Resolve part of a fixme and add a new one.

[oota-llvm.git] / lib / CodeGen / InterferenceCache.cpp

diff --git a/lib/CodeGen/InterferenceCache.cpp b/lib/CodeGen/InterferenceCache.cpp
index 0aff128c16d0416521fa51964d5d1ca1591d68e1..29b47bd67ece2fe68274420bb5aab408b5176091 100644 (file)
--- a/lib/CodeGen/InterferenceCache.cpp
+++ b/lib/CodeGen/InterferenceCache.cpp
@@ -14,19 +14,23 @@
 #define DEBUG_TYPE "regalloc"
 #include "InterferenceCache.h"
 #include "llvm/Target/TargetRegisterInfo.h"
+#include "llvm/Support/ErrorHandling.h"
 
 using namespace llvm;
 
+// Static member used for null interference cursors.
+InterferenceCache::BlockInterference InterferenceCache::Cursor::NoInterference;
+
 void InterferenceCache::init(MachineFunction *mf,
                              LiveIntervalUnion *liuarray,
                              SlotIndexes *indexes,
-                            const TargetRegisterInfo *tri) {
+                             const TargetRegisterInfo *tri) {
   MF = mf;
   LIUArray = liuarray;
   TRI = tri;
   PhysRegEntries.assign(TRI->getNumRegs(), 0);
   for (unsigned i = 0; i != CacheEntries; ++i)
-    Entries[i].clear(indexes);
+    Entries[i].clear(mf, indexes);
 }
 
 InterferenceCache::Entry *InterferenceCache::get(unsigned PhysReg) {
@@ -40,9 +44,18 @@ InterferenceCache::Entry *InterferenceCache::get(unsigned PhysReg) {
   E = RoundRobin;
   if (++RoundRobin == CacheEntries)
     RoundRobin = 0;
-  Entries[E].reset(PhysReg, LIUArray, TRI, MF);
-  PhysRegEntries[PhysReg] = E;
-  return &Entries[E];
+  for (unsigned i = 0; i != CacheEntries; ++i) {
+    // Skip entries that are in use.
+    if (Entries[E].hasRefs()) {
+      if (++E == CacheEntries)
+        E = 0;
+      continue;
+    }
+    Entries[E].reset(PhysReg, LIUArray, TRI, MF);
+    PhysRegEntries[PhysReg] = E;
+    return &Entries[E];
+  }
+  llvm_unreachable("Ran out of interference cache entries.");
 }
 
 /// revalidate - LIU contents have changed, update tags.
@@ -59,6 +72,7 @@ void InterferenceCache::Entry::reset(unsigned physReg,
                                      LiveIntervalUnion *LIUArray,
                                      const TargetRegisterInfo *TRI,
                                      const MachineFunction *MF) {
+  assert(!hasRefs() && "Cannot reset cache entry with references");
   // LIU's changed, invalidate cache.
   ++Tag;
   PhysReg = physReg;
@@ -91,10 +105,6 @@ bool InterferenceCache::Entry::valid(LiveIntervalUnion *LIUArray,
 }
 
 void InterferenceCache::Entry::update(unsigned MBBNum) {
-  BlockInterference *BI = &Blocks[MBBNum];
-  BI->Tag = Tag;
-  BI->First = BI->Last = SlotIndex();
-
   SlotIndex Start, Stop;
   tie(Start, Stop) = Indexes->getMBBRange(MBBNum);
 
@@ -109,23 +119,39 @@ void InterferenceCache::Entry::update(unsigned MBBNum) {
     PrevPos = Start;
   }
 
-  // Check for first interference.
-  for (unsigned i = 0, e = Iters.size(); i != e; ++i) {
-    Iter &I = Iters[i];
-    if (!I.valid())
-      continue;
-    SlotIndex StartI = I.start();
-    if (StartI >= Stop)
-      continue;
-    if (!BI->First.isValid() || StartI < BI->First)
-      BI->First = StartI;
-  }
+  MachineFunction::const_iterator MFI = MF->getBlockNumbered(MBBNum);
+  BlockInterference *BI = &Blocks[MBBNum];
+  for (;;) {
+    BI->Tag = Tag;
+    BI->First = BI->Last = SlotIndex();
 
-  // No interference in block.
-  if (!BI->First.isValid())
-    return;
+    // Check for first interference.
+    for (unsigned i = 0, e = Iters.size(); i != e; ++i) {
+      Iter &I = Iters[i];
+      if (!I.valid())
+        continue;
+      SlotIndex StartI = I.start();
+      if (StartI >= Stop)
+        continue;
+      if (!BI->First.isValid() || StartI < BI->First)
+        BI->First = StartI;
+    }
+
+    PrevPos = Stop;
+    if (BI->First.isValid())
+      break;
+
+    // No interference in this block? Go ahead and precompute the next block.
+    if (++MFI == MF->end())
+      return;
+    MBBNum = MFI->getNumber();
+    BI = &Blocks[MBBNum];
+    if (BI->Tag == Tag)
+      return;
+    tie(Start, Stop) = Indexes->getMBBRange(MBBNum);
+  }
 
-  // Check for last interference.
+  // Check for last interference in block.
   for (unsigned i = 0, e = Iters.size(); i != e; ++i) {
     Iter &I = Iters[i];
     if (!I.valid() || I.start() >= Stop)
@@ -140,5 +166,4 @@ void InterferenceCache::Entry::update(unsigned MBBNum) {
     if (Backup)
       ++I;
   }
-  PrevPos = Stop;
 }