[llvm-commits] CVS: llvm/lib/Transforms/Scalar/InstructionCombining.cpp

[Chris Lattner]

Changes in directory llvm/lib/Transforms/Scalar:

InstructionCombining.cpp updated: 1.196 -> 1.197

---
Log message:

Make sure to reprocess instructions used by deleted instructions to avoid
missing opportunities for combination.


---
Diffs of the changes:  (+12 -5)

Index: llvm/lib/Transforms/Scalar/InstructionCombining.cpp
diff -u llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.196 llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.197
--- llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.196	Sat May  1 18:19:52 2004
+++ llvm/lib/Transforms/Scalar/InstructionCombining.cpp	Sat May  1 18:27:23 2004
@@ -2997,6 +2997,8 @@
         BasicBlock *InstParent = I->getParent();
         InstParent->getInstList().insert(I, Result);
 
+        // Make sure that we reprocess all operands now that we reduced their
+        // use counts.
         for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
           if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i)))
             WorkList.push_back(OpI);
@@ -3009,14 +3011,19 @@
       } else {
         DEBUG(std::cerr << "IC: MOD = " << *I);
 
-        BasicBlock::iterator II = I;
-
         // If the instruction was modified, it's possible that it is now dead.
         // if so, remove it.
-        if (dceInstruction(II)) {
-          // Instructions may end up in the worklist more than once.  Erase them
-          // all.
+        if (isInstructionTriviallyDead(I)) {
+          // Make sure we process all operands now that we are reducing their
+          // use counts.
+          for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
+            if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i)))
+              WorkList.push_back(OpI);
+          
+          // Instructions may end up in the worklist more than once.  Erase all
+          // occurrances of this instruction.
           removeFromWorkList(I);
+          I->getParent()->getInstList().erase(I);
           Result = 0;
         }
       }