[llvm-commits] [llvm] r159969 - /llvm/trunk/lib/Analysis/ScalarEvolution.cpp

[Dan Gohman]

Author: djg
Date: Mon Jul  9 18:51:20 2012
New Revision: 159969

URL: http://llvm.org/viewvc/llvm-project?rev=159969&view=rev
Log:
Delete code for folding undefs in ScalarEvolution. It's invalid in
obscure ways, and it isn't actually important in the real world.

Modified:
    llvm/trunk/lib/Analysis/ScalarEvolution.cpp

Modified: llvm/trunk/lib/Analysis/ScalarEvolution.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolution.cpp?rev=159969&r1=159968&r2=159969&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ScalarEvolution.cpp (original)
+++ llvm/trunk/lib/Analysis/ScalarEvolution.cpp Mon Jul  9 18:51:20 2012
@@ -878,13 +878,6 @@
     return getAddRecExpr(Operands, AddRec->getLoop(), SCEV::FlagAnyWrap);
   }
 
-  // As a special case, fold trunc(undef) to undef. We don't want to
-  // know too much about SCEVUnknowns, but this special case is handy
-  // and harmless.
-  if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(Op))
-    if (isa<UndefValue>(U->getValue()))
-      return getSCEV(UndefValue::get(Ty));
-
   // The cast wasn't folded; create an explicit cast node. We can reuse
   // the existing insert position since if we get here, we won't have
   // made any changes which would invalidate it.
@@ -1344,13 +1337,6 @@
     return getAddRecExpr(Ops, AR->getLoop(), SCEV::FlagNW);
   }
 
-  // As a special case, fold anyext(undef) to undef. We don't want to
-  // know too much about SCEVUnknowns, but this special case is handy
-  // and harmless.
-  if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(Op))
-    if (isa<UndefValue>(U->getValue()))
-      return getSCEV(UndefValue::get(Ty));
-
   // If the expression is obviously signed, use the sext cast value.
   if (isa<SCEVSMaxExpr>(Op))
     return SExt;