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

[Chris Lattner]

Changes in directory llvm/lib/Transforms/Scalar:

InstructionCombining.cpp updated: 1.54 -> 1.55

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Log message:

Add cannonicalization of shl X, 1 -> add X, X


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Diffs of the changes:

Index: llvm/lib/Transforms/Scalar/InstructionCombining.cpp
diff -u llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.54 llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.55
--- llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.54	Mon Sep  9 22:50:54 2002
+++ llvm/lib/Transforms/Scalar/InstructionCombining.cpp	Tue Sep 10 18:04:09 2002
@@ -490,10 +490,18 @@
   // a signed value.
   //
   if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op1)) {
-    unsigned TypeBits = Op0->getType()->getPrimitiveSize()*8;
-    if (CUI->getValue() >= TypeBits &&
-        !(Op0->getType()->isSigned() && I.getOpcode() == Instruction::Shr))
-      return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType()));
+    if (I.getOpcode() == Instruction::Shr) {
+      unsigned TypeBits = Op0->getType()->getPrimitiveSize()*8;
+      if (CUI->getValue() >= TypeBits && !(Op0->getType()->isSigned()))
+        return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType()));
+    }
+
+    // Check to see if we are shifting left by 1.  If so, turn it into an add
+    // instruction.
+    if (I.getOpcode() == Instruction::Shl && CUI->equalsInt(1))
+      // Convert 'shl int %X, 2' to 'add int %X, %X'
+      return BinaryOperator::create(Instruction::Add, Op0, Op0, I.getName());
+
   }
   return 0;
 }