From c38b84d8f108cb3317475744fcb92c41324b4291 Mon Sep 17 00:00:00 2001
From: Johannes Singler <singler@ira.uka.de>
Date: Fri, 19 Sep 2008 11:37:16 +0000
Subject: [PATCH] re PR libstdc++/37470 (parallel/base.h log2 conflicts with
 math.h)

2008-09-19  Johannes Singler  <singler@ira.uka.de>

        PR libstdc++/37470
        * include/parallel/base.h: Rename log2 to __log2.
          (__log2) Avoid infinite loop for n <= 0, return 0.
        * include/parallel/losertree.h: Rename log2 to __log2.
        * include/parallel/multiseq_selection.h: Likewise.
        * include/parallel/random_shuffle.h: Likewise.

From-SVN: r140490
---
 libstdc++-v3/ChangeLog                             | 9 +++++++++
 libstdc++-v3/include/parallel/base.h               | 6 +++---
 libstdc++-v3/include/parallel/losertree.h          | 8 ++++----
 libstdc++-v3/include/parallel/multiseq_selection.h | 4 ++--
 libstdc++-v3/include/parallel/random_shuffle.h     | 6 +++---
 5 files changed, 21 insertions(+), 12 deletions(-)

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index e018ecbd0dc..99340ec117c 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,12 @@
+2008-09-19  Johannes Singler  <singler@ira.uka.de>
+
+        PR libstdc++/37470
+        * include/parallel/base.h: Rename log2 to __log2.
+	  (__log2) Avoid infinite loop for n <= 0, return 0.
+        * include/parallel/losertree.h: Rename log2 to __log2.
+        * include/parallel/multiseq_selection.h: Likewise.
+        * include/parallel/random_shuffle.h: Likewise.
+
 2008-09-18  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	* include/bits/shared_ptr.h (__shared_count<>::
diff --git a/libstdc++-v3/include/parallel/base.h b/libstdc++-v3/include/parallel/base.h
index 45c3327f5af..2a5dc297ec4 100644
--- a/libstdc++-v3/include/parallel/base.h
+++ b/libstdc++-v3/include/parallel/base.h
@@ -105,14 +105,14 @@ namespace __gnu_parallel
 
 /** @brief Calculates the rounded-down logarithm of @c n for base 2.
   *  @param n Argument.
-  *  @return Returns 0 for argument 0.
+  *  @return Returns 0 for any argument <1.
   */
 template<typename Size>
   inline Size
-  log2(Size n)
+  __log2(Size n)
     {
       Size k;
-      for (k = 0; n != 1; n >>= 1)
+      for (k = 0; n > 1; n >>= 1)
         ++k;
       return k;
     }
diff --git a/libstdc++-v3/include/parallel/losertree.h b/libstdc++-v3/include/parallel/losertree.h
index 7e50bb13d50..84d5be7a05d 100644
--- a/libstdc++-v3/include/parallel/losertree.h
+++ b/libstdc++-v3/include/parallel/losertree.h
@@ -105,7 +105,7 @@ public:
     ik = _k;
 
     // Compute log_2{k} for the Loser Tree
-    _M_log_k = log2(ik - 1) + 1;
+    _M_log_k = __log2(ik - 1) + 1;
 
     // Next greater power of 2.
     k = 1 << _M_log_k;
@@ -368,7 +368,7 @@ public:
     ik = _k;
 
     // Next greater power of 2.
-    k = 1 << (log2(ik - 1) + 1);
+    k = 1 << (__log2(ik - 1) + 1);
     offset = k;
     losers = new Loser[k * 2];
     for (unsigned int i = ik - 1; i < k; i++)
@@ -579,7 +579,7 @@ public:
     ik = _k;
 
     // Next greater power of 2.
-    k = 1 << (log2(ik - 1) + 1);
+    k = 1 << (__log2(ik - 1) + 1);
     offset = k;
     // Avoid default-constructing losers[].key
     losers = static_cast<Loser*>(::operator new(2 * k * sizeof(Loser)));
@@ -815,7 +815,7 @@ public:
     ik = _k;
 
     // Next greater power of 2.
-    k = 1 << (log2(ik - 1) + 1);
+    k = 1 << (__log2(ik - 1) + 1);
     offset = k;
     // Avoid default-constructing losers[].key
     losers = new Loser[2 * k];
diff --git a/libstdc++-v3/include/parallel/multiseq_selection.h b/libstdc++-v3/include/parallel/multiseq_selection.h
index ee9214f4a22..79078af996c 100644
--- a/libstdc++-v3/include/parallel/multiseq_selection.h
+++ b/libstdc++-v3/include/parallel/multiseq_selection.h
@@ -183,7 +183,7 @@ namespace __gnu_parallel
 	  nmax = std::max(nmax, ns[i]);
 	}
 
-      r = log2(nmax) + 1;
+      r = __log2(nmax) + 1;
 
       // Pad all lists to this length, at least as long as any ns[i],
       // equality iff nmax = 2^k - 1.
@@ -429,7 +429,7 @@ namespace __gnu_parallel
 	  nmax = std::max(nmax, ns[i]);
 	}
 
-      r = log2(nmax) + 1;
+      r = __log2(nmax) + 1;
 
       // Pad all lists to this length, at least as long as any ns[i],
       // equality iff nmax = 2^k - 1
diff --git a/libstdc++-v3/include/parallel/random_shuffle.h b/libstdc++-v3/include/parallel/random_shuffle.h
index e6ce95d489d..5e875b4fb4a 100644
--- a/libstdc++-v3/include/parallel/random_shuffle.h
+++ b/libstdc++-v3/include/parallel/random_shuffle.h
@@ -249,7 +249,7 @@ template<typename T>
     if (x <= 1)
       return 1;
     else
-      return (T)1 << (log2(x - 1) + 1);
+      return (T)1 << (__log2(x - 1) + 1);
   }
 
 /** @brief Main parallel random shuffle step.
@@ -352,7 +352,7 @@ template<typename RandomAccessIterator, typename RandomNumberGenerator>
             starts = sd.starts = new difference_type[num_threads + 1];
             int bin_cursor = 0;
             sd.num_bins = num_bins;
-            sd.num_bits = log2(num_bins);
+            sd.num_bits = __log2(num_bins);
 
             difference_type chunk_length = n / num_threads,
                             split = n % num_threads, start = 0;
@@ -450,7 +450,7 @@ template<typename RandomAccessIterator, typename RandomNumberGenerator>
       }
 #endif
 
-    int num_bits = log2(num_bins);
+    int num_bits = __log2(num_bins);
 
     if (num_bins > 1)
       {