[MIR-Canon] Adding support for multi-def -> user distance reduction.

llvm-svn: 329243

1 files changed, 17 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/MIRCanonicalizerPass.cpp b/llvm/lib/CodeGen/MIRCanonicalizerPass.cpp
index bd939fdf104..9ef097c97e7 100644
--- a/llvm/lib/CodeGen/MIRCanonicalizerPass.cpp
+++ b/llvm/lib/CodeGen/MIRCanonicalizerPass.cpp
@@ -189,6 +189,7 @@ static bool rescheduleCanonically(unsigned &PseudoIdempotentInstCount,
     Instructions.push_back(&MI);
   }
 
+  std::map<MachineInstr *, std::vector<MachineInstr *>> MultiUsers;
   std::vector<MachineInstr *> PseudoIdempotentInstructions;
   std::vector<unsigned> PhysRegDefs;
   for (auto *II : Instructions) {
@@ -297,10 +298,26 @@ static bool rescheduleCanonically(unsigned &PseudoIdempotentInstCount,
       UseI->dump();
     });
 
+    MultiUsers[UseToBringDefCloserTo].push_back(Def);
     Changed = true;
     MBB->splice(UseI, MBB, DefI);
   }
 
+  // Sort the defs for users of multiple defs lexographically.
+  for (const auto &E : MultiUsers) {
+
+    auto UseI =
+        std::find_if(MBB->instr_begin(), MBB->instr_end(),
+                     [&](MachineInstr &MI) -> bool { return &MI == E.first; });
+
+    if (UseI == MBB->instr_end())
+      continue;
+
+    DEBUG(dbgs() << "Rescheduling Multi-Use Instructions Lexographically.";);
+    Changed |= rescheduleLexographically(
+        E.second, MBB, [&]() -> MachineBasicBlock::iterator { return UseI; });
+  }
+
   PseudoIdempotentInstCount = PseudoIdempotentInstructions.size();
   DEBUG(dbgs() << "Rescheduling Idempotent Instructions Lexographically.";);
   Changed |= rescheduleLexographically(