[llvm-commits] [llvm] r106979 - /llvm/trunk/lib/Transforms/Scalar/ScalarReplAggregates.cpp

[Chris Lattner]

Author: lattner
Date: Sun Jun 27 02:58:26 2010
New Revision: 106979

URL: http://llvm.org/viewvc/llvm-project?rev=106979&view=rev
Log:
minor cleanup to SROA: when lowering type unsafe accesses to
large integers, the first inserted value would always create
an 'or X, 0'.  Even though this is trivially zapped by
instcombine, don't bother creating this pointless instruction.

Modified:
    llvm/trunk/lib/Transforms/Scalar/ScalarReplAggregates.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/ScalarReplAggregates.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/ScalarReplAggregates.cpp?rev=106979&r1=106978&r2=106979&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/ScalarReplAggregates.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/ScalarReplAggregates.cpp Sun Jun 27 02:58:26 2010
@@ -1655,7 +1655,12 @@
       SrcField = BinaryOperator::CreateShl(SrcField, ShiftVal, "", LI);
     }
 
-    ResultVal = BinaryOperator::CreateOr(SrcField, ResultVal, "", LI);
+    // Don't create an 'or x, 0' on the first iteration.
+    if (!isa<Constant>(ResultVal) ||
+        !cast<Constant>(ResultVal)->isNullValue())
+      ResultVal = BinaryOperator::CreateOr(SrcField, ResultVal, "", LI);
+    else
+      ResultVal = SrcField;
   }
 
   // Handle tail padding by truncating the result