diff options
Diffstat (limited to 'lib/CodeGen/ExecutionDepsFix.cpp')
-rw-r--r-- | lib/CodeGen/ExecutionDepsFix.cpp | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/lib/CodeGen/ExecutionDepsFix.cpp b/lib/CodeGen/ExecutionDepsFix.cpp index d094411116..050edce2ec 100644 --- a/lib/CodeGen/ExecutionDepsFix.cpp +++ b/lib/CodeGen/ExecutionDepsFix.cpp @@ -471,11 +471,34 @@ void ExeDepsFix::processDefs(MachineInstr *MI, bool Kill) { DEBUG(dbgs() << TRI->getName(RC->getRegister(rx)) << ":\t" << CurInstr << '\t' << *MI); + // How many instructions since rx was last written? + unsigned Clearance = CurInstr - LiveRegs[rx].Def; LiveRegs[rx].Def = CurInstr; // Kill off domains redefined by generic instructions. if (Kill) kill(rx); + + // Verify clearance before partial register updates. + unsigned Pref = TII->getPartialRegUpdateClearance(MI, i, TRI); + if (!Pref) + continue; + DEBUG(dbgs() << "Clearance: " << Clearance << ", want " << Pref); + if (Pref > Clearance) { + DEBUG(dbgs() << ": Break dependency.\n"); + TII->breakPartialRegDependency(MI, i, TRI); + continue; + } + + // The current clearance seems OK, but we may be ignoring a def from a + // back-edge. + if (!SeenUnknownBackEdge || Pref <= unsigned(CurInstr)) { + DEBUG(dbgs() << ": OK.\n"); + continue; + } + + // A def from an unprocessed back-edge may make us break this dependency. + DEBUG(dbgs() << ": Wait for back-edge to resolve.\n"); } ++CurInstr; @@ -663,6 +686,10 @@ bool ExeDepsFix::runOnMachineFunction(MachineFunction &mf) { for (unsigned i = 0, e = Loops.size(); i != e; ++i) { MachineBasicBlock *MBB = Loops[i]; enterBasicBlock(MBB); + for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end(); I != E; + ++I) + if (!I->isDebugValue()) + processDefs(I, false); leaveBasicBlock(MBB); } |