8257513: C2: assert((constant_addr - _masm.code()->consts()->start()) == con.offset())

Reviewed-by: kvn, thartmann

src/hotspot/share/opto/constantTable.cpp

@@ -114,7 +114,7 @@ void ConstantTable::calculate_offsets_and_size() {
   _size = align_up(offset, (int)CodeEntryAlignment);
 }
 
-void ConstantTable::emit(CodeBuffer& cb) {
+bool ConstantTable::emit(CodeBuffer& cb) const {
   MacroAssembler _masm(&cb);
   for (int i = 0; i < _constants.length(); i++) {
     Constant con = _constants.at(i);
@@ -143,12 +143,30 @@ void ConstantTable::emit(CodeBuffer& cb) {
       // filled in later in fill_jump_table.
       address dummy = (address) n;
       constant_addr = _masm.address_constant(dummy);
-      // Expand jump-table
-      for (uint i = 1; i < n->outcnt(); i++) {
-        address temp_addr = _masm.address_constant(dummy + i);
-        assert(temp_addr, "consts section too small");
+      if (constant_addr == NULL) {
+        return false;
       }
-      break;
+      assert((constant_addr - _masm.code()->consts()->start()) == con.offset(),
+             "must be: %d == %d", (int)(constant_addr - _masm.code()->consts()->start()), (int)(con.offset()));
+
+      // Expand jump-table
+      address last_addr;
+      for (uint j = 1; j < n->outcnt(); j++) {
+        last_addr = _masm.address_constant(dummy + j);
+        if (last_addr == NULL) {
+          return false;
+        }
+      }
+#ifdef ASSERT
+      address start = _masm.code()->consts()->start();
+      address new_constant_addr = last_addr - ((n->outcnt() - 1) * sizeof(address));
+      // Expanding the jump-table could result in an expansion of the const code section.
+      // In that case, we need to check if the new constant address matches the offset.
+      assert((constant_addr - start == con.offset()) || (new_constant_addr - start == con.offset()),
+             "must be: %d == %d or %d == %d (after an expansion)", (int)(constant_addr - start), (int)(con.offset()),
+             (int)(new_constant_addr - start), (int)(con.offset()));
+#endif
+      continue; // Loop
     }
     case T_METADATA: {
       Metadata* obj = con.get_metadata();
@@ -158,10 +176,14 @@ void ConstantTable::emit(CodeBuffer& cb) {
     }
     default: ShouldNotReachHere();
     }
-    assert(constant_addr, "consts section too small");
+
+    if (constant_addr == NULL) {
+      return false;
+    }
     assert((constant_addr - _masm.code()->consts()->start()) == con.offset(),
-            "must be: %d == %d", (int) (constant_addr - _masm.code()->consts()->start()), (int)(con.offset()));
+            "must be: %d == %d", (int)(constant_addr - _masm.code()->consts()->start()), (int)(con.offset()));
   }
+  return true;
 }
 
 int ConstantTable::find_offset(Constant& con) const {

src/hotspot/share/opto/constantTable.hpp

@@ -113,7 +113,7 @@ public:
   void set_table_base_offset(int x)  { assert(_table_base_offset == -1 || x == _table_base_offset, "can't change"); _table_base_offset = x; }
   int      table_base_offset() const { assert(_table_base_offset != -1, "not set yet");                      return _table_base_offset; }
 
-  void emit(CodeBuffer& cb);
+  bool emit(CodeBuffer& cb) const;
 
   // Returns the offset of the last entry (the top) of the constant table.
   int  top_offset() const { assert(_constants.top().offset() != -1, "not bound yet"); return _constants.top().offset(); }

src/hotspot/share/opto/output.cpp

@@ -1425,7 +1425,10 @@ void PhaseOutput::fill_buffer(CodeBuffer* cb, uint* blk_starts) {
 
   // Emit the constant table.
   if (C->has_mach_constant_base_node()) {
-    constant_table().emit(*cb);
+    if (!constant_table().emit(*cb)) {
+      C->record_failure("consts section overflow");
+      return;
+    }
   }
 
   // Create an array of labels, one for each basic block

test/hotspot/jtreg/compiler/codecache/TestStressCodeBuffers.java

@@ -0,0 +1,57 @@
+/*
+ * Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug 8257513
+ * @requires vm.debug == true
+ * @summary Stress testing code buffers resulted in an assertion failure due to not taking expand calls into account
+ *          which can fail more often with -XX:+StressCodeBuffers. Perform some more sanity flag testing.
+ * @run main/othervm -Xcomp -XX:-TieredCompilation -XX:+StressCodeBuffers compiler.codecache.TestStressCodeBuffers
+ * @run main/othervm -Xcomp -XX:+StressCodeBuffers compiler.codecache.TestStressCodeBuffers
+ */
+
+package compiler.codecache;
+
+import java.lang.invoke.MethodHandle;
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.MethodType;
+
+public class TestStressCodeBuffers {
+
+    static MethodHandle permh;
+
+    public static void main(String[] args) throws Exception {
+        test();
+    }
+
+    public static void test() throws Exception {
+        MethodHandles.Lookup lookup = MethodHandles.publicLookup();
+        MethodHandle mh = lookup.findStatic(TestStressCodeBuffers.class, "bar",
+                                            MethodType.methodType(void.class, int.class, long.class));
+        permh = MethodHandles.permuteArguments(mh, mh.type(), 0, 1); // Triggers assertion failure
+    }
+
+    public static void bar(int x, long y) {}
+}
+