commit 9d29cbad32814f31c91cd2464a3c74df412b0aac
author Jakob Stoklund Olesen <stoklund@2pi.dk> Sat Apr 09 02:59:05 2011 +0000
committer Jakob Stoklund Olesen <stoklund@2pi.dk> Sat Apr 09 02:59:05 2011 +0000
tree 9cd941c99a96a7b696293ade458ef59c09e4ab37
parent 5fc25cccff3cdbfd34d08b9c1233f9af1879018c

Precompute interference for neighbor blocks as long as there is no interference.

This doesn't require seeking in the live interval union, so it is very cheap.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129187 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/InterferenceCache.cpp

diff --git a/lib/CodeGen/InterferenceCache.cpp b/lib/CodeGen/InterferenceCache.cpp
index 0aff128..b1014a9 100644
--- a/lib/CodeGen/InterferenceCache.cpp
+++ b/lib/CodeGen/InterferenceCache.cpp
@@ -26,7 +26,7 @@
   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) {
@@ -91,10 +91,6 @@
 }
 
 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 +105,39 @@
     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();
+
+    // 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);
   }
 
-  // No interference in block.
-  if (!BI->First.isValid())
-    return;
-
-  // 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 +152,4 @@
     if (Backup)
       ++I;
   }
-  PrevPos = Stop;
 }