[llvm-commits] [llvm] r72565 - /llvm/trunk/lib/Transforms/Scalar/GVN.cpp

[Torok Edwin]

Author: edwin
Date: Fri May 29 04:46:03 2009
New Revision: 72565

URL: http://llvm.org/viewvc/llvm-project?rev=72565&view=rev
Log:
Add a DEBUG() output to GVN that prints the instruction clobbering a load.
This is useful when trying to figure out why GVN didn't eliminate redundant
loads.

Modified:
    llvm/trunk/lib/Transforms/Scalar/GVN.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/GVN.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/GVN.cpp?rev=72565&r1=72564&r2=72565&view=diff

==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/GVN.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/GVN.cpp Fri May 29 04:46:03 2009
@@ -1158,8 +1158,18 @@
   MemDepResult dep = MD->getDependency(L);
   
   // If the value isn't available, don't do anything!
-  if (dep.isClobber())
+  if (dep.isClobber()) {
+    DEBUG(
+      // fast print dep, using operator<< on instruction would be too slow
+      DOUT << "GVN: load ";
+      WriteAsOperand(*DOUT.stream(), L);
+      Instruction *I = dep.getInst();
+      DOUT << " is clobbered by " << I->getOpcodeName() << " instruction ";
+      WriteAsOperand(*DOUT.stream(), I, false);
+      DOUT << "\n";
+    );
     return false;
+  }
 
   // If it is defined in another block, try harder.
   if (dep.isNonLocal())