[llvm-commits] [llvm] r123517 - /llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp

[Chris Lattner]

Author: lattner
Date: Fri Jan 14 23:50:18 2011
New Revision: 123517

URL: http://llvm.org/viewvc/llvm-project?rev=123517&view=rev
Log:
one more instcombine variant that is needed to work with future changes,
no functionality change currently.

Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp?rev=123517&r1=123516&r2=123517&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp Fri Jan 14 23:50:18 2011
@@ -672,6 +672,15 @@
         Value *NewMul = Builder->CreateMul(A, B);
         return BinaryOperator::CreateAdd(Op0, NewMul);
       }
+      
+      // X - A*Cst -> X + A*-Cst
+      // X - Cst*A -> X + A*-Cst
+      ConstantInt *BCst;
+      if (match(Op1I, m_Mul(m_Value(A), m_ConstantInt(BCst))) ||
+          match(Op1I, m_Mul(m_ConstantInt(BCst), m_Value(A)))) {
+        Value *NewMul = Builder->CreateMul(A, ConstantExpr::getNeg(BCst));
+        return BinaryOperator::CreateAdd(Op0, NewMul);
+      }
     }
   }