From 06299adb2121ff3ee27a8ecb5fb2312bdf8080a2 Mon Sep 17 00:00:00 2001
From: never <unknown>
Date: Tue, 5 Apr 2011 00:31:09 -0700
Subject: [PATCH] 6777083: assert(target != __null,"must not be null")
 Reviewed-by: iveresov, kvn

---
 src/cpu/x86/vm/assembler_x86.hpp | 12 ++++++++++--
 src/share/vm/code/relocInfo.cpp  | 18 ++++++------------
 src/share/vm/code/relocInfo.hpp  | 10 ++++++++++
 3 files changed, 26 insertions(+), 14 deletions(-)

diff --git a/src/cpu/x86/vm/assembler_x86.hpp b/src/cpu/x86/vm/assembler_x86.hpp
index 6ef01cbb4..2457f18bd 100644
--- a/src/cpu/x86/vm/assembler_x86.hpp
+++ b/src/cpu/x86/vm/assembler_x86.hpp
@@ -385,10 +385,18 @@ class OopAddress: public AddressLiteral {
 };
 
 class ExternalAddress: public AddressLiteral {
+ private:
+  static relocInfo::relocType reloc_for_target(address target) {
+    // Sometimes ExternalAddress is used for values which aren't
+    // exactly addresses, like the card table base.
+    // external_word_type can't be used for values in the first page
+    // so just skip the reloc in that case.
+    return external_word_Relocation::can_be_relocated(target) ? relocInfo::external_word_type : relocInfo::none;
+  }
 
-  public:
+ public:
 
-  ExternalAddress(address target) : AddressLiteral(target, relocInfo::external_word_type){}
+  ExternalAddress(address target) : AddressLiteral(target, reloc_for_target(target)) {}
 
 };
 
diff --git a/src/share/vm/code/relocInfo.cpp b/src/share/vm/code/relocInfo.cpp
index 0264f2060..7015dbc87 100644
--- a/src/share/vm/code/relocInfo.cpp
+++ b/src/share/vm/code/relocInfo.cpp
@@ -472,20 +472,14 @@ RelocationHolder Relocation::spec_simple(relocInfo::relocType rtype) {
   return itr._rh;
 }
 
-
-static inline bool is_index(intptr_t index) {
-  return 0 < index && index < os::vm_page_size();
-}
-
-
 int32_t Relocation::runtime_address_to_index(address runtime_address) {
-  assert(!is_index((intptr_t)runtime_address), "must not look like an index");
+  assert(!is_reloc_index((intptr_t)runtime_address), "must not look like an index");
 
   if (runtime_address == NULL)  return 0;
 
   StubCodeDesc* p = StubCodeDesc::desc_for(runtime_address);
   if (p != NULL && p->begin() == runtime_address) {
-    assert(is_index(p->index()), "there must not be too many stubs");
+    assert(is_reloc_index(p->index()), "there must not be too many stubs");
     return (int32_t)p->index();
   } else {
     // Known "miscellaneous" non-stub pointers:
@@ -506,7 +500,7 @@ int32_t Relocation::runtime_address_to_index(address runtime_address) {
 address Relocation::index_to_runtime_address(int32_t index) {
   if (index == 0)  return NULL;
 
-  if (is_index(index)) {
+  if (is_reloc_index(index)) {
     StubCodeDesc* p = StubCodeDesc::desc_for_index(index);
     assert(p != NULL, "there must be a stub for this index");
     return p->begin();
@@ -634,7 +628,7 @@ void external_word_Relocation::pack_data_to(CodeSection* dest) {
 #ifndef _LP64
   p = pack_1_int_to(p, index);
 #else
-  if (is_index(index)) {
+  if (is_reloc_index(index)) {
     p = pack_2_ints_to(p, index, 0);
   } else {
     jlong t = (jlong) _target;
@@ -642,7 +636,7 @@ void external_word_Relocation::pack_data_to(CodeSection* dest) {
     int32_t hi = high(t);
     p = pack_2_ints_to(p, lo, hi);
     DEBUG_ONLY(jlong t1 = jlong_from(hi, lo));
-    assert(!is_index(t1) && (address) t1 == _target, "not symmetric");
+    assert(!is_reloc_index(t1) && (address) t1 == _target, "not symmetric");
   }
 #endif /* _LP64 */
   dest->set_locs_end((relocInfo*) p);
@@ -656,7 +650,7 @@ void external_word_Relocation::unpack_data() {
   int32_t lo, hi;
   unpack_2_ints(lo, hi);
   jlong t = jlong_from(hi, lo);;
-  if (is_index(t)) {
+  if (is_reloc_index(t)) {
     _target = index_to_runtime_address(t);
   } else {
     _target = (address) t;
diff --git a/src/share/vm/code/relocInfo.hpp b/src/share/vm/code/relocInfo.hpp
index 7dc11fee0..013a4e61c 100644
--- a/src/share/vm/code/relocInfo.hpp
+++ b/src/share/vm/code/relocInfo.hpp
@@ -703,6 +703,10 @@ class Relocation VALUE_OBJ_CLASS_SPEC {
     assert(datalen()==0 || type()==relocInfo::none, "no data here");
   }
 
+  static bool is_reloc_index(intptr_t index) {
+    return 0 < index && index < os::vm_page_size();
+  }
+
  protected:
   // Helper functions for pack_data_to() and unpack_data().
 
@@ -1127,6 +1131,12 @@ class external_word_Relocation : public DataRelocation {
     return rh;
   }
 
+  // Some address looking values aren't safe to treat as relocations
+  // and should just be treated as constants.
+  static bool can_be_relocated(address target) {
+    return target != NULL && !is_reloc_index((intptr_t)target);
+  }
+
  private:
   address _target;                  // address in runtime
 
-- 
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