[llvm] r354439 - [RegAllocGreedy] Take last chance recoloring into account in split and assign

[Mikael Holmen via llvm-commits]

Author: uabelho
Date: Tue Feb 19 23:14:39 2019
New Revision: 354439

URL: http://llvm.org/viewvc/llvm-project?rev=354439&view=rev
Log:
[RegAllocGreedy] Take last chance recoloring into account in split and assign

Summary:
This is a follow-up to r353988 where tryEvict was extended to take last
chance recoloring into account. Now we do the same thing for trySplit and
tryAssign.

Now we always pass a "FixedRegisters" argument to canEvictInterference and
tryEvict so it doesn't need to have a default value anymore.

The need for this was found long ago in an out-of-tree target.
Unfortunately I don't have a reproducer for an in-tree target.

Reviewers: qcolombet, rudkx

Reviewed By: qcolombet, rudkx

Subscribers: rudkx, MatzeB, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D58376

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

Modified: llvm/trunk/lib/CodeGen/RegAllocGreedy.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/RegAllocGreedy.cpp?rev=354439&r1=354438&r2=354439&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/RegAllocGreedy.cpp (original)
+++ llvm/trunk/lib/CodeGen/RegAllocGreedy.cpp Tue Feb 19 23:14:39 2019
@@ -465,7 +465,7 @@ private:
   unsigned canReassign(LiveInterval &VirtReg, unsigned PrevReg);
   bool shouldEvict(LiveInterval &A, bool, LiveInterval &B, bool);
   bool canEvictInterference(LiveInterval&, unsigned, bool, EvictionCost&,
-                            const SmallVirtRegSet& = SmallVirtRegSet());
+                            const SmallVirtRegSet&);
   bool canEvictInterferenceInRange(LiveInterval &VirtReg, unsigned PhysReg,
                                    SlotIndex Start, SlotIndex End,
                                    EvictionCost &MaxCost);
@@ -479,10 +479,11 @@ private:
                                   const SmallVirtRegSet &FixedRegisters);
 
   unsigned tryAssign(LiveInterval&, AllocationOrder&,
-                     SmallVectorImpl<unsigned>&);
+                     SmallVectorImpl<unsigned>&,
+                     const SmallVirtRegSet&);
   unsigned tryEvict(LiveInterval&, AllocationOrder&,
-                    SmallVectorImpl<unsigned>&, unsigned = ~0u,
-                    const SmallVirtRegSet& = SmallVirtRegSet());
+                    SmallVectorImpl<unsigned>&, unsigned,
+                    const SmallVirtRegSet&);
   unsigned tryRegionSplit(LiveInterval&, AllocationOrder&,
                           SmallVectorImpl<unsigned>&);
   unsigned isSplitBenefitWorthCost(LiveInterval &VirtReg);
@@ -509,7 +510,8 @@ private:
   unsigned tryLocalSplit(LiveInterval&, AllocationOrder&,
     SmallVectorImpl<unsigned>&);
   unsigned trySplit(LiveInterval&, AllocationOrder&,
-                    SmallVectorImpl<unsigned>&);
+                    SmallVectorImpl<unsigned>&,
+                    const SmallVirtRegSet&);
   unsigned tryLastChanceRecoloring(LiveInterval &, AllocationOrder &,
                                    SmallVectorImpl<unsigned> &,
                                    SmallVirtRegSet &, unsigned);
@@ -759,7 +761,8 @@ LiveInterval *RAGreedy::dequeue(PQueue &
 /// tryAssign - Try to assign VirtReg to an available register.
 unsigned RAGreedy::tryAssign(LiveInterval &VirtReg,
                              AllocationOrder &Order,
-                             SmallVectorImpl<unsigned> &NewVRegs) {
+                             SmallVectorImpl<unsigned> &NewVRegs,
+                             const SmallVirtRegSet &FixedRegisters) {
   Order.rewind();
   unsigned PhysReg;
   while ((PhysReg = Order.next()))
@@ -777,7 +780,7 @@ unsigned RAGreedy::tryAssign(LiveInterva
       LLVM_DEBUG(dbgs() << "missed hint " << printReg(Hint, TRI) << '\n');
       EvictionCost MaxCost;
       MaxCost.setBrokenHints(1);
-      if (canEvictInterference(VirtReg, Hint, true, MaxCost)) {
+      if (canEvictInterference(VirtReg, Hint, true, MaxCost, FixedRegisters)) {
         evictInterference(VirtReg, Hint, NewVRegs);
         return Hint;
       }
@@ -795,7 +798,7 @@ unsigned RAGreedy::tryAssign(LiveInterva
 
   LLVM_DEBUG(dbgs() << printReg(PhysReg, TRI) << " is available at cost "
                     << Cost << '\n');
-  unsigned CheapReg = tryEvict(VirtReg, Order, NewVRegs, Cost);
+  unsigned CheapReg = tryEvict(VirtReg, Order, NewVRegs, Cost, FixedRegisters);
   return CheapReg ? CheapReg : PhysReg;
 }
 
@@ -2455,7 +2458,8 @@ unsigned RAGreedy::tryLocalSplit(LiveInt
 /// assignable.
 /// @return Physreg when VirtReg may be assigned and/or new NewVRegs.
 unsigned RAGreedy::trySplit(LiveInterval &VirtReg, AllocationOrder &Order,
-                            SmallVectorImpl<unsigned>&NewVRegs) {
+                            SmallVectorImpl<unsigned>&NewVRegs,
+                            const SmallVirtRegSet &FixedRegisters) {
   // Ranges must be Split2 or less.
   if (getStage(VirtReg) >= RS_Spill)
     return 0;
@@ -2483,7 +2487,7 @@ unsigned RAGreedy::trySplit(LiveInterval
   if (SA->didRepairRange()) {
     // VirtReg has changed, so all cached queries are invalid.
     Matrix->invalidateVirtRegs();
-    if (unsigned PhysReg = tryAssign(VirtReg, Order, NewVRegs))
+    if (unsigned PhysReg = tryAssign(VirtReg, Order, NewVRegs, FixedRegisters))
       return PhysReg;
   }
 
@@ -3034,7 +3038,7 @@ unsigned RAGreedy::selectOrSplitImpl(Liv
   unsigned CostPerUseLimit = ~0u;
   // First try assigning a free register.
   AllocationOrder Order(VirtReg.reg, *VRM, RegClassInfo, Matrix);
-  if (unsigned PhysReg = tryAssign(VirtReg, Order, NewVRegs)) {
+  if (unsigned PhysReg = tryAssign(VirtReg, Order, NewVRegs, FixedRegisters)) {
     // If VirtReg got an assignment, the eviction info is no longre relevant.
     LastEvicted.clearEvicteeInfo(VirtReg.reg);
     // When NewVRegs is not empty, we may have made decisions such as evicting
@@ -3092,7 +3096,7 @@ unsigned RAGreedy::selectOrSplitImpl(Liv
   if (Stage < RS_Spill) {
     // Try splitting VirtReg or interferences.
     unsigned NewVRegSizeBefore = NewVRegs.size();
-    unsigned PhysReg = trySplit(VirtReg, Order, NewVRegs);
+    unsigned PhysReg = trySplit(VirtReg, Order, NewVRegs, FixedRegisters);
     if (PhysReg || (NewVRegs.size() - NewVRegSizeBefore)) {
       // If VirtReg got split, the eviction info is no longre relevant.
       LastEvicted.clearEvicteeInfo(VirtReg.reg);