, I, MBB->end()))) continue; - for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI) - PhysRefs.insert(*AI); + for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI) { + // Reading constant physregs is ok. + if (!MRI->isConstantPhysReg(*AI, *MBB->getParent())) + PhysRefs.insert(*AI); + } if (MO.isDef()) PhysDefs.push_back(Reg); } |