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

[Chris Lattner]

Changes in directory llvm/lib/Transforms/Scalar:

InstructionCombining.cpp updated: 1.394 -> 1.395
---
Log message:

Promote cases like cast (malloc sbyte, 100) to int* into 
(malloc [25 x int]) directly without having to convert to 
(malloc [100 x sbyte]) first.


---
Diffs of the changes:  (+22 -1)

 InstructionCombining.cpp |   23 ++++++++++++++++++++++-
 1 files changed, 22 insertions(+), 1 deletion(-)


Index: llvm/lib/Transforms/Scalar/InstructionCombining.cpp
diff -u llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.394 llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.395
--- llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.394	Thu Oct 27 00:53:56 2005
+++ llvm/lib/Transforms/Scalar/InstructionCombining.cpp	Thu Oct 27 01:12:00 2005
@@ -3826,7 +3826,28 @@
       Amt = InsertNewInstBefore(Tmp, AI);
     }
   } else {
-    return 0;
+    // See if we can satisfy the modulus by pulling a scale out of the array
+    // size argument.
+    unsigned ArraySizeScale = 1;
+    Value *NumElements = AI.getOperand(0);
+    
+    if (ConstantUInt *CI = dyn_cast<ConstantUInt>(NumElements)) {
+      ArraySizeScale = CI->getValue();
+      NumElements = ConstantUInt::get(Type::UIntTy, 1);
+    }
+    
+    // If we can now satisfy the modulus, by using a non-1 scale, we really can
+    // do the xform.
+    if ((AllocElTySize*ArraySizeScale) % CastElTySize != 0) return 0;
+
+    Amt = ConstantUInt::get(Type::UIntTy, 
+                            (AllocElTySize*ArraySizeScale)/CastElTySize);
+    if (ConstantUInt *CI = dyn_cast<ConstantUInt>(NumElements))
+      Amt = ConstantExpr::getMul(CI, cast<ConstantUInt>(Amt));
+    else {
+      Instruction *Tmp = BinaryOperator::createMul(Amt, NumElements, "tmp");
+      Amt = InsertNewInstBefore(Tmp, AI);
+    }
   }
   
   std::string Name = AI.getName(); AI.setName("");