[vm/compiler] Simplify range analysis by removing range sizes

Concept of range sizes is artificial and sometimes over-approximated
as it doesn't match representations used in IL instructions.
It is replaced by "full range" derived from representation.

Also, this change removes a bit of Smi-specific logic which cannot be
extended for arbitrary integers.

TEST=ci

Change-Id: Ifc3092b13e4655cd5790d39d3fb88bd9b40ba484
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/396481
Reviewed-by: Slava Egorov <[email protected]>
Commit-Queue: Alexander Markov <[email protected]>

Author: alexmarkov

runtime/vm/compiler/backend/flow_graph.cc

@@ -2177,10 +2177,9 @@ class PhiUnboxingHeuristic : public ValueObject {
         // If all the inputs are unboxed integers but with different
         // representations, then pick a representation based on the range
         // of values that flow into the phi node.
-        new_representation =
-            RangeUtils::Fits(phi->range(), RangeBoundary::kRangeBoundaryInt32)
-                ? kUnboxedInt32
-                : kUnboxedInt64;
+        new_representation = Range::Fits(phi->range(), kUnboxedInt32)
+                                 ? kUnboxedInt32
+                                 : kUnboxedInt64;
       }
 
       // Decide if it is worth to unbox an boxed integer phi.
@@ -2202,10 +2201,9 @@ class PhiUnboxingHeuristic : public ValueObject {
         const bool flows_into_unboxed_use = FlowsIntoUnboxedUse(phi);
 
         if (has_unboxed_incoming_value && flows_into_unboxed_use) {
-          new_representation =
-              RangeUtils::Fits(phi->range(), RangeBoundary::kRangeBoundaryInt32)
-                  ? kUnboxedInt32
-                  : kUnboxedInt64;
+          new_representation = Range::Fits(phi->range(), kUnboxedInt32)
+                                   ? kUnboxedInt32
+                                   : kUnboxedInt64;
         }
 #endif
       }

runtime/vm/compiler/backend/il.cc

@@ -3182,7 +3182,8 @@ Definition* UnboxLaneInstr::Canonicalize(FlowGraph* flow_graph) {
 
 bool BoxIntegerInstr::ValueFitsSmi() const {
   Range* range = value()->definition()->range();
-  return RangeUtils::Fits(range, RangeBoundary::kRangeBoundarySmi);
+  return RangeUtils::IsWithin(range, compiler::target::kSmiMin,
+                              compiler::target::kSmiMax);
 }
 
 Definition* BoxIntegerInstr::Canonicalize(FlowGraph* flow_graph) {