valgrind.sh vs gdb: keep the registers in gdb in sync with the code.

tools/valgrind/valgrind.sh

 #!/bin/bash
 
 # Copyright (c) 2011 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.
 
 # This is a small script for manually launching valgrind, along with passing
 # it the suppression file, and some helpful arguments (automatically attaching
 # the debugger on failures, etc).  Run it from your repo root, something like:
 #  $ sh ./tools/valgrind/valgrind.sh ./out/Debug/chrome
 #
 # This is mostly intended for running the chrome browser interactively.
 # To run unit tests, you probably want to run chrome_tests.sh instead.
 # That's the script used by the valgrind buildbot.
 
 export THISDIR=`dirname $0`
 
 setup_memcheck() {
   RUN_COMMAND="valgrind"
   # Prefer a 32-bit gdb if it's available.
   GDB="/usr/bin/gdb32";
   if [ ! -x $GDB ]; then
     GDB="gdb"
   fi
 
   # Prompt to attach gdb when there was an error detected.
   DEFAULT_TOOL_FLAGS=("--db-command=$GDB -nw %f %p" "--db-attach=yes" \
+                      # Keep the registers in gdb in sync with the code.
+                      "--vex-iropt-precise-memory-exns=yes" \
                       # Overwrite newly allocated or freed objects
                       # with 0x41 to catch inproper use.
                       "--malloc-fill=41" "--free-fill=41" \
                       # Increase the size of stacks being tracked.
                       "--num-callers=30")
 }
 
 setup_tsan() {
   RUN_COMMAND="valgrind-tsan.sh"
   IGNORE_FILE="$THISDIR/tsan/ignores.txt"
@@ skipping 69 matching lines @@
 G_SLICE=always-malloc \
 NSS_DISABLE_UNLOAD=1 \
 NSS_DISABLE_ARENA_FREE_LIST=1 \
 G_DEBUG=fatal_warnings \
 GTEST_DEATH_TEST_USE_FORK=1 \
 $RUN_COMMAND \
   --trace-children=yes \
   --suppressions="$SUPPRESSIONS" \
   "${DEFAULT_TOOL_FLAGS[@]}" \
   "$@"