[regalloc] Make turbo_preprocess_ranges the default

This CL removes the flag '--turbo-preprocess-ranges' and enables it by
default.

If FLAG_turbo_control_flow_aware_allocation is set,
--turbo-preprocess-ranges is disabled and control flow aware
allocation is enabled instead.

Bug: v8:9088
Change-Id: I81d56f15efc8f765e317aa828d27f415f8b7fd40
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1585725
Auto-Submit: Sigurd Schneider <sigurds@chromium.org>
Commit-Queue: Jaroslav Sevcik <jarin@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61070}

src/flag-definitions.h

@@ -439,12 +439,8 @@ 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,
-            "run pre-register allocation heuristics")
 DEFINE_BOOL(turbo_control_flow_aware_allocation, false,
             "consider control flow while allocating registers")
-DEFINE_NEG_IMPLICATION(turbo_control_flow_aware_allocation,
-                       turbo_preprocess_ranges)
 
 DEFINE_STRING(turbo_filter, "*", "optimization filter for TurboFan compiler")
 DEFINE_BOOL(trace_turbo, false, "trace generated TurboFan IR")

src/optimized-compilation-info.cc

@@ -91,8 +91,7 @@ void OptimizedCompilationInfo::ConfigureFlags() {
 
   if (FLAG_turbo_control_flow_aware_allocation) {
     MarkAsTurboControlFlowAwareAllocation();
-  }
-  if (FLAG_turbo_preprocess_ranges) {
+  } else {
     MarkAsTurboPreprocessRanges();
   }
 }

test/unittests/compiler/regalloc/register-allocator-unittest.cc

@@ -625,22 +625,18 @@ TEST_F(RegisterAllocatorTest, SingleDeferredBlockSpill) {
 
   const int var_def_index = 1;
   const int call_index = 3;
-  const bool spill_in_deferred =
-      FLAG_turbo_preprocess_ranges || FLAG_turbo_control_flow_aware_allocation;
-  int expect_no_moves = spill_in_deferred ? var_def_index : call_index;
-  int expect_spill_move = spill_in_deferred ? call_index : var_def_index;
 
-  // We should have no parallel moves at the "expect_no_moves" position.
+  // We should have no parallel moves at the "var_def_index" position.
   EXPECT_EQ(
-      0, GetParallelMoveCount(expect_no_moves, Instruction::START, sequence()));
+      0, GetParallelMoveCount(var_def_index, Instruction::START, sequence()));
 
-  // The spill should be performed at the position expect_spill_move.
-  EXPECT_TRUE(IsParallelMovePresent(expect_spill_move, Instruction::START,
-                                    sequence(), Reg(0), Slot(0)));
+  // The spill should be performed at the position "call_index".
+  EXPECT_TRUE(IsParallelMovePresent(call_index, Instruction::START, sequence(),
+                                    Reg(0), Slot(0)));
 }
 
 TEST_F(RegisterAllocatorTest, MultipleDeferredBlockSpills) {
-  if (!FLAG_turbo_preprocess_ranges) return;
+  if (FLAG_turbo_control_flow_aware_allocation) return;
 
   StartBlock();  // B0
   auto var1 = EmitOI(Reg(0));