Improve comments after 8404aeb56a.

llvm/include/llvm/Support/ThreadPool.h

@@ -43,7 +43,7 @@ public:
   /// Construct a pool using the hardware strategy \p S for mapping hardware
   /// execution resources (threads, cores, CPUs)
   /// Defaults to using the maximum execution resources in the system, but
-  /// excluding any resources contained in the affinity mask.
+  /// accounting for the affinity mask.
   ThreadPool(ThreadPoolStrategy S = hardware_concurrency());
 
   /// Blocking destructor: the pool will wait for all the threads to complete.

llvm/include/llvm/Support/Threading.h

@@ -148,8 +148,9 @@ void llvm_execute_on_thread_async(
   class ThreadPoolStrategy {
   public:
     // The default value (0) means all available threads should be used,
-    // excluding affinity mask. If set, this value only represents a suggested
-    // high bound, the runtime might choose a lower value (not higher).
+    // taking the affinity mask into account. If set, this value only represents
+    // a suggested high bound, the runtime might choose a lower value (not
+    // higher).
     unsigned ThreadsRequested = 0;
 
     // If SMT is active, use hyper threads. If false, there will be only one
@@ -172,7 +173,7 @@ void llvm_execute_on_thread_async(
   /// be less efficient. Avoid this strategy if doing lots of I/O. Currently
   /// based on physical cores, if available for the host system, otherwise falls
   /// back to hardware_concurrency(). Returns 1 when LLVM is configured with
-  /// LLVM_ENABLE_THREADS = OFF
+  /// LLVM_ENABLE_THREADS = OFF.
   inline ThreadPoolStrategy
   heavyweight_hardware_concurrency(unsigned ThreadCount = 0) {
     ThreadPoolStrategy S;
@@ -219,7 +220,7 @@ void llvm_execute_on_thread_async(
 
   /// Returns a mask that represents on which hardware thread, core, CPU, NUMA
   /// group, the calling thread can be executed. On Windows, threads cannot
-  /// cross CPU boundaries.
+  /// cross CPU sockets boundaries.
   llvm::BitVector get_thread_affinity_mask();
 
   /// Returns how many physical CPUs or NUMA groups the system has.

llvm/lib/LTO/ThinLTOCodeGenerator.cpp

@@ -80,7 +80,9 @@ extern cl::opt<std::string> RemarksFormat;
 
 namespace {
 
-// Default to using one job per hardware core in the system
+// Default to using all available threads in the system, but using only one
+// thred per core, as indicated by the usage of
+// heavyweight_hardware_concurrency() below.
 static cl::opt<int> ThreadCount("threads", cl::init(0));
 
 // Simple helper to save temporary files for debug.

llvm/tools/llvm-lto2/llvm-lto2.cpp

@@ -65,7 +65,9 @@ static cl::opt<bool>
                                        "import files for the "
                                        "distributed backend case"));
 
-// Default to using all hardware cores in the system.
+// Default to using all available threads in the system, but using only one
+// thread per core, as indicated by the usage of
+// heavyweight_hardware_concurrency() in the InProcessThinBackend constructor.
 static cl::opt<int> Threads("thinlto-threads", cl::init(0));
 
 static cl::list<std::string> SymbolResolutions(