[PartiallyInlineLibCalls] Add DebugCounter support

This adds DebugCounter support to the PartiallyInlineLibCalls pass,
which should make debugging/automated bisection easier in the future.

Patch by Zhizhou Yang!

Differential Revision: https://reviews.llvm.org/D50093

llvm-svn: 342172
diff --git a/llvm/lib/Transforms/Scalar/PartiallyInlineLibCalls.cpp b/llvm/lib/Transforms/Scalar/PartiallyInlineLibCalls.cpp
index 1748815..05ea914 100644
--- a/llvm/lib/Transforms/Scalar/PartiallyInlineLibCalls.cpp
+++ b/llvm/lib/Transforms/Scalar/PartiallyInlineLibCalls.cpp
@@ -17,6 +17,7 @@
 #include "llvm/Analysis/TargetLibraryInfo.h"
 #include "llvm/Analysis/TargetTransformInfo.h"
 #include "llvm/IR/IRBuilder.h"
+#include "llvm/Support/DebugCounter.h"
 #include "llvm/Transforms/Scalar.h"
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
 
@@ -24,6 +25,8 @@
 
 #define DEBUG_TYPE "partially-inline-libcalls"
 
+DEBUG_COUNTER(PILCounter, "partially-inline-libcalls-transform",
+              "Controls transformations in partially-inline-libcalls");
 
 static bool optimizeSQRT(CallInst *Call, Function *CalledFunc,
                          BasicBlock &CurrBB, Function::iterator &BB,
@@ -33,6 +36,9 @@
   if (Call->onlyReadsMemory())
     return false;
 
+  if (!DebugCounter::shouldExecute(PILCounter))
+    return false;
+
   // Do the following transformation:
   //
   // (before)