[llvm] 23d9ca1 - [CodeGen] Remove EvictionTrack (NFC)

[Kazu Hirata via llvm-commits]

Author: Kazu Hirata
Date: 2022-06-13T07:21:29-07:00
New Revision: 23d9ca10ae8a182e8f78814a152066645e0f67f3

URL: https://github.com/llvm/llvm-project/commit/23d9ca10ae8a182e8f78814a152066645e0f67f3
DIFF: https://github.com/llvm/llvm-project/commit/23d9ca10ae8a182e8f78814a152066645e0f67f3.diff

LOG: [CodeGen] Remove EvictionTrack (NFC)

The last of getEvictor use was removed on Jun 5, 2022 in commit
5c06f7168fd1bd589b831cacd5f1cb8a928446fb, which was itself a patch to
remove unused code.

Once we remove getEvictor, EvictionTrack becomes a write-only data
structure.  The data in it won't affect compilation, so the entire
class is essentially dead.

Added: 
    

Modified: 
    llvm/lib/CodeGen/RegAllocGreedy.cpp
    llvm/lib/CodeGen/RegAllocGreedy.h

Removed: 
    


################################################################################
diff  --git a/llvm/lib/CodeGen/RegAllocGreedy.cpp b/llvm/lib/CodeGen/RegAllocGreedy.cpp
index 5f0525ad48e0..031cd7e57857 100644
--- a/llvm/lib/CodeGen/RegAllocGreedy.cpp
+++ b/llvm/lib/CodeGen/RegAllocGreedy.cpp
@@ -479,8 +479,6 @@ void RAGreedy::evictInterference(const LiveInterval &VirtReg,
     if (!VRM->hasPhys(Intf->reg()))
       continue;
 
-    LastEvicted.addEviction(PhysReg, VirtReg.reg(), Intf->reg());
-
     Matrix->unassign(*Intf);
     assert((ExtraInfo->getCascade(Intf->reg()) < Cascade ||
             VirtReg.isSpillable() < Intf->isSpillable()) &&
@@ -2235,8 +2233,6 @@ MCRegister RAGreedy::selectOrSplitImpl(const LiveInterval &VirtReg,
       AllocationOrder::create(VirtReg.reg(), *VRM, RegClassInfo, Matrix);
   if (MCRegister PhysReg =
           tryAssign(VirtReg, Order, NewVRegs, FixedRegisters)) {
-    // If VirtReg got an assignment, the eviction info is no longer relevant.
-    LastEvicted.clearEvicteeInfo(VirtReg.reg());
     // When NewVRegs is not empty, we may have made decisions such as evicting
     // a virtual register, go with the earlier decisions and use the physical
     // register.
@@ -2271,9 +2267,6 @@ MCRegister RAGreedy::selectOrSplitImpl(const LiveInterval &VirtReg,
       // copy-related live-ranges.
       if (Hint && Hint != PhysReg)
         SetOfBrokenHints.insert(&VirtReg);
-      // If VirtReg eviction someone, the eviction info for it as an evictee is
-      // no longer relevant.
-      LastEvicted.clearEvicteeInfo(VirtReg.reg());
       return PhysReg;
     }
 
@@ -2293,11 +2286,8 @@ MCRegister RAGreedy::selectOrSplitImpl(const LiveInterval &VirtReg,
     // Try splitting VirtReg or interferences.
     unsigned NewVRegSizeBefore = NewVRegs.size();
     Register PhysReg = trySplit(VirtReg, Order, NewVRegs, FixedRegisters);
-    if (PhysReg || (NewVRegs.size() - NewVRegSizeBefore)) {
-      // If VirtReg got split, the eviction info is no longer relevant.
-      LastEvicted.clearEvicteeInfo(VirtReg.reg());
+    if (PhysReg || (NewVRegs.size() - NewVRegSizeBefore))
       return PhysReg;
-    }
   }
 
   // If we couldn't allocate a register from spilling, there is probably some
@@ -2545,7 +2535,6 @@ bool RAGreedy::runOnMachineFunction(MachineFunction &mf) {
   IntfCache.init(MF, Matrix->getLiveUnions(), Indexes, LIS, TRI);
   GlobalCand.resize(32);  // This will grow as needed.
   SetOfBrokenHints.clear();
-  LastEvicted.clear();
 
   allocatePhysRegs();
   tryHintsRecoloring();

diff  --git a/llvm/lib/CodeGen/RegAllocGreedy.h b/llvm/lib/CodeGen/RegAllocGreedy.h
index 8bbb091c58af..f1005377fd67 100644
--- a/llvm/lib/CodeGen/RegAllocGreedy.h
+++ b/llvm/lib/CodeGen/RegAllocGreedy.h
@@ -203,57 +203,6 @@ class LLVM_LIBRARY_VISIBILITY RAGreedy : public MachineFunctionPass,
   static const char *const StageName[];
 #endif
 
-  /// EvictionTrack - Keeps track of past evictions in order to optimize region
-  /// split decision.
-  class EvictionTrack {
-
-  public:
-    using EvictorInfo =
-        std::pair<Register /* evictor */, MCRegister /* physreg */>;
-    using EvicteeInfo = llvm::DenseMap<Register /* evictee */, EvictorInfo>;
-
-  private:
-    /// Each Vreg that has been evicted in the last stage of selectOrSplit will
-    /// be mapped to the evictor Vreg and the PhysReg it was evicted from.
-    EvicteeInfo Evictees;
-
-  public:
-    /// Clear all eviction information.
-    void clear() { Evictees.clear(); }
-
-    ///  Clear eviction information for the given evictee Vreg.
-    /// E.g. when Vreg get's a new allocation, the old eviction info is no
-    /// longer relevant.
-    /// \param Evictee The evictee Vreg for whom we want to clear collected
-    /// eviction info.
-    void clearEvicteeInfo(Register Evictee) { Evictees.erase(Evictee); }
-
-    /// Track new eviction.
-    /// The Evictor vreg has evicted the Evictee vreg from Physreg.
-    /// \param PhysReg The physical register Evictee was evicted from.
-    /// \param Evictor The evictor Vreg that evicted Evictee.
-    /// \param Evictee The evictee Vreg.
-    void addEviction(MCRegister PhysReg, Register Evictor, Register Evictee) {
-      Evictees[Evictee].first = Evictor;
-      Evictees[Evictee].second = PhysReg;
-    }
-
-    /// Return the Evictor Vreg which evicted Evictee Vreg from PhysReg.
-    /// \param Evictee The evictee vreg.
-    /// \return The Evictor vreg which evicted Evictee vreg from PhysReg. 0 if
-    /// nobody has evicted Evictee from PhysReg.
-    EvictorInfo getEvictor(Register Evictee) {
-      if (Evictees.count(Evictee)) {
-        return Evictees[Evictee];
-      }
-
-      return EvictorInfo(0, 0);
-    }
-  };
-
-  // Keeps track of past evictions in order to optimize region split decision.
-  EvictionTrack LastEvicted;
-
   // splitting state.
   std::unique_ptr<SplitAnalysis> SA;
   std::unique_ptr<SplitEditor> SE;