From e4fbadd0518d4a4656af6f4886368b2ab42db7bb Mon Sep 17 00:00:00 2001
From: Joel Dice <git@seibutsu.mailsnare.net>
Date: Sun, 16 Dec 2007 15:41:07 -0700
Subject: [PATCH] JIT-related GC safety fixes

---
 makefile        |  6 +++---
 src/compile.cpp | 26 ++++++++++++++++++++------
 src/heap.cpp    |  6 +++---
 src/machine.cpp |  9 +++++++++
 4 files changed, 35 insertions(+), 12 deletions(-)

diff --git a/makefile b/makefile
index 241f607fd5..9754eb923e 100644
--- a/makefile
+++ b/makefile
@@ -28,7 +28,7 @@ src = src
 classpath = classpath
 test = test
 
-input = $(test-build)/Exceptions.class
+input = $(test-build)/GC.class
 
 build-cxx = g++
 build-cc = gcc
@@ -109,10 +109,10 @@ ifeq ($(mode),debug)
 	cflags += -O0 -g3
 endif
 ifeq ($(mode),stress)
-	cflags += -O0 -g3 -DNDEBUG -DVM_STRESS
+	cflags += -O0 -g3 -DVM_STRESS
 endif
 ifeq ($(mode),stress-major)
-	cflags += -O0 -g3 -DNDEBUG -DVM_STRESS -DVM_STRESS_MAJOR
+	cflags += -O0 -g3 -DVM_STRESS -DVM_STRESS_MAJOR
 endif
 ifeq ($(mode),fast)
 	cflags += -O3 -g3 -DNDEBUG
diff --git a/src/compile.cpp b/src/compile.cpp
index 23f0c64e64..f25651c16d 100644
--- a/src/compile.cpp
+++ b/src/compile.cpp
@@ -2914,6 +2914,7 @@ finish(MyThread* t, Compiler* c, object method, Vector* objectPool,
 
   if (method) {
     PROTECT(t, method);
+    PROTECT(t, result);
 
     for (unsigned i = 0; i < objectPool->length(); i += sizeof(PoolElement)) {
       PoolElement* e = objectPool->peek<PoolElement>(i);
@@ -3076,17 +3077,20 @@ void
 compile(MyThread* t, object method);
 
 void*
-compileMethod(MyThread* t)
+compileMethod2(MyThread* t)
 {
   object node = findTraceNode(t, *static_cast<void**>(t->stack));
+  PROTECT(t, node);
+
   object target = resolveTarget(t, t->stack, traceNodeTarget(t, node));
+  PROTECT(t, target);
 
   if (LIKELY(t->exception == 0)) {
     compile(t, target);
   }
 
   if (UNLIKELY(t->exception)) {
-    unwind(t);
+    return 0;
   } else {
     if (not traceNodeVirtualCall(t, node)) {
       Compiler* c = makeCompiler(t->m->system, 0);
@@ -3098,6 +3102,18 @@ compileMethod(MyThread* t)
   }
 }
 
+void*
+compileMethod(MyThread* t)
+{
+  void* r = compileMethod2(t);
+
+  if (UNLIKELY(t->exception)) {
+    unwind(t);
+  } else {
+    return r;
+  }
+}
+
 uint64_t
 invokeNative2(MyThread* t, object method)
 {
@@ -3302,7 +3318,7 @@ visitStack(MyThread* t, Heap::Visitor* v)
   void** stack = static_cast<void**>(t->stack);
   MyThread::CallTrace* trace = t->trace;
 
-  while (true) {
+  while (stack) {
     object node = findTraceNode(t, *stack);
     if (node) {
       PROTECT(t, node);
@@ -3316,7 +3332,7 @@ visitStack(MyThread* t, Heap::Visitor* v)
         visitParameters(t, v, base, method);
       }
       
-      visitStackAndLocals(t, v, base, method);
+      visitStackAndLocals(t, v, base, node);
 
       stack = static_cast<void**>(base) + 1;
       base = *static_cast<void**>(base);
@@ -3838,8 +3854,6 @@ compile(MyThread* t, object method)
     ACQUIRE(t, t->m->classLock);
     
     if (methodCompiled(t, method) == p->getDefaultCompiled(t)) {
-      PROTECT(t, method);
-
       Compiler* c = makeCompiler(t->m->system, p->indirectCaller);
     
       object compiled = compile(t, c, method);
diff --git a/src/heap.cpp b/src/heap.cpp
index 4c9921e40b..12eeb91617 100644
--- a/src/heap.cpp
+++ b/src/heap.cpp
@@ -332,7 +332,7 @@ class Segment {
   }
 
   void replaceWith(Segment* s) {
-    system(context)->free(data);
+    if (data) system(context)->free(data);
     data = s->data;
     s->data = 0;
 
@@ -350,7 +350,7 @@ class Segment {
         abort(context);
       }
     } else {
-      map = 0;
+      assert(context, map == 0);
     }    
   }
 
@@ -467,7 +467,7 @@ class Context {
     ageMap(&gen1, max(1, log(TenureThreshold)), 1, 0, false),
     gen1(this, &ageMap, 0, 0),
 
-    nextAgeMap(&nextGen1,  max(1, log(TenureThreshold)), 1, 0, false),
+    nextAgeMap(&nextGen1, max(1, log(TenureThreshold)), 1, 0, false),
     nextGen1(this, &nextAgeMap, 0, 0),
 
     pointerMap(&gen2, 1, 1, 0, true),
diff --git a/src/machine.cpp b/src/machine.cpp
index de06be8065..728da1fe83 100644
--- a/src/machine.cpp
+++ b/src/machine.cpp
@@ -2777,6 +2777,11 @@ intern(Thread* t, object s)
 void
 collect(Thread* t, Heap::CollectionType type)
 {
+#ifdef VM_STRESS
+  bool stress = t->stress;
+  if (not stress) t->stress = true;
+#endif
+
   Machine* m = t->m;
 
   m->unsafe = true;
@@ -2800,6 +2805,10 @@ collect(Thread* t, Heap::CollectionType type)
   m->heapPoolIndex = 0;
 
   m->fixedFootprint = 0;
+
+#ifdef VM_STRESS
+  if (not stress) t->stress = false;
+#endif
 }
 
 void