[llvm] r227423 - Use the existing build configuration parameter ENABLE_BACKTRACE to compile out all pretty stack trace support when backtraces are disabled.

[Owen Anderson]

Author: resistor
Date: Thu Jan 29 01:35:31 2015
New Revision: 227423

URL: http://llvm.org/viewvc/llvm-project?rev=227423&view=rev
Log:
Use the existing build configuration parameter ENABLE_BACKTRACE to compile out all pretty stack trace support when backtraces are disabled.

This has the nice secondary effect of allowing LLVM to continue to build
for targets without __thread or thread_local support to continue to work
so long as they build without support for backtraces.

Modified:
    llvm/trunk/lib/Support/PrettyStackTrace.cpp

Modified: llvm/trunk/lib/Support/PrettyStackTrace.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/PrettyStackTrace.cpp?rev=227423&r1=227422&r2=227423&view=diff
==============================================================================
--- llvm/trunk/lib/Support/PrettyStackTrace.cpp (original)
+++ llvm/trunk/lib/Support/PrettyStackTrace.cpp Thu Jan 29 01:35:31 2015
@@ -27,6 +27,11 @@
 
 using namespace llvm;
 
+// If backtrace support is not enabled, compile out support for pretty stack
+// traces.  This has the secondary effect of not requiring thread local storage
+// when backtrace support is disabled.
+#if ENABLE_BACKTRACE
+
 // We need a thread local pointer to manage the stack of our stack trace
 // objects, but we *really* cannot tolerate destructors running and do not want
 // to pay any overhead of synchronizing. As a consequence, we use a raw
@@ -103,16 +108,23 @@ static void CrashHandler(void *) {
 #endif
 }
 
+// ENABLE_BACKTRACE
+#endif
+
 PrettyStackTraceEntry::PrettyStackTraceEntry() {
+#if ENABLE_BACKTRACE
   // Link ourselves.
   NextEntry = PrettyStackTraceHead;
   PrettyStackTraceHead = this;
+#endif
 }
 
 PrettyStackTraceEntry::~PrettyStackTraceEntry() {
+#if ENABLE_BACKTRACE
   assert(PrettyStackTraceHead == this &&
          "Pretty stack trace entry destruction is out of order");
   PrettyStackTraceHead = getNextEntry();
+#endif
 }
 
 void PrettyStackTraceString::print(raw_ostream &OS) const {
@@ -127,15 +139,19 @@ void PrettyStackTraceProgram::print(raw_
   OS << '\n';
 }
 
+#if ENABLE_BACKTRACE
 static bool RegisterCrashPrinter() {
   sys::AddSignalHandler(CrashHandler, nullptr);
   return false;
 }
+#endif
 
 void llvm::EnablePrettyStackTrace() {
+#if ENABLE_BACKTRACE
   // The first time this is called, we register the crash printer.
   static bool HandlerRegistered = RegisterCrashPrinter();
   (void)HandlerRegistered;
+#endif
 }
 
 void LLVMEnablePrettyStackTrace() {