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

[Chris Lattner]

Changes in directory llvm/lib/Transforms/Scalar:

InstructionCombining.cpp updated: 1.389 -> 1.390
---
Log message:

Before promoting a malloc type, remove dead uses.  This makes instcombine
more effective at promoting these allocations, catching them earlier in the
compile process.


---
Diffs of the changes:  (+20 -0)

 InstructionCombining.cpp |   20 ++++++++++++++++++++
 1 files changed, 20 insertions(+)


Index: llvm/lib/Transforms/Scalar/InstructionCombining.cpp
diff -u llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.389 llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.390
--- llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.389	Mon Oct 24 01:03:58 2005
+++ llvm/lib/Transforms/Scalar/InstructionCombining.cpp	Mon Oct 24 01:22:12 2005
@@ -3769,6 +3769,26 @@
   const PointerType *PTy = dyn_cast<PointerType>(CI.getType());
   if (AI.isArrayAllocation() || !PTy) return 0;
   
+  // Remove any uses of AI that are dead.
+  assert(!CI.use_empty() && "Dead instructions should be removed earlier!");
+  std::vector<Instruction*> DeadUsers;
+  for (Value::use_iterator UI = AI.use_begin(), E = AI.use_end(); UI != E; ) {
+    Instruction *User = cast<Instruction>(*UI++);
+    if (isInstructionTriviallyDead(User)) {
+      while (UI != E && *UI == User)
+        ++UI; // If this instruction uses AI more than once, don't break UI.
+      
+      // Add operands to the worklist.
+      AddUsesToWorkList(*User);
+      ++NumDeadInst;
+      DEBUG(std::cerr << "IC: DCE: " << *User);
+      
+      User->eraseFromParent();
+      removeFromWorkList(User);
+    }
+  }
+  
+  // Finally, if the instruction now has one use, delete it.
   if (!AI.hasOneUse()) return 0;
   
   // Get the type really allocated and the type casted to.