Use gcc-mp-4.4 to build TSan on Mac....

scripts/build-tsan-for-chromium.sh

 #!/bin/sh
 
 # Copyright (c) 2009-2010 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # Script to build ThreadSanitizer binaries for use with chromium
 source common.sh
 
 POST_BUILD_HOOK_DEFINED=yes
@@ skipping 39 matching lines @@
 
 cd "$VG_TSAN_DIR"
 
 # Apply TSan-specific patches except:
 # * limits (buggy on Mac)
 # * guest_amd64_toIR (already applied in common.sh).
 rm "$THISDIR"/tsan/valgrind_patches/{limits,guest_amd64_toIR}.patch
 for P in "$THISDIR"/tsan/valgrind_patches/*.patch
 do
   patch -p0 -i $P
-  echo
 done
 
+if [ `uname -s` == "Darwin" ]
+then
+  if ls /opt/local/bin/ | grep "^gcc-mp-4\.4" >/dev/null
+  then
+    export GCC_BINARY_MASK="/opt/local/bin/XXX-mp-4.4"
+    export PATH="$THISDIR/macports-gcc-wrapper:$PATH"
+    echo "Using gcc-4.4 from MacPorts to build ThreadSanitizer."
+  elif gcc --version | grep " 4\.[0-3]\.[0-9]\| 3\.[0-9]\.[0-9]" >/dev/null
+  then
+    echo "Your gcc version is older than 4.4."
+    echo "It is recommended to use gcc-4.4 from MacPorts for building"
+    echo "ThreadSanitizer, especially if you plan to commit binaries into SVN."
+    echo "See http://gcc44.darwinports.com/ for getting gcc-4.4"
+    echo ""
+    echo -n "Do you want to continue using old gcc? (y/N)"
+    read CONFIRMATION
+    if [ "$CONFIRMATION" != "y" ]
+    then
+      exit 1
+    fi
+  fi
+fi
+
 # Ugly hack!
 # We build Valrgind binaries in the $VG_TSAN_DIR/out and then pack
 # them into self-contained .sh file into $ORIG_BINARIES_DIR/$PLATFORM
 ORIG_BINARIES_DIR=$BINARIES_DIR
 BINARIES_DIR="$VG_TSAN_DIR/out"
 build_valgrind_for_available_platforms