RFC: Remove redundant Begin/End form signpost format strings.

[aprantl]

Summary

The API already captures the begin/end part and in Instruments, this just adds visual noise that gets in the way of the interesting data. In fact, we may not even want to print anything in the end signpost if the string is identical with the begin signpost string.

[jroelofs]

LGTM

[aprantl]

I just confirmed that passing an empty string for the end event looks even better in Instruments.

llvm/lib/Support/Signposts.cpp

bool isEnabled() const {
     return false;
   }
 
   void startInterval(const void *O, llvm::StringRef Name) {
     if (isEnabled()) {
       if (SIGNPOSTS_AVAILABLE()) {
         // Both strings used here are required to be constant literal strings.
         os_signpost_interval_begin(getLogger(), getSignpostForObject(O),
-                                   "LLVM Timers", "Begin %s", Name.data());
+                                   "LLVM Timers", "%s", Name.data());
       }
     }
   }
 
   void endInterval(const void *O, llvm::StringRef Name) {
     if (isEnabled()) {
       if (SIGNPOSTS_AVAILABLE()) {
         // Both strings used here are required to be constant literal strings.
         os_signpost_interval_end(getLogger(), getSignpostForObject(O),
-                                 "LLVM Timers", "End %s", Name.data());
+                                 "LLVM Timers", "");
       }
     }
   }
 };
 } // end namespace llvm
 #else
 /// Definition necessary for use of std::unique_ptr in SignpostEmitter::Impl.
 class llvm::SignpostEmitterImpl {};