Author: lattner
Date: Fri Aug 10 02:02:50 2007
New Revision: 40984
URL: http://llvm.org/viewvc/llvm-project?rev=40984&view=rev
Log:
memcpy with zero length is hugely expensive, so avoid it. This speeds up
coallescing from 1.17s to 0.88s on siod.
Modified:
llvm/trunk/include/llvm/ADT/SmallVector.h
Modified: llvm/trunk/include/llvm/ADT/SmallVector.h
URL:
http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/ADT/SmallVector.h?rev=40984&r1=40983&r2=40984&view=diff
==============================================================================
--- llvm/trunk/include/llvm/ADT/SmallVector.h (original)
+++ llvm/trunk/include/llvm/ADT/SmallVector.h Fri Aug 10 02:02:50 2007
@@ -380,7 +380,11 @@
unsigned CurSize = unsigned(size());
if (CurSize >= RHSSize) {
// Assign common elements.
- iterator NewEnd = std::copy(RHS.Begin, RHS.Begin+RHSSize, Begin);
+ iterator NewEnd;
+ if (RHSSize)
+ NewEnd = std::copy(RHS.Begin, RHS.Begin+RHSSize, Begin);
+ else
+ NewEnd = Begin;
// Destroy excess elements.
destroy_range(NewEnd, End);
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