[PATCH] [lld][Core] Implement parallel_for_each

[Rui Ueyama]

================
Comment at: include/lld/Core/Parallel.h:300
@@ +299,3 @@
+  const ptrdiff_t minParallelSizeForEach = 1024;
+  int64_t length = distance(begin, end);
+  int64_t taskSize = (length < minParallelSizeForEach)
----------------
Does this compile without std::?

================
Comment at: include/lld/Core/Parallel.h:303
@@ +302,3 @@
+                         ? length
+                         : length / minParallelSizeForEach;
+  while (taskSize <= distance(begin, end)) {
----------------
This expression doesn't make sense again. You divide length of the array with minSize, which is equal to how many minSize chunks in the array. It's not a task size.

Let's make this simple as a starter. Just set 1024 to taskSize unconditionally. That's probably large enough. You may still have to run a test with that number, though.

================
Comment at: include/lld/Core/Parallel.h:304
@@ +303,3 @@
+                         : length / minParallelSizeForEach;
+  while (taskSize <= distance(begin, end)) {
+    tg.spawn([=, &func, &tg] { std::for_each(begin, begin + taskSize, func); });
----------------
This doesn't seem to compile with std::.

http://reviews.llvm.org/D8348

EMAIL PREFERENCES
  http://reviews.llvm.org/settings/panel/emailpreferences/