Fix LLVM tool --version build mode printing for MSVC

[rnk]

Summary

LLVM tools such as llc print "DEBUG build" or "Optimized build" when
passed --version. Before this change, this was implemented by checking
for the OPTIMIZE GCC macro. MSVC does not define this macro. For
MSVC, control this behavior with _DEBUG instead. It doesn't have
precisely the same meaning, but in most configurations, it will do the
right thing.

Fixes PR17752

[merge_guards_bot]

Unit tests: pass. 61086 tests passed, 0 failed and 728 were skipped.

clang-tidy: fail. Please fix clang-tidy findings.

clang-format: fail. Please format your changes with clang-format by running git-clang-format HEAD^ or applying this patch.

Build artifacts: diff.json, clang-tidy.txt, clang-format.patch, CMakeCache.txt, console-log.txt, test-results.xml

[MaskRay]

llvm/lib/Support/CommandLine.cpp

2443

LLVM_IS_OPTIMIZED_BUILD looks like more appropriate?
I thought the difference is between "optimized/non-optimized builds", not between "debug/non-debug builds".

[rnk]

llvm/lib/Support/CommandLine.cpp

2443

I figured this whole feature exists to warn users when they are running tools built in debug mode, so I felt this was the better direction. But maybe I am biased, I develop with optimizations enabled. =P

[xbolva00]

https://github.com/llvm/llvm-project/blob/74c5fac3bba77d796132c313b77c808b2165b75d/clang/include/clang/StaticAnalyzer/Core/PathSensitive/ConstraintManager.h

Worth to fix too?

[xbolva00]

llvm/lib/Support/CommandLine.cpp

2439

Move to compiler.h?

[RKSimon]

I agree the LLVM_IS_DEBUG_BUILD defs should probably be in Compiler.h

[rnk]

llvm/lib/Support/CommandLine.cpp

2439

This is the only existing use of __OPTIMIZE__ in LLVM or clang, so I would prefer to keep it local until there is another use. I hope there will never be one, it's generally not a good idea to ifdef on whether optimizations are enabled.

[xbolva00]

This comment was removed by xbolva00.

llvm/lib/Support/CommandLine.cpp

2439

Maybe you overlooked my comment but there is one more:

https://github.com/llvm/llvm-project/blob/master/clang/include/clang/StaticAnalyzer/Core/PathSensitive/ConstraintManager.h#L99

[rnk]

llvm/lib/Support/CommandLine.cpp

2439

I did, but that seems like a better candidate for #ifdef EXPENSIVE_CHECKS.

llvm/lib/Support/CommandLine.cpp

void CommandLineParser::printOptionValues() {
   for (size_t i = 0, e = Opts.size(); i != e; ++i)
     Opts[i].second->printOptionValue(MaxArgLen, PrintAllOptions);
 }
 
 static VersionPrinterTy OverrideVersionPrinter = nullptr;
 
 static std::vector<VersionPrinterTy> *ExtraVersionPrinters = nullptr;
 
+#if defined(__GNUC__)
+// GCC and GCC-compatible compilers define __OPTIMIZE__ when optimizations are
+// enabled.
+# if defined(__OPTIMIZE__)
+#  define LLVM_IS_DEBUG_BUILD 0
+# else
+#  define LLVM_IS_DEBUG_BUILD 1
+# endif
+#elif defined(_MSC_VER)
+// MSVC doesn't have a predefined macro indicating if optimizations are enabled.
+// Use _DEBUG instead. This macro actually corresponds to the choice between
+// debug and release CRTs, but it is a reasonable proxy.
+# if defined(_DEBUG)
+#  define LLVM_IS_DEBUG_BUILD 1
+# else
+#  define LLVM_IS_DEBUG_BUILD 0
+# endif
+#else
+// Otherwise, for an unknown compiler, assume this is an optimized build.
+# define LLVM_IS_DEBUG_BUILD 0
+#endif
+
 namespace {
 class VersionPrinter {
 public:
   void print() {
     raw_ostream &OS = outs();
 #ifdef PACKAGE_VENDOR
     OS << PACKAGE_VENDOR << " ";
 #else
     OS << "LLVM (http://llvm.org/):\n  ";
 #endif
     OS << PACKAGE_NAME << " version " << PACKAGE_VERSION;
 #ifdef LLVM_VERSION_INFO
     OS << " " << LLVM_VERSION_INFO;
 #endif
     OS << "\n  ";
-#ifndef __OPTIMIZE__
+#if LLVM_IS_DEBUG_BUILD
     OS << "DEBUG build";
 #else
     OS << "Optimized build";
 #endif
 #ifndef NDEBUG
     OS << " with assertions";
 #endif
 #if LLVM_VERSION_PRINTER_SHOW_HOST_TARGET_INFO