[Modules] Make Support/Debug.h modular. This requires it to not change

behavior based on other files defining DEBUG_TYPE, which means it cannot
define DEBUG_TYPE at all. This is actually better IMO as it forces folks
to define relevant DEBUG_TYPEs for their files. However, it requires all
files that currently use DEBUG(...) to define a DEBUG_TYPE if they don't
already. I've updated all such files in LLVM and will do the same for
other upstream projects.

This still leaves one important change in how LLVM uses the DEBUG_TYPE
macro going forward: we need to only define the macro *after* header
files have been #include-ed. Previously, this wasn't possible because
Debug.h required the macro to be pre-defined. This commit removes that.
By defining DEBUG_TYPE after the includes two things are fixed:

- Header files that need to provide a DEBUG_TYPE for some inline code
  can do so by defining the macro before their inline code and undef-ing
  it afterward so the macro does not escape.

- We no longer have rampant ODR violations due to including headers with
  different DEBUG_TYPE definitions. This may be mostly an academic
  violation today, but with modules these types of violations are easy
  to check for and potentially very relevant.

Where necessary to suppor headers with DEBUG_TYPE, I have moved the
definitions below the includes in this commit. I plan to move the rest
of the DEBUG_TYPE macros in LLVM in subsequent commits; this one is big
enough.

The comments in Debug.h, which were hilariously out of date already,
have been updated to reflect the recommended practice going forward.

llvm-svn: 206822

4 files changed, 8 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/Utils/CodeExtractor.cpp b/llvm/lib/Transforms/Utils/CodeExtractor.cpp
index b81484277eb..4bdff5dfb35 100644
--- a/llvm/lib/Transforms/Utils/CodeExtractor.cpp
+++ b/llvm/lib/Transforms/Utils/CodeExtractor.cpp
@@ -38,6 +38,8 @@
 #include <set>
 using namespace llvm;
 
+#define DEBUG_TYPE "code-extractor"
+
 // Provide a command-line option to aggregate function arguments into a struct
 // for functions produced by the code extractor. This is useful when converting
 // extracted functions to pthread-based code, as only one argument (void*) can
diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index 9d0be8be9c4..abd73eb5c97 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -43,6 +43,8 @@
 #include "llvm/Support/raw_ostream.h"
 using namespace llvm;
 
+#define DEBUG_TYPE "local"
+
 STATISTIC(NumRemoved, "Number of unreachable basic blocks removed");
 
 //===----------------------------------------------------------------------===//
diff --git a/llvm/lib/Transforms/Utils/LowerSwitch.cpp b/llvm/lib/Transforms/Utils/LowerSwitch.cpp
index 6fb74106e3f..6d5cd780952 100644
--- a/llvm/lib/Transforms/Utils/LowerSwitch.cpp
+++ b/llvm/lib/Transforms/Utils/LowerSwitch.cpp
@@ -27,6 +27,8 @@
 #include <algorithm>
 using namespace llvm;
 
+#define DEBUG_TYPE "lower-switch"
+
 namespace {
   /// LowerSwitch Pass - Replace all SwitchInst instructions with chained branch
   /// instructions.
diff --git a/llvm/lib/Transforms/Utils/SSAUpdater.cpp b/llvm/lib/Transforms/Utils/SSAUpdater.cpp
index 28f5c44a9a9..1bf9dea1f62 100644
--- a/llvm/lib/Transforms/Utils/SSAUpdater.cpp
+++ b/llvm/lib/Transforms/Utils/SSAUpdater.cpp
@@ -11,7 +11,6 @@
 //
 //===----------------------------------------------------------------------===//
 
-#define DEBUG_TYPE "ssaupdater"
 #include "llvm/Transforms/Utils/SSAUpdater.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/TinyPtrVector.h"
@@ -28,6 +27,8 @@
 
 using namespace llvm;
 
+#define DEBUG_TYPE "ssaupdater"
+
 typedef DenseMap<BasicBlock*, Value*> AvailableValsTy;
 static AvailableValsTy &getAvailableVals(void *AV) {
   return *static_cast<AvailableValsTy*>(AV);