Make VerifyDonInfo and VerifyLoopInfo global variables

[sepavloff]

Summary

Verifications of dominator tree and loop info are expensive operations
so they are disabled by default. They can be enabled by command line
options -verify-dom-info and -verify-loop-info. These options however
enable checks only in files Dominators.cpp and LoopInfo.cpp. If some
transformation changes dominaror tree and/or loop info, it would be
convenient to place similar checks to the files implementing the
transformation.

This change makes corresponding flags global, so they can be used in
any file to optionally turn verification on.

[mzolotukhin]

Looks good to me!

Michael

[sepavloff]

Committed in r292889.

include/llvm/Support/Debug.h

 #ifndef LLVM_SUPPORT_DEBUG_H
 #define LLVM_SUPPORT_DEBUG_H
 
 namespace llvm {
 
 class raw_ostream;
 
 #ifndef NDEBUG
-/// DebugFlag - This boolean is set to true if the '-debug' command line option
-/// is specified.  This should probably not be referenced directly, instead, use
-/// the DEBUG macro below.
-///
-extern bool DebugFlag;
 
 /// isCurrentDebugType - Return true if the specified string is the debug type
 /// specified on the command line, or if none was specified on the command line
 /// with the -debug-only=X option.
 ///
 bool isCurrentDebugType(const char *Type);
 
 /// setCurrentDebugType - Set the current debug type, as if the -debug-only=X

 
 #else
 #define isCurrentDebugType(X) (false)
 #define setCurrentDebugType(X)
 #define setCurrentDebugTypes(X, N)
 #define DEBUG_WITH_TYPE(TYPE, X) do { } while (false)
 #endif
 
+/// This boolean is set to true if the '-debug' command line option
+/// is specified.  This should probably not be referenced directly, instead, use
+/// the DEBUG macro below.
+///
+extern bool DebugFlag;
+
+/// \name Verification flags.
+///
+/// These flags turns on/off that are expensive and are turned off by default,
+/// unless macro EXPENSIVE_CHECKS is defined. The flags allow selectively
+/// turning the checks on without need to recompile.
+/// \{
+
+/// Enables verification of dominator trees.
+///
+extern bool VerifyDomInfo;
+
+/// Enables verification of loop info.
+///
+extern bool VerifyLoopInfo;
+
+///\}
+
 /// EnableDebugBuffering - This defaults to false.  If true, the debug
 /// stream will install signal handlers to dump any buffered debug
 /// output.  It allows clients to selectively allow the debug stream
 /// to install signal handlers if they are certain there will be no
 /// conflict.
 ///
 extern bool EnableDebugBuffering;
 

lib/Analysis/LoopInfo.cpp

 using namespace llvm;
 
 // Explicitly instantiate methods in LoopInfoImpl.h for IR-level Loops.
 template class llvm::LoopBase<BasicBlock, Loop>;
 template class llvm::LoopInfoBase<BasicBlock, Loop>;
 
 // Always verify loopinfo if expensive checking is enabled.
 #ifdef EXPENSIVE_CHECKS
-static bool VerifyLoopInfo = true;
+bool llvm::VerifyLoopInfo = true;
 #else
-static bool VerifyLoopInfo = false;
+bool llvm::VerifyLoopInfo = false;
 #endif
 static cl::opt<bool,true>
 VerifyLoopInfoX("verify-loop-info", cl::location(VerifyLoopInfo),
                 cl::desc("Verify loop info (time consuming)"));
 
 //===----------------------------------------------------------------------===//
 // Loop implementation
 //

lib/IR/Dominators.cpp

 #include "llvm/Support/Debug.h"
 #include "llvm/Support/GenericDomTreeConstruction.h"
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
 using namespace llvm;
 
 // Always verify dominfo if expensive checking is enabled.
 #ifdef EXPENSIVE_CHECKS
-static bool VerifyDomInfo = true;
+bool llvm::VerifyDomInfo = true;
 #else
-static bool VerifyDomInfo = false;
+bool llvm::VerifyDomInfo = false;
 #endif
 static cl::opt<bool,true>
 VerifyDomInfoX("verify-dom-info", cl::location(VerifyDomInfo),
                cl::desc("Verify dominator info (time consuming)"));
 
 bool BasicBlockEdge::isSingleEdge() const {
   const TerminatorInst *TI = Start->getTerminator();
   unsigned NumEdgesToEnd = 0;