Add convergent property to CodeMetrics.

[jlebar]

Summary

No functional changes.

[arsenm]

LGTM

include/llvm/Analysis/CodeMetrics.h

struct CodeMetrics {
   bool isRecursive = false;
 
   /// \brief True if this function cannot be duplicated.
   ///
   /// True if this function contains one or more indirect branches, or it contains
   /// one or more 'noduplicate' instructions.
   bool notDuplicatable = false;
 
+  /// \brief True if this function contains a call to a convergent function.
+  bool convergent = false;
+
   /// \brief True if this function calls alloca (in the C sense).
   bool usesDynamicAlloca = false;
 
   /// \brief Number of instructions in the analyzed blocks.
   unsigned NumInsts = false;
 
   /// \brief Number of analyzed blocks.
   unsigned NumBlocks = false;

lib/Analysis/CodeMetrics.cpp

for (BasicBlock::const_iterator II = BB->begin(), E = BB->end();
     }
 
     if (isa<ExtractElementInst>(II) || II->getType()->isVectorTy())
       ++NumVectorInsts;
 
     if (II->getType()->isTokenTy() && II->isUsedOutsideOfBlock(BB))
       notDuplicatable = true;
 
-    if (const CallInst *CI = dyn_cast<CallInst>(II))
+    if (const CallInst *CI = dyn_cast<CallInst>(II)) {
       if (CI->cannotDuplicate())
         notDuplicatable = true;
+      if (CI->isConvergent())
+        convergent = true;
+    }
 
     if (const InvokeInst *InvI = dyn_cast<InvokeInst>(II))
       if (InvI->cannotDuplicate())
         notDuplicatable = true;
 
     NumInsts += TTI.getUserCost(&*II);
   }