Add a Statistic for speculative inlinings.

Summary:
It would be good to have a compiler statistic to tell how many inlinings are speculative.

This diff adds that.

Reviewed By: avp

Differential Revision: D70132784

fbshipit-source-id: 2dceec02cd694aa1fe962dd8505f48cbe7194529

lib/Optimizer/Scalar/Inlining.cpp

@@ -21,6 +21,9 @@
 #include "llvh/Support/Debug.h"
 
 STATISTIC(NumInlinedCalls, "Number of inlined calls");
+STATISTIC(
+    NumSpecInlinedCalls,
+    "Number of inlined calls that are speculatively inlined");
 
 namespace hermes {
 
@@ -635,6 +638,8 @@ bool Inlining::runOnModule(Module *M) {
 
         // Continue inserting in inlineBB.
         builder.setInsertionBlock(inlineBB);
+
+        ++NumSpecInlinedCalls;
       }
 
       auto *returnValue = inlineFunction(builder, FC, CI, nextBlock);