Fix x64 patching of asllocation stub: the pool pointer must be set-up before patching jump is execu…

runtime/vm/stub_code_x64.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/assembler.h"
 #include "vm/compiler.h"
 #include "vm/dart_entry.h"
@@ skipping 1049 matching lines @@
   __ CallRuntime(kStoreBufferBlockProcessRuntimeEntry, 1);
   __ LeaveCallRuntimeFrame();
   __ ret();
 }
 
 
 // Called for inline allocation of objects.
 // Input parameters:
 //   RSP + 8 : type arguments object (only if class is parameterized).
 //   RSP : points to return address.
-uword StubCode::GenerateAllocationStubForClass(Assembler* assembler,
-                                              const Class& cls) {
+void StubCode::GenerateAllocationStubForClass(
+    Assembler* assembler, const Class& cls,
+    uword* entry_patch_offset, uword* patch_code_pc_offset) {
+  // Must set-up a PP before being able to patch.
+  Register new_pp = R13;
+  Register new_pc = R12;
+
+  Label next;
+  __ nop(4);  // Need a fixed size sequence on frame entry.
+  __ call(&next);
+  __ Bind(&next);
+
+  const intptr_t object_pool_pc_dist =
+      Instructions::HeaderSize() - Instructions::object_pool_offset() +
+      __ CodeSize();
+  const intptr_t offset =
+      Assembler::EntryPointToPcMarkerOffset() - __ CodeSize();
+  __ popq(new_pc);
+  if (offset != 0) {
+    __ addq(new_pc, Immediate(offset));
+  }
+
+  // Load pool pointer.
+  __ movq(new_pp, Address(new_pc, -object_pool_pc_dist - offset));
+  *entry_patch_offset = assembler->CodeSize();

[zra, 2014/09/16 20:55:58]

Since this is a delicate bit of code, I'd recommend adding a function to the x64
assembler instead of duplicating from EmitFrameEntry. (It also appears in the
else-if case in EmitFrameEntry, but duplicating there is possibly not as bad
since they're right next to each other).

[srdjan, 2014/09/16 21:54:50]

Good suggestion! Done.

+
   const intptr_t kObjectTypeArgumentsOffset = 1 * kWordSize;
   // The generated code is different if the class is parameterized.
   const bool is_cls_parameterized = cls.NumTypeArguments() > 0;
   ASSERT(!is_cls_parameterized ||
          (cls.type_arguments_field_offset() != Class::kNoTypeArguments));
   // kInlineInstanceSize is a constant used as a threshold for determining
   // when the object initialization should be done as a loop or as
   // straight line code.
   const int kInlineInstanceSize = 12;  // In words.
   const intptr_t instance_size = cls.instance_size();
@@ skipping 91 matching lines @@
     __ pushq(R12);  // Push null type arguments.
   }
   __ CallRuntime(kAllocateObjectRuntimeEntry, 2);  // Allocate object.
   __ popq(RAX);  // Pop argument (type arguments of object).
   __ popq(RAX);  // Pop argument (class of object).
   __ popq(RAX);  // Pop result (newly allocated object).
   // RAX: new object
   // Restore the frame pointer.
   __ LeaveStubFrame();
   __ ret();
-  uword patch_code_pc_offset = assembler->CodeSize();
+  *patch_code_pc_offset = assembler->CodeSize();
   StubCode* stub_code = Isolate::Current()->stub_code();
-  __ JmpPatchable(&stub_code->FixAllocationStubTargetLabel(), R13);
-  return patch_code_pc_offset;
+  __ JmpPatchable(&stub_code->FixAllocationStubTargetLabel(), new_pp);
 }
 
 
 // Called for invoking "dynamic noSuchMethod(Invocation invocation)" function
 // from the entry code of a dart function after an error in passed argument
 // name or number is detected.
 // Input parameters:
 //   RSP : points to return address.
 //   RSP + 8 : address of last argument.
 //   R10 : arguments descriptor array.
@@ skipping 825 matching lines @@
 
   __ movq(left, Address(RSP, 2 * kWordSize));
   __ movq(right, Address(RSP, 1 * kWordSize));
   GenerateIdenticalWithNumberCheckStub(assembler, left, right);
   __ ret();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64