[llvm-commits] [llvm] r150259 - in /llvm/trunk/lib/CodeGen: InterferenceCache.cpp InterferenceCache.h RegAllocGreedy.cpp

[Jakob Stoklund Olesen]

Author: stoklund
Date: Fri Feb 10 12:58:34 2012
New Revision: 150259

URL: http://llvm.org/viewvc/llvm-project?rev=150259&view=rev
Log:
Add register mask support to InterferenceCache.

This makes global live range splitting behave identically with and
without register mask operands.

This is not necessarily the best way of using register masks for live
range splitting.  It would be more efficient to first split global live
ranges around calls (i.e., register masks), and reserve the fine grained
per-physreg interference guidance for global live ranges that do not
cross calls.

For now the goal is to produce identical assembly when enabling register
masks.

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

Modified: llvm/trunk/lib/CodeGen/InterferenceCache.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/InterferenceCache.cpp?rev=150259&r1=150258&r2=150259&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/InterferenceCache.cpp (original)
+++ llvm/trunk/lib/CodeGen/InterferenceCache.cpp Fri Feb 10 12:58:34 2012
@@ -15,6 +15,7 @@
 #include "InterferenceCache.h"
 #include "llvm/Target/TargetRegisterInfo.h"
 #include "llvm/Support/ErrorHandling.h"
+#include "llvm/CodeGen/LiveIntervalAnalysis.h"
 
 using namespace llvm;
 
@@ -24,13 +25,14 @@
 void InterferenceCache::init(MachineFunction *mf,
                              LiveIntervalUnion *liuarray,
                              SlotIndexes *indexes,
+                             LiveIntervals *lis,
                              const TargetRegisterInfo *tri) {
   MF = mf;
   LIUArray = liuarray;
   TRI = tri;
   PhysRegEntries.assign(TRI->getNumRegs(), 0);
   for (unsigned i = 0; i != CacheEntries; ++i)
-    Entries[i].clear(mf, indexes);
+    Entries[i].clear(mf, indexes, lis);
 }
 
 InterferenceCache::Entry *InterferenceCache::get(unsigned PhysReg) {
@@ -104,6 +106,11 @@
   return i == e;
 }
 
+// Test if a register mask clobbers PhysReg.
+static inline bool maskClobber(const uint32_t *Mask, unsigned PhysReg) {
+  return !(Mask[PhysReg/32] & (1u << PhysReg%32));
+}
+
 void InterferenceCache::Entry::update(unsigned MBBNum) {
   SlotIndex Start, Stop;
   tie(Start, Stop) = Indexes->getMBBRange(MBBNum);
@@ -121,6 +128,8 @@
 
   MachineFunction::const_iterator MFI = MF->getBlockNumbered(MBBNum);
   BlockInterference *BI = &Blocks[MBBNum];
+  ArrayRef<SlotIndex> RegMaskSlots;
+  ArrayRef<const uint32_t*> RegMaskBits;
   for (;;) {
     BI->Tag = Tag;
     BI->First = BI->Last = SlotIndex();
@@ -137,6 +146,18 @@
         BI->First = StartI;
     }
 
+    // Also check for register mask interference.
+    RegMaskSlots = LIS->getRegMaskSlotsInBlock(MBBNum);
+    RegMaskBits = LIS->getRegMaskBitsInBlock(MBBNum);
+    SlotIndex Limit = BI->First.isValid() ? BI->First : Stop;
+    for (unsigned i = 0, e = RegMaskSlots.size();
+         i != e && RegMaskSlots[i] < Limit; ++i)
+      if (maskClobber(RegMaskBits[i], PhysReg)) {
+        // Register mask i clobbers PhysReg before the LIU interference.
+        BI->First = RegMaskSlots[i];
+        break;
+      }
+
     PrevPos = Stop;
     if (BI->First.isValid())
       break;
@@ -166,4 +187,14 @@
     if (Backup)
       ++I;
   }
+
+  // Also check for register mask interference.
+  SlotIndex Limit = BI->Last.isValid() ? BI->Last : Start;
+  for (unsigned i = RegMaskSlots.size(); i && RegMaskSlots[i-1] > Limit; --i)
+    if (maskClobber(RegMaskBits[i-1], PhysReg)) {
+      // Register mask i-1 clobbers PhysReg after the LIU interference.
+      // Model the regmask clobber as a dead def.
+      BI->Last = RegMaskSlots[i-1].getDeadSlot();
+      break;
+    }
 }

Modified: llvm/trunk/lib/CodeGen/InterferenceCache.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/InterferenceCache.h?rev=150259&r1=150258&r2=150259&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/InterferenceCache.h (original)
+++ llvm/trunk/lib/CodeGen/InterferenceCache.h Fri Feb 10 12:58:34 2012
@@ -18,6 +18,8 @@
 
 namespace llvm {
 
+class LiveIntervals;
+
 class InterferenceCache {
   const TargetRegisterInfo *TRI;
   LiveIntervalUnion *LIUArray;
@@ -51,6 +53,9 @@
     /// Indexes - Mapping block numbers to SlotIndex ranges.
     SlotIndexes *Indexes;
 
+    /// LIS - Used for accessing register mask interference maps.
+    LiveIntervals *LIS;
+
     /// PrevPos - The previous position the iterators were moved to.
     SlotIndex PrevPos;
 
@@ -70,13 +75,14 @@
     void update(unsigned MBBNum);
 
   public:
-    Entry() : PhysReg(0), Tag(0), RefCount(0), Indexes(0) {}
+    Entry() : PhysReg(0), Tag(0), RefCount(0), Indexes(0), LIS(0) {}
 
-    void clear(MachineFunction *mf, SlotIndexes *indexes) {
+    void clear(MachineFunction *mf, SlotIndexes *indexes, LiveIntervals *lis) {
       assert(!hasRefs() && "Cannot clear cache entry with references");
       PhysReg = 0;
       MF = mf;
       Indexes = indexes;
+      LIS = lis;
     }
 
     unsigned getPhysReg() const { return PhysReg; }
@@ -126,7 +132,7 @@
   InterferenceCache() : TRI(0), LIUArray(0), MF(0), RoundRobin(0) {}
 
   /// init - Prepare cache for a new function.
-  void init(MachineFunction*, LiveIntervalUnion*, SlotIndexes*,
+  void init(MachineFunction*, LiveIntervalUnion*, SlotIndexes*, LiveIntervals*,
             const TargetRegisterInfo *);
 
   /// getMaxCursors - Return the maximum number of concurrent cursors that can

Modified: llvm/trunk/lib/CodeGen/RegAllocGreedy.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/RegAllocGreedy.cpp?rev=150259&r1=150258&r2=150259&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/RegAllocGreedy.cpp (original)
+++ llvm/trunk/lib/CodeGen/RegAllocGreedy.cpp Fri Feb 10 12:58:34 2012
@@ -1644,7 +1644,7 @@
   ExtraRegInfo.clear();
   ExtraRegInfo.resize(MRI->getNumVirtRegs());
   NextCascade = 1;
-  IntfCache.init(MF, &getLiveUnion(0), Indexes, TRI);
+  IntfCache.init(MF, &getLiveUnion(0), Indexes, LIS, TRI);
   GlobalCand.resize(32);  // This will grow as needed.
 
   allocatePhysRegs();