commit c061de1236e98fdd34d0214a9bbcc0e2149ff226
author Alexey Frunze <Alexey.Frunze@imgtec.com> Tue Feb 14 13:27:23 2017 -0800
committer Alexey Frunze <Alexey.Frunze@imgtec.com> Wed Feb 22 14:10:59 2017 -0800
tree 31f6644cf080613d8493db8f510810a89cc6a718
parent 4c9c57054578022d9ab8442264fbc661769f97f5

MIPS: Implement heap poisoning in ART's Optimizing compiler.

This is in preparation for read barrier support.

Bug: 12687968

Test: test-art-host-gtest
Test: booted MIPS32R2 in QEMU
Test: test-art-target
Test: booted MIPS64 (with 2nd arch MIPS32R6) in QEMU
Test: test-art-target (both MIPS64R6 and MIPS32R6)

Note: built with ART_HEAP_POISONING=true.

Change-Id: I0e6e04ff8de2fc8ca6126388409fa218e6920734

compiler/utils/mips/assembler_mips.cc

diff --git a/compiler/utils/mips/assembler_mips.cc b/compiler/utils/mips/assembler_mips.cc
index 5e83e82..2e2231b 100644
--- a/compiler/utils/mips/assembler_mips.cc
+++ b/compiler/utils/mips/assembler_mips.cc
@@ -3475,8 +3475,8 @@
   CHECK(dest.IsCoreRegister() && base.AsMips().IsCoreRegister());
   LoadFromOffset(kLoadWord, dest.AsCoreRegister(),
                  base.AsMips().AsCoreRegister(), offs.Int32Value());
-  if (kPoisonHeapReferences && unpoison_reference) {
-    Subu(dest.AsCoreRegister(), ZERO, dest.AsCoreRegister());
+  if (unpoison_reference) {
+    MaybeUnpoisonHeapReference(dest.AsCoreRegister());
   }
 }
 

compiler/utils/mips/assembler_mips.h

diff --git a/compiler/utils/mips/assembler_mips.h b/compiler/utils/mips/assembler_mips.h
index 2fca185..47ddf25 100644
--- a/compiler/utils/mips/assembler_mips.h
+++ b/compiler/utils/mips/assembler_mips.h
@@ -727,6 +727,38 @@
   void Pop(Register rd);
   void PopAndReturn(Register rd, Register rt);
 
+  //
+  // Heap poisoning.
+  //
+
+  // Poison a heap reference contained in `src` and store it in `dst`.
+  void PoisonHeapReference(Register dst, Register src) {
+    // dst = -src.
+    Subu(dst, ZERO, src);
+  }
+  // Poison a heap reference contained in `reg`.
+  void PoisonHeapReference(Register reg) {
+    // reg = -reg.
+    PoisonHeapReference(reg, reg);
+  }
+  // Unpoison a heap reference contained in `reg`.
+  void UnpoisonHeapReference(Register reg) {
+    // reg = -reg.
+    Subu(reg, ZERO, reg);
+  }
+  // Poison a heap reference contained in `reg` if heap poisoning is enabled.
+  void MaybePoisonHeapReference(Register reg) {
+    if (kPoisonHeapReferences) {
+      PoisonHeapReference(reg);
+    }
+  }
+  // Unpoison a heap reference contained in `reg` if heap poisoning is enabled.
+  void MaybeUnpoisonHeapReference(Register reg) {
+    if (kPoisonHeapReferences) {
+      UnpoisonHeapReference(reg);
+    }
+  }
+
   void Bind(Label* label) OVERRIDE {
     Bind(down_cast<MipsLabel*>(label));
   }