[DFAPacketizer] Use DFAEmitter. NFC.

Summary:
This is a NFC change that removes the NFA->DFA construction and emission logic from DFAPacketizerEmitter and instead uses the generic DFAEmitter logic. This allows DFAPacketizer to use the Automaton class from Support and remove a bunch of logic there too.

After this patch, DFAPacketizer is mostly logic for grepping Itineraries and collecting functional units, with no state machine logic. This will allow us to modernize by removing the 16-functional-unit limit and supporting non-itinerary functional units. This is all for followup patches.

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D68992

llvm-svn: 375086

1 files changed, 12 insertions, 67 deletions

diff --git a/llvm/lib/CodeGen/DFAPacketizer.cpp b/llvm/lib/CodeGen/DFAPacketizer.cpp
index 500ae68..d31f9f8d 100644
--- a/llvm/lib/CodeGen/DFAPacketizer.cpp
+++ b/llvm/lib/CodeGen/DFAPacketizer.cpp
@@ -72,52 +72,13 @@ static DFAInput getDFAInsnInput(const std::vector<unsigned> &InsnClass) {
 
 // --------------------------------------------------------------------
 
-DFAPacketizer::DFAPacketizer(const InstrItineraryData *I,
-                             const DFAStateInput (*SIT)[2], const unsigned *SET,
-                             const unsigned (*RTT)[2],
-                             const unsigned *RTET)
-    : InstrItins(I), DFAStateInputTable(SIT), DFAStateEntryTable(SET),
-      DFAResourceTransitionTable(RTT), DFAResourceTransitionEntryTable(RTET) {
-  // Make sure DFA types are large enough for the number of terms & resources.
-  static_assert((DFA_MAX_RESTERMS * DFA_MAX_RESOURCES) <=
-                    (8 * sizeof(DFAInput)),
-                "(DFA_MAX_RESTERMS * DFA_MAX_RESOURCES) too big for DFAInput");
-  static_assert(
-      (DFA_MAX_RESTERMS * DFA_MAX_RESOURCES) <= (8 * sizeof(DFAStateInput)),
-      "(DFA_MAX_RESTERMS * DFA_MAX_RESOURCES) too big for DFAStateInput");
-  clearResources();
-}
-
-// Read the DFA transition table and update CachedTable.
-//
-// Format of the transition tables:
-// DFAStateInputTable[][2] = pairs of <Input, Transition> for all valid
-//                           transitions
-// DFAStateEntryTable[i] = Index of the first entry in DFAStateInputTable
-//                         for the ith state
-//
-void DFAPacketizer::ReadTable(unsigned int state) {
-  unsigned ThisStateIdx = DFAStateEntryTable[state];
-  unsigned NextStateIdxInTable = DFAStateEntryTable[state + 1];
-  // Early exit in case CachedTable has already contains this
-  // state's transitions.
-  if (CachedTable.count(UnsignPair(state, DFAStateInputTable[ThisStateIdx][0])))
-    return;
-
-  for (unsigned TransitionIdx = ThisStateIdx;
-       TransitionIdx < NextStateIdxInTable; TransitionIdx++) {
-    auto TransitionPair =
-        UnsignPair(state, DFAStateInputTable[TransitionIdx][0]);
-    CachedTable[TransitionPair] = DFAStateInputTable[TransitionIdx][1];
-
-    if (TrackResources) {
-      unsigned I = DFAResourceTransitionEntryTable[TransitionIdx];
-      unsigned E = DFAResourceTransitionEntryTable[TransitionIdx + 1];
-      CachedResourceTransitions[TransitionPair] = makeArrayRef(
-          &DFAResourceTransitionTable[I], &DFAResourceTransitionTable[E]);
-    }
-  }
-}
+// Make sure DFA types are large enough for the number of terms & resources.
+static_assert((DFA_MAX_RESTERMS * DFA_MAX_RESOURCES) <=
+              (8 * sizeof(DFAInput)),
+              "(DFA_MAX_RESTERMS * DFA_MAX_RESOURCES) too big for DFAInput");
+static_assert(
+    (DFA_MAX_RESTERMS * DFA_MAX_RESOURCES) <= (8 * sizeof(DFAStateInput)),
+    "(DFA_MAX_RESTERMS * DFA_MAX_RESOURCES) too big for DFAStateInput");
 
 // Return the DFAInput for an instruction class.
 DFAInput DFAPacketizer::getInsnInput(unsigned InsnClass) {
@@ -143,9 +104,7 @@ DFAInput DFAPacketizer::getInsnInput(const std::vector<unsigned> &InsnClass) {
 bool DFAPacketizer::canReserveResources(const MCInstrDesc *MID) {
   unsigned InsnClass = MID->getSchedClass();
   DFAInput InsnInput = getInsnInput(InsnClass);
-  UnsignPair StateTrans = UnsignPair(CurrentState, InsnInput);
-  ReadTable(CurrentState);
-  return CachedTable.count(StateTrans) != 0;
+  return A.canAdd(InsnInput);
 }
 
 // Reserve the resources occupied by a MCInstrDesc and change the current
@@ -153,20 +112,7 @@ bool DFAPacketizer::canReserveResources(const MCInstrDesc *MID) {
 void DFAPacketizer::reserveResources(const MCInstrDesc *MID) {
   unsigned InsnClass = MID->getSchedClass();
   DFAInput InsnInput = getInsnInput(InsnClass);
-  UnsignPair StateTrans = UnsignPair(CurrentState, InsnInput);
-  ReadTable(CurrentState);
-
-  if (TrackResources) {
-    DenseMap<unsigned, SmallVector<unsigned, 8>> NewResourceStates;
-    for (const auto &KV : CachedResourceTransitions[StateTrans]) {
-      assert(ResourceStates.count(KV[0]));
-      NewResourceStates[KV[1]] = ResourceStates[KV[0]];
-      NewResourceStates[KV[1]].push_back(KV[1]);
-    }
-    ResourceStates = NewResourceStates;
-  }
-  assert(CachedTable.count(StateTrans) != 0);
-  CurrentState = CachedTable[StateTrans];
+  A.add(InsnInput);
 }
 
 // Check if the resources occupied by a machine instruction are available
@@ -184,10 +130,9 @@ void DFAPacketizer::reserveResources(MachineInstr &MI) {
 }
 
 unsigned DFAPacketizer::getUsedResources(unsigned InstIdx) {
-  assert(TrackResources && "getUsedResources requires resource tracking!");
-  // Assert that there is at least one example of a valid bundle format.
-  assert(!ResourceStates.empty() && "Invalid bundle!");
-  SmallVectorImpl<unsigned> &RS = ResourceStates.begin()->second;
+  ArrayRef<NfaPath> NfaPaths = A.getNfaPaths();
+  assert(!NfaPaths.empty() && "Invalid bundle!");
+  const NfaPath &RS = NfaPaths.front();
 
   // RS stores the cumulative resources used up to and including the I'th
   // instruction. The 0th instruction is the base case.