[regalloc] Enable control flow aware allocation

This is a test to see how much and where we regress. We have seen
some quirks of our current allocator that do not show up in this
new approach, so we need to decide whether to stabilize the new
allocation scheme. Performance numbers are a key indicator for that
decision.

This patch is intended to be reverted after stability and performance
numbers are in (i.e. after a few days).

Change-Id: I8df8ff7de8efa82a8abbdfa1d21d7877756f129e
Bug: v8:9088
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1552786Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60643}

src/flag-definitions.h

@@ -440,9 +440,9 @@ DEFINE_BOOL(print_deopt_stress, false, "print number of possible deopt points")
 // Flags for TurboFan.
 DEFINE_BOOL(turbo_sp_frame_access, false,
             "use stack pointer-relative access to frame wherever possible")
-DEFINE_BOOL(turbo_preprocess_ranges, true,
+DEFINE_BOOL(turbo_preprocess_ranges, false,
             "run pre-register allocation heuristics")
-DEFINE_BOOL(turbo_control_flow_aware_allocation, false,
+DEFINE_BOOL(turbo_control_flow_aware_allocation, true,
             "consider control flow while allocating registers")
 DEFINE_NEG_IMPLICATION(turbo_control_flow_aware_allocation,
                        turbo_preprocess_ranges)