[llvm] r223970 - ConstantFold: Clean up X * undef code

[David Majnemer]

Author: majnemer
Date: Wed Dec 10 15:58:17 2014
New Revision: 223970

URL: http://llvm.org/viewvc/llvm-project?rev=223970&view=rev
Log:
ConstantFold: Clean up X * undef code

No functional change intended.

Modified:
    llvm/trunk/lib/IR/ConstantFold.cpp

Modified: llvm/trunk/lib/IR/ConstantFold.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/IR/ConstantFold.cpp?rev=223970&r1=223969&r2=223970&view=diff
==============================================================================
--- llvm/trunk/lib/IR/ConstantFold.cpp (original)
+++ llvm/trunk/lib/IR/ConstantFold.cpp Wed Dec 10 15:58:17 2014
@@ -915,12 +915,14 @@ Constant *llvm::ConstantFoldBinaryInstru
         return C1;
       return Constant::getNullValue(C1->getType());   // undef & X -> 0
     case Instruction::Mul: {
-      ConstantInt *CI;
-      // X * undef -> undef   if X is odd or undef
-      if (((CI = dyn_cast<ConstantInt>(C1)) && CI->getValue()[0]) ||
-          ((CI = dyn_cast<ConstantInt>(C2)) && CI->getValue()[0]) ||
-          (isa<UndefValue>(C1) && isa<UndefValue>(C2)))
-        return UndefValue::get(C1->getType());
+      // undef * undef -> undef
+      if (isa<UndefValue>(C1) && isa<UndefValue>(C2))
+        return C1;
+      const APInt *CV;
+      // X * undef -> undef   if X is odd
+      if (match(C1, m_APInt(CV)) || match(C2, m_APInt(CV)))
+        if ((*CV)[0])
+          return UndefValue::get(C1->getType());
 
       // X * undef -> 0       otherwise
       return Constant::getNullValue(C1->getType());