Implement a simple register allocator that tries to keep instruction results in registers.

runtime/vm/locations.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/locations.h"
 
 #include "vm/intermediate_language.h"
+#include "vm/flow_graph_compiler.h"
 
 namespace dart {
 
-
-static Register AllocateFreeRegister(
-    EmbeddedArray<bool, kNumberOfCpuRegisters>* blocked_registers) {
-  for (intptr_t regno = 0; regno < kNumberOfCpuRegisters; regno++) {
-    if (!blocked_registers->At(regno)) {
-      blocked_registers->SetAt(regno, true);
-      return static_cast<Register>(regno);
-    }
-  }
-  UNREACHABLE();
-  return kNoRegister;
-}
-
-
-void LocationSummary::AllocateRegisters() {
-  EmbeddedArray<bool, kNumberOfCpuRegisters> blocked_registers;
-
-  // Mark all available registers free.
-  for (intptr_t i = 0; i < kNumberOfCpuRegisters; i++) {
-    blocked_registers[i] = false;
-  }
-
-  // Mark all fixed input, temp and output registers as used.
-  for (intptr_t i = 0; i < input_count(); i++) {
-    Location loc = in(i);
-    if (loc.kind() == Location::kRegister) {
-      ASSERT(!blocked_registers[loc.reg()]);
-      blocked_registers[loc.reg()] = true;
-    }
-  }
-
-  for (intptr_t i = 0; i < temp_count(); i++) {
-    Location loc = temp(i);
-    if (loc.kind() == Location::kRegister) {
-      ASSERT(!blocked_registers[loc.reg()]);
-      blocked_registers[loc.reg()] = true;
-    }
-  }
-
-  if (out().kind() == Location::kRegister) {
-    // Fixed output registers are allowed to overlap with
-    // temps and inputs.
-    blocked_registers[out().reg()] = true;
-  }
-
-  // Do not allocate known registers.
-  blocked_registers[CTX] = true;
-  blocked_registers[SPREG] = true;
-  blocked_registers[FPREG] = true;
-  if (TMP != kNoRegister) {
-    blocked_registers[TMP] = true;
-  }
-
-  // Allocate all unallocated input locations.
-  for (intptr_t i = 0; i < input_count(); i++) {
-    Location loc = in(i);
-    if (loc.kind() == Location::kUnallocated) {
-      ASSERT(loc.policy() == Location::kRequiresRegister);
-      set_in(i, Location::RegisterLocation(
-          AllocateFreeRegister(&blocked_registers)));
-    }
-  }
-
-  // Allocate all unallocated temp locations.
-  for (intptr_t i = 0; i < temp_count(); i++) {
-    Location loc = temp(i);
-    if (loc.kind() == Location::kUnallocated) {
-      ASSERT(loc.policy() == Location::kRequiresRegister);
-      set_temp(i, Location::RegisterLocation(
-          AllocateFreeRegister(&blocked_registers)));
-    }
-  }
-
-  Location result_location = out();
-  if (result_location.kind() == Location::kUnallocated) {
-    switch (result_location.policy()) {
-      case Location::kRequiresRegister:
-        result_location = Location::RegisterLocation(
-            AllocateFreeRegister(&blocked_registers));
-        break;
-      case Location::kSameAsFirstInput:
-        result_location = in(0);
-        break;
-    }
-    set_out(result_location);
-  }
-}
-
-
-LocationSummary* LocationSummary::Make(intptr_t input_count, Location out) {
-  LocationSummary* summary = new LocationSummary(input_count, 0);
+LocationSummary* LocationSummary::Make(intptr_t input_count,
+                                       Location out,
+                                       ContainsCall contains_call,
+                                       ContainsBranch contains_branch) {
+  LocationSummary* summary = new LocationSummary(input_count,
+                                                 0,
+                                                 contains_call,
+                                                 contains_branch);
   for (intptr_t i = 0; i < input_count; i++) {
     summary->set_in(i, Location::RequiresRegister());
   }
   summary->set_out(out);
   return summary;
 }
 
 }  // namespace dart