A64: Synchronize with r15545.

src/hydrogen-sce.cc

Index: src/hydrogen-sce.cc
diff --git a/src/a64/frames-a64.cc b/src/hydrogen-sce.cc
similarity index 62%
copy from src/a64/frames-a64.cc
copy to src/hydrogen-sce.cc
index b1764e0c5fc4b2d8dc4567931990170da2dccaa0..a6995f647afc00437783f057110c7654a28265c3 100644
--- a/src/a64/frames-a64.cc
+++ b/src/hydrogen-sce.cc
@@ -25,27 +25,38 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+#include "hydrogen-sce.h"
 #include "v8.h"
 
-#if defined(V8_TARGET_ARCH_A64)
-
-#include "assembler.h"
-#include "assembler-a64.h"
-#include "assembler-a64-inl.h"
-#include "frames.h"
-
 namespace v8 {
 namespace internal {
 
-
-Register JavaScriptFrame::fp_register() { return v8::internal::fp; }
-Register JavaScriptFrame::context_register() { return cp; }
-
-
-Register StubFailureTrampolineFrame::fp_register() { return v8::internal::fp; }
-Register StubFailureTrampolineFrame::context_register() { return cp; }
-
+void HStackCheckEliminationPhase::Run() {
+  // For each loop block walk the dominator tree from the backwards branch to
+  // the loop header. If a call instruction is encountered the backwards branch
+  // is dominated by a call and the stack check in the backwards branch can be
+  // removed.
+  for (int i = 0; i < graph()->blocks()->length(); i++) {
+    HBasicBlock* block = graph()->blocks()->at(i);
+    if (block->IsLoopHeader()) {
+      HBasicBlock* back_edge = block->loop_information()->GetLastBackEdge();
+      HBasicBlock* dominator = back_edge;
+      while (true) {
+        for (HInstructionIterator it(dominator); !it.Done(); it.Advance()) {
+          if (it.Current()->IsCall()) {
+            block->loop_information()->stack_check()->Eliminate();
+            break;
+          }
+        }
+
+        // Done when the loop header is processed.
+        if (dominator == block) break;
+
+        // Move up the dominator tree.
+        dominator = dominator->dominator();
+      }
+    }
+  }
+}
 
 } }  // namespace v8::internal
-
-#endif  // V8_TARGET_ARCH_A64