[llvm] r363012 - [MIR-Canon] Fixing non-determinism that was breaking bots (NFC).

[Puyan Lotfi via llvm-commits]

Author: zer0
Date: Mon Jun 10 17:00:25 2019
New Revision: 363012

URL: http://llvm.org/viewvc/llvm-project?rev=363012&view=rev
Log:
[MIR-Canon] Fixing non-determinism that was breaking bots (NFC).

An earlier fix of a subtle iterator invalidation bug had uncovered a
nondeterminism that was present in the MultiUsers bag. Problem was that
MultiUsers was being looked up using pointers.

This patch is an NFC change that numbers each multiuser and processes each in
numbered order. This fixes the test failure on netbsd and will likely fix the
green-dragon bot too.

Modified:
    llvm/trunk/lib/CodeGen/MIRCanonicalizerPass.cpp

Modified: llvm/trunk/lib/CodeGen/MIRCanonicalizerPass.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MIRCanonicalizerPass.cpp?rev=363012&r1=363011&r2=363012&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/MIRCanonicalizerPass.cpp (original)
+++ llvm/trunk/lib/CodeGen/MIRCanonicalizerPass.cpp Mon Jun 10 17:00:25 2019
@@ -180,6 +180,8 @@ static bool rescheduleCanonically(unsign
   }
 
   std::map<MachineInstr *, std::vector<MachineInstr *>> MultiUsers;
+  std::map<unsigned, MachineInstr *> MultiUserLookup;
+  unsigned UseToBringDefCloserToCount = 0;
   std::vector<MachineInstr *> PseudoIdempotentInstructions;
   std::vector<unsigned> PhysRegDefs;
   for (auto *II : Instructions) {
@@ -255,6 +257,7 @@ static bool rescheduleCanonically(unsign
       if (Delta < Distance) {
         Distance = Delta;
         UseToBringDefCloserTo = UseInst;
+        MultiUserLookup[UseToBringDefCloserToCount++] = UseToBringDefCloserTo;
       }
     }
 
@@ -294,11 +297,11 @@ static bool rescheduleCanonically(unsign
   }
 
   // Sort the defs for users of multiple defs lexographically.
-  for (const auto &E : MultiUsers) {
+  for (const auto &E : MultiUserLookup) {
 
     auto UseI =
         std::find_if(MBB->instr_begin(), MBB->instr_end(),
-                     [&](MachineInstr &MI) -> bool { return &MI == E.first; });
+                     [&](MachineInstr &MI) -> bool { return &MI == E.second; });
 
     if (UseI == MBB->instr_end())
       continue;
@@ -306,7 +309,8 @@ static bool rescheduleCanonically(unsign
     LLVM_DEBUG(
         dbgs() << "Rescheduling Multi-Use Instructions Lexographically.";);
     Changed |= rescheduleLexographically(
-        E.second, MBB, [&]() -> MachineBasicBlock::iterator { return UseI; });
+        MultiUsers[E.second], MBB,
+        [&]() -> MachineBasicBlock::iterator { return UseI; });
   }
 
   PseudoIdempotentInstCount = PseudoIdempotentInstructions.size();