diff options
| -rw-r--r-- | lib/CodeGen/MachineLICM.cpp | 13 |
1 files changed, 3 insertions, 10 deletions
diff --git a/lib/CodeGen/MachineLICM.cpp b/lib/CodeGen/MachineLICM.cpp index 200ca0bfbc..f0387d0c04 100644 --- a/lib/CodeGen/MachineLICM.cpp +++ b/lib/CodeGen/MachineLICM.cpp @@ -249,8 +249,8 @@ void MachineLICM::HoistRegion(MachineDomTreeNode *N) { /// IsLoopInvariantInst - Returns true if the instruction is loop /// invariant. I.e., all virtual register operands are defined outside of the -/// loop, physical registers aren't accessed (explicitly or implicitly), and the -/// instruction is hoistable. +/// loop, physical registers aren't accessed explicitly, and there are no side +/// effects that aren't captured by the operands or other flags. /// bool MachineLICM::IsLoopInvariantInst(MachineInstr &I) { DEBUG({ @@ -281,13 +281,6 @@ bool MachineLICM::IsLoopInvariantInst(MachineInstr &I) { DOUT << " * Instruction has side effects.\n"; }); -#if 0 - // FIXME: Don't hoist if this instruction implicitly reads physical registers. - if (I.getInstrDescriptor()->ImplicitUses || - I.getInstrDescriptor()->ImplicitDefs) - return false; -#endif - // The instruction is loop invariant if all of its operands are loop-invariant for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i) { const MachineOperand &MO = I.getOperand(i); @@ -309,7 +302,7 @@ bool MachineLICM::IsLoopInvariantInst(MachineInstr &I) { return false; } - // Don't hoist something that has side effects. + // Don't hoist something that has unmodelled side effects. if (TII->hasUnmodelledSideEffects(&I)) return false; // If we got this far, the instruction is loop invariant! |