[Turbofan] Run loop peeling concurrently.

BUG=v8:5428

Review-Url: https://codereview.chromium.org/2613463002
Cr-Commit-Position: refs/heads/master@{#42038}

src/compiler/pipeline.cc

@@ -1542,14 +1542,6 @@ bool PipelineImpl::CreateGraph() {
     // Lower JSOperators where we can determine types.
     Run<TypedLoweringPhase>();
     RunPrintAndVerify("Lowered typed");
-
-    if (data->info()->is_loop_peeling_enabled()) {
-      Run<LoopPeelingPhase>();
-      RunPrintAndVerify("Loops peeled", true);
-    } else {
-      Run<LoopExitEliminationPhase>();
-      RunPrintAndVerify("Loop exits eliminated", true);
-    }
   }
 
   // Do some hacky things to prepare for the optimization phase.
@@ -1564,6 +1556,14 @@ bool PipelineImpl::CreateGraph() {
 bool PipelineImpl::OptimizeGraph(Linkage* linkage) {
   PipelineData* data = this->data_;
 
+  if (data->info()->is_loop_peeling_enabled()) {
+    Run<LoopPeelingPhase>();
+    RunPrintAndVerify("Loops peeled", true);
+  } else {
+    Run<LoopExitEliminationPhase>();
+    RunPrintAndVerify("Loop exits eliminated", true);
+  }
+
   if (!data->is_asm()) {
     if (FLAG_turbo_load_elimination) {
       Run<LoadEliminationPhase>();