Re-commit optimization bisect support (r267022) without new pass manager support.

The original commit was reverted because of a buildbot problem with LazyCallGraph::SCC handling (not related to the OptBisect handling).

Differential Revision: http://reviews.llvm.org/D19172

llvm-svn: 267231

1 files changed, 18 insertions, 0 deletions

diff --git a/llvm/lib/IR/LLVMContextImpl.cpp b/llvm/lib/IR/LLVMContextImpl.cpp
index d5d9038..d27fcb1 100644
--- a/llvm/lib/IR/LLVMContextImpl.cpp
+++ b/llvm/lib/IR/LLVMContextImpl.cpp
@@ -16,6 +16,8 @@
 #include "llvm/IR/Attributes.h"
 #include "llvm/IR/DiagnosticInfo.h"
 #include "llvm/IR/Module.h"
+#include "llvm/IR/OptBisect.h"
+#include "llvm/Support/ManagedStatic.h"
 #include <algorithm>
 using namespace llvm;
 
@@ -232,3 +234,19 @@ void GetElementPtrConstantExpr::anchor() { }
 
 void CompareConstantExpr::anchor() { }
 
+/// Singleton instance of the OptBisect class.
+///
+/// This singleton is accessed via the LLVMContext::getOptBisect() function.  It
+/// provides a mechanism to disable passes and individual optimizations at
+/// compile time based on a command line option (-opt-bisect-limit) in order to
+/// perform a bisecting search for optimization-related problems.
+///
+/// Even if multiple LLVMContext objects are created, they will all return the
+/// same instance of OptBisect in order to provide a single bisect count.  Any
+/// code that uses the OptBisect object should be serialized when bisection is
+/// enabled in order to enable a consistent bisect count.
+static ManagedStatic<OptBisect> OptBisector;
+
+OptBisect &LLVMContextImpl::getOptBisect() {
+  return *OptBisector;
+}