Remove usages of alloca() according to style guide.

src/compiler/structured-machine-assembler.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 "src/compiler/scheduler.h"
 #include "src/compiler/structured-machine-assembler.h"
 
 namespace v8 {
 namespace internal {
@@ skipping 195 matching lines @@
 void StructuredMachineAssembler::Merge(EnvironmentVector* environments,
                                        int truncate_at) {
   DCHECK(current_environment_ == NULL || current_environment_->is_dead_);
   Environment* next = new (zone()) Environment(zone(), NULL, false);
   current_environment_ = next;
   size_t n_vars = number_of_variables_;
   NodeVector& vars = next->variables_;
   vars.reserve(n_vars);
   Node** scratch = NULL;
   size_t n_envs = environments->size();
-  Environment** live_environments = reinterpret_cast<Environment**>(
-      alloca(sizeof(environments->at(0)) * n_envs));
+  Environment** live_environments = zone()->NewArray<Environment*>(n_envs);
   size_t n_live = 0;
   for (size_t i = 0; i < n_envs; i++) {
     if (environments->at(i)->is_dead_) continue;
     live_environments[n_live++] = environments->at(i);
   }
   n_envs = n_live;
   if (n_live == 0) next->is_dead_ = true;
   if (!next->is_dead_) {
     next->block_ = schedule()->NewBasicBlock();
   }
@@ skipping 15 matching lines @@
       if (val == resolved) continue;
       if (i != 0) break;
       resolved = val;
     }
     // Have to generate a phi.
     if (i < n_envs) {
       // All values thus far uninitialized, variable used out of scope.
       CHECK(resolved != NULL);
       // Init scratch buffer.
       if (scratch == NULL) {
-        scratch = static_cast<Node**>(alloca(n_envs * sizeof(resolved)));
+        scratch = zone()->NewArray<Node*>(n_envs);
       }
       for (size_t k = 0; k < i; k++) {
         scratch[k] = resolved;
       }
       for (; i < n_envs; i++) {
         scratch[i] = live_environments[i]->variables_[j];
       }
       resolved = graph()->NewNode(common()->Phi(static_cast<int>(n_envs)),
                                   static_cast<int>(n_envs), scratch);
       if (next->block_ != NULL) {
@@ skipping 391 matching lines @@
   }
   pending_header_merges_.clear();
   pending_exit_merges_.clear();
   header_environment_ = NULL;
   DCHECK(IsDone());
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8