[llvm-commits] [llvm] r147685 - /llvm/trunk/lib/Target/ARM/ARMConstantIslandPass.cpp

[Jakob Stoklund Olesen]

Author: stoklund
Date: Fri Jan  6 15:40:15 2012
New Revision: 147685

URL: http://llvm.org/viewvc/llvm-project?rev=147685&view=rev
Log:
Abort AdjustBBOffsetsAfter early when possible.

Modified:
    llvm/trunk/lib/Target/ARM/ARMConstantIslandPass.cpp

Modified: llvm/trunk/lib/Target/ARM/ARMConstantIslandPass.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMConstantIslandPass.cpp?rev=147685&r1=147684&r2=147685&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/ARMConstantIslandPass.cpp (original)
+++ llvm/trunk/lib/Target/ARM/ARMConstantIslandPass.cpp Fri Jan  6 15:40:15 2012
@@ -1035,14 +1035,22 @@
 #endif // NDEBUG
 
 void ARMConstantIslands::AdjustBBOffsetsAfter(MachineBasicBlock *BB) {
-  for(unsigned i = BB->getNumber() + 1, e = MF->getNumBlockIDs(); i < e; ++i) {
+  unsigned BBNum = BB->getNumber();
+  for(unsigned i = BBNum + 1, e = MF->getNumBlockIDs(); i < e; ++i) {
     // Get the offset and known bits at the end of the layout predecessor.
     // Include the alignment of the current block.
     unsigned LogAlign = MF->getBlockNumbered(i)->getAlignment();
     unsigned Offset = BBInfo[i - 1].postOffset(LogAlign);
     unsigned KnownBits = BBInfo[i - 1].postKnownBits(LogAlign);
 
-    // This is where block i begins.
+    // This is where block i begins.  Stop if the offset is already correct,
+    // and we have updated 2 blocks.  This is the maximum number of blocks
+    // changed before calling this function.
+    if (i > BBNum + 2 &&
+        BBInfo[i].Offset == Offset &&
+        BBInfo[i].KnownBits == KnownBits)
+      break;
+
     BBInfo[i].Offset = Offset;
     BBInfo[i].KnownBits = KnownBits;
   }