Fix compile errors arising from compiling breakpad with clang.

These compile errors occur when building the check target with:
CXX=clang++-3.8
CXXFLAGS="-Werror -Wconstant-conversion -g -O2 -std=c++11"

src/processor/stackwalker_mips.cc:60:9: error: comparison of constant
  18446744073709551615 with expression of type 'bool' is always false
  [Werror,-Wtautological-constant-out-of-range-compare]
        > 0xffffffffffffffff) {
        ^ ~~~~~~~~~~~~~~~~~~
src/processor/stackwalker_mips.cc:68:66: error: comparison of constant
  4294967295 with expression of type 'bool' is always false
  [-Werror,-Wtautological-constant-out-of-range-compare]
    if ((memory_ && memory_->GetBase() + memory_->GetSize() - 1) > 0xffffffff) {
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ^ ~~~~~~~~~~

Change-Id: I29eed8f4a67b9feeb274aa1fc6c79a019135e8d6
Reviewed-on: https://chromium-review.googlesource.com/438445
Reviewed-by: Mike Frysinger <vapier@chromium.org>

1 files changed, 17 insertions, 16 deletions

diff --git a/src/processor/stackwalker_mips.cc b/src/processor/stackwalker_mips.cc
index f6368509..a3df84c4 100644
--- a/src/processor/stackwalker_mips.cc
+++ b/src/processor/stackwalker_mips.cc
@@ -55,22 +55,23 @@ StackwalkerMIPS::StackwalkerMIPS(const SystemInfo* system_info,
                                  StackFrameSymbolizer* resolver_helper)
 : Stackwalker(system_info, memory, modules, resolver_helper),
   context_(context) {
-  if (context_->context_flags & MD_CONTEXT_MIPS64 ) {
-    if ((memory_ && memory_->GetBase() + memory_->GetSize() - 1)
-        > 0xffffffffffffffff) {
-      BPLOG(ERROR) << "Memory out of range for stackwalking mips64: "
-          << HexString(memory_->GetBase())
-          << "+"
-          << HexString(memory_->GetSize());
-      memory_ = NULL;
-    }
-  } else {
-    if ((memory_ && memory_->GetBase() + memory_->GetSize() - 1) > 0xffffffff) {
-      BPLOG(ERROR) << "Memory out of range for stackwalking mips32: "
-          << HexString(memory_->GetBase())
-          << "+"
-          << HexString(memory_->GetSize());
-      memory_ = NULL;
+  if (memory_) {
+    if (context_->context_flags & MD_CONTEXT_MIPS64 ) {
+      if (0xffffffffffffffff - memory_->GetBase() < memory_->GetSize() - 1) {
+        BPLOG(ERROR) << "Memory out of range for stackwalking mips64: "
+            << HexString(memory_->GetBase())
+            << "+"
+            << HexString(memory_->GetSize());
+        memory_ = NULL;
+      }
+    } else {
+      if (0xffffffff - memory_->GetBase() < memory_->GetSize() - 1) {
+        BPLOG(ERROR) << "Memory out of range for stackwalking mips32: "
+            << HexString(memory_->GetBase())
+            << "+"
+            << HexString(memory_->GetSize());
+        memory_ = NULL;
+      }
     }
   }
 }