[turbofan] use START and END gap positions for constraints

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

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/pipeline.h"
 #include "test/unittests/compiler/instruction-sequence-unittest.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
@@ skipping 376 matching lines @@
 
   // Outer diamond merge.
   StartBlock();
   auto phi = Phi(l_phi, r_phi);
   Return(Reg(phi));
   EndBlock();
 
   Allocate();
 }
 
+
+TEST_F(RegisterAllocatorTest, RegressionSplitBeforeAndMove) {
+  StartBlock();
+
+  // Fill registers.
+  VReg values[kDefaultNRegs];
+  for (size_t i = 0; i < arraysize(values); ++i) {
+    if (i == 0 || i == 1) continue;  // Leave a hole for c_1 to take.
+    values[i] = Define(Reg(static_cast<int>(i)));
+  }
+
+  auto c_0 = DefineConstant();
+  auto c_1 = DefineConstant();
+
+  EmitOI(Reg(1), Reg(c_0, 0), UniqueReg(c_1));
+
+  // Use previous values to force c_1 to split before the previous instruction.
+  for (size_t i = 0; i < arraysize(values); ++i) {
+    if (i == 0 || i == 1) continue;
+    EmitI(Reg(values[i], static_cast<int>(i)));
+  }
+
+  EndBlock(Last());
+
+  Allocate();
+}
+
+
+TEST_F(RegisterAllocatorTest, RegressionSpillTwice) {
+  StartBlock();
+  auto p_0 = Parameter(Reg(1));
+  EmitCall(Slot(-2), Unique(p_0), Reg(p_0, 1));
+  EndBlock(Last());
+
+  Allocate();
+}
+
+
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8