MIPS: Refactor Map::ConstructionCount.

Port 35ff259b

Original commit message:
This combines Map::DoneInobjectSlackTracking and Map::ConstructionCount into one more generic 4-bit counter.

Counter values from 15 down to 8 are used for in-object slack tracking, values from 7 down to 0 are free to be used for a new counter when in-object slack tracking is inactive

BUG=

Review URL: https://codereview.chromium.org/780303003

Cr-Commit-Position: refs/heads/master@{#25692}

src/mips/builtins-mips.cc

@@ -382,21 +382,21 @@ static void Generate_JSConstructStubHelper(MacroAssembler* masm,
         MemOperand bit_field3 = FieldMemOperand(a2, Map::kBitField3Offset);
         // Check if slack tracking is enabled.
         __ lw(t0, bit_field3);
-        __ DecodeField<Map::ConstructionCount>(t2, t0);
-        __ Branch(&allocate, eq, t2, Operand(JSFunction::kNoSlackTracking));
+        __ DecodeField<Map::Counter>(t2, t0);
+        __ Branch(&allocate, lt, t2, Operand(Map::kSlackTrackingCounterEnd));
         // Decrease generous allocation count.
-        __ Subu(t0, t0, Operand(1 << Map::ConstructionCount::kShift));
-        __ Branch(USE_DELAY_SLOT,
-            &allocate, ne, t2, Operand(JSFunction::kFinishSlackTracking));
+        __ Subu(t0, t0, Operand(1 << Map::Counter::kShift));
+        __ Branch(USE_DELAY_SLOT, &allocate, ne, t2,
+                  Operand(Map::kSlackTrackingCounterEnd));
         __ sw(t0, bit_field3);  // In delay slot.
 
         __ Push(a1, a2, a1);  // a1 = Constructor.
         __ CallRuntime(Runtime::kFinalizeInstanceSize, 1);
 
         __ Pop(a1, a2);
-        // Slack tracking counter is kNoSlackTracking after runtime call.
-        DCHECK(JSFunction::kNoSlackTracking == 0);
-        __ mov(t2, zero_reg);
+        // Slack tracking counter is Map::kSlackTrackingCounterEnd after runtime
+        // call.
+        __ li(t2, Map::kSlackTrackingCounterEnd);
 
         __ bind(&allocate);
       }
@@ -443,8 +443,8 @@ static void Generate_JSConstructStubHelper(MacroAssembler* masm,
         Label no_inobject_slack_tracking;
 
         // Check if slack tracking is enabled.
-        __ Branch(&no_inobject_slack_tracking,
-            eq, t2, Operand(JSFunction::kNoSlackTracking));
+        __ Branch(&no_inobject_slack_tracking, lt, t2,
+                  Operand(Map::kSlackTrackingCounterEnd));
 
         // Allocate object with a slack.
         __ lbu(a0, FieldMemOperand(a2, Map::kPreAllocatedPropertyFieldsOffset));

src/mips64/builtins-mips64.cc

@@ -382,15 +382,13 @@ static void Generate_JSConstructStubHelper(MacroAssembler* masm,
         MemOperand bit_field3 = FieldMemOperand(a2, Map::kBitField3Offset);
         // Check if slack tracking is enabled.
         __ lwu(a4, bit_field3);
-        __ DecodeField<Map::ConstructionCount>(a6, a4);
-        __ Branch(&allocate,
-                  eq,
-                  a6,
-                  Operand(static_cast<int64_t>(JSFunction::kNoSlackTracking)));
+        __ DecodeField<Map::Counter>(a6, a4);
+        __ Branch(&allocate, lt, a6,
+                  Operand(static_cast<int64_t>(Map::kSlackTrackingCounterEnd)));
         // Decrease generous allocation count.
-        __ Dsubu(a4, a4, Operand(1 << Map::ConstructionCount::kShift));
-        __ Branch(USE_DELAY_SLOT,
-            &allocate, ne, a6, Operand(JSFunction::kFinishSlackTracking));
+        __ Dsubu(a4, a4, Operand(1 << Map::Counter::kShift));
+        __ Branch(USE_DELAY_SLOT, &allocate, ne, a6,
+                  Operand(Map::kSlackTrackingCounterEnd));
         __ sw(a4, bit_field3);  // In delay slot.
 
         __ Push(a1, a2, a1);  // a1 = Constructor.
@@ -446,10 +444,8 @@ static void Generate_JSConstructStubHelper(MacroAssembler* masm,
         Label no_inobject_slack_tracking;
 
         // Check if slack tracking is enabled.
-        __ Branch(&no_inobject_slack_tracking,
-                  eq,
-                  a6,
-                  Operand(static_cast<int64_t>(JSFunction::kNoSlackTracking)));
+        __ Branch(&no_inobject_slack_tracking, lt, a6,
+                  Operand(static_cast<int64_t>(Map::kSlackTrackingCounterEnd)));
 
         // Allocate object with a slack.
         __ lwu(a0, FieldMemOperand(a2, Map::kInstanceSizesOffset));