commit b090a18e4292dc339a3b2668bf6dc855928dee3a
author Dave Allison <dallison@google.com> Thu Aug 14 17:02:48 2014 +0000
committer Dave Allison <dallison@google.com> Tue Aug 19 09:30:39 2014 -0700
tree fa12ca73ca33f48e2d2a1539db830a63996f8161
parent 75dd98835859ca98c9f98339da8b64640d09a175

Merge stack usage reduction for overflow checks

Cherry pick from: b038ba66a166fb264ca121632f447712e0973b5b

Change-Id: I19999e72ff731d4fc73d91b9ff767de5858c15ee

runtime/entrypoints/entrypoint_utils.cc

diff --git a/runtime/entrypoints/entrypoint_utils.cc b/runtime/entrypoints/entrypoint_utils.cc
index a0e35f8..cf89850 100644
--- a/runtime/entrypoints/entrypoint_utils.cc
+++ b/runtime/entrypoints/entrypoint_utils.cc
@@ -211,7 +211,7 @@
   }
 
   bool explicit_overflow_check = Runtime::Current()->ExplicitStackOverflowChecks();
-  self->ResetDefaultStackEnd(!explicit_overflow_check);  // Return to default stack size.
+  self->ResetDefaultStackEnd();  // Return to default stack size.
 
   // And restore protection if implicit checks are on.
   if (!explicit_overflow_check) {

runtime/thread.cc

diff --git a/runtime/thread.cc b/runtime/thread.cc
index dcc897f..d5163a8 100644
--- a/runtime/thread.cc
+++ b/runtime/thread.cc
@@ -224,7 +224,8 @@
   } else {
     // If we are going to use implicit stack checks, allocate space for the protected
     // region at the bottom of the stack.
-    stack_size += Thread::kStackOverflowImplicitCheckSize;
+    stack_size += Thread::kStackOverflowImplicitCheckSize +
+        GetStackOverflowReservedBytes(kRuntimeISA);
   }
 
   // Some systems require the stack size to be a multiple of the system page size, so round up.
@@ -264,7 +265,7 @@
   // a segv.
 
   // Read every page from the high address to the low.
-  for (byte* p = stack_top; p > pregion; p -= kPageSize) {
+  for (byte* p = stack_top; p >= pregion; p -= kPageSize) {
     dont_optimize_this = *p;
   }
 
@@ -539,7 +540,7 @@
 
   // Set stack_end_ to the bottom of the stack saving space of stack overflows
   bool implicit_stack_check = !Runtime::Current()->ExplicitStackOverflowChecks();
-  ResetDefaultStackEnd(implicit_stack_check);
+  ResetDefaultStackEnd();
 
   // Install the protected region if we are doing implicit overflow checks.
   if (implicit_stack_check) {
@@ -551,8 +552,8 @@
     // The thread might have protected region at the bottom.  We need
     // to install our own region so we need to move the limits
     // of the stack to make room for it.
-    tlsPtr_.stack_begin += guardsize;
-    tlsPtr_.stack_end += guardsize;
+    tlsPtr_.stack_begin += guardsize + kStackOverflowProtectedSize;
+    tlsPtr_.stack_end += guardsize + kStackOverflowProtectedSize;
     tlsPtr_.stack_size -= guardsize;
 
     InstallImplicitProtection();

runtime/thread.h

diff --git a/runtime/thread.h b/runtime/thread.h
index 120ff6f..fe950c4 100644
--- a/runtime/thread.h
+++ b/runtime/thread.h
@@ -594,16 +594,10 @@
   void SetStackEndForStackOverflow() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
 
   // Set the stack end to that to be used during regular execution
-  void ResetDefaultStackEnd(bool implicit_overflow_check) {
+  void ResetDefaultStackEnd() {
     // Our stacks grow down, so we want stack_end_ to be near there, but reserving enough room
     // to throw a StackOverflowError.
-    if (implicit_overflow_check) {
-      // For implicit checks we also need to add in the protected region above the
-      // overflow region.
-      tlsPtr_.stack_end = tlsPtr_.stack_begin + kStackOverflowImplicitCheckSize;
-    } else {
-      tlsPtr_.stack_end = tlsPtr_.stack_begin + GetStackOverflowReservedBytes(kRuntimeISA);
-    }
+    tlsPtr_.stack_end = tlsPtr_.stack_begin + GetStackOverflowReservedBytes(kRuntimeISA);
   }
 
   // Install the protected region for implicit stack checks.