From: Jakob Stoklund Olesen <stoklund@2pi.dk>
Date: Sun, 28 Nov 2010 22:17:14 +0000 (+0000)
Subject: Don't use std::copy and std::copy_backward, run 10% faster.
X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=08d55342e337fd4e80a68b81b8b0cbb100ea0a23;p=oota-llvm.git

Don't use std::copy and std::copy_backward, run 10% faster.

Sometimes std::copy can become a memmove call, and that is not a good idea when
copying relatively few bytes as we are doing. We also get a small win by
changing two loops into one.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@120265 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/include/llvm/ADT/IntervalMap.h b/include/llvm/ADT/IntervalMap.h
index d0a3b53087d..b0a0a0ba9a2 100644
--- a/include/llvm/ADT/IntervalMap.h
+++ b/include/llvm/ADT/IntervalMap.h
@@ -103,7 +103,6 @@
 #include "llvm/ADT/PointerIntPair.h"
 #include "llvm/Support/Allocator.h"
 #include "llvm/Support/RecyclingAllocator.h"
-#include <limits>
 #include <iterator>
 
 // FIXME: Remove debugging code.
@@ -211,8 +210,10 @@ public:
             unsigned j, unsigned Count) {
     assert(i + Count <= M && "Invalid source range");
     assert(j + Count <= N && "Invalid dest range");
-    std::copy(Other.first + i, Other.first + i + Count, first + j);
-    std::copy(Other.second + i, Other.second + i + Count, second + j);
+    for (unsigned e = i + Count; i != e; ++i, ++j) {
+      first[j]  = Other.first[i];
+      second[j] = Other.second[i];
+    }
   }
 
   /// moveLeft - Move elements to the left.
@@ -231,8 +232,10 @@ public:
   void moveRight(unsigned i, unsigned j, unsigned Count) {
     assert(i <= j && "Use moveLeft shift elements left");
     assert(j + Count <= N && "Invalid range");
-    std::copy_backward(first + i, first + i + Count, first + j + Count);
-    std::copy_backward(second + i, second + i + Count, second + j + Count);
+    while (Count--) {
+      first[j + Count]  = first[i + Count];
+      second[j + Count] = second[i + Count];
+    }
   }
 
   /// erase - Erase elements [i;j).