commit e3c0b54b3f653eb9000116ec1fa18349e0f1ed9c
author buzbee <buzbee@google.com> Thu Apr 07 15:22:06 2011 -0700
committer buzbee <buzbee@google.com> Fri Apr 08 17:39:45 2011 -0700
tree f3c8f89266773c5705a46235027659a6eba17864
parent f1b531793e65fda22818d8dca8b17f94f618ad64

[JIT] Fix volatile test

On SMP systems, Dalvik opcodes referencing volatile fields will be
rewritten to their _VOLATILE variant.  On non-SMP systems, though,
this rewriting is not done.  The JIT, however, needs to know about
volatility for all systems in order to avoid performing unsafe
optimizations.  This change fixes the JIT's volatility test to be
either _VOLATILE opcode or the volatile flag in the field access bits
depending on SMP type.

Change-Id: I2edde58dc25f22cba88f62c5f1a2d125473309e6

vm/compiler/codegen/arm/CodegenDriver.c

diff --git a/vm/compiler/codegen/arm/CodegenDriver.c b/vm/compiler/codegen/arm/CodegenDriver.c
index e4c4536..6060ab7 100644
--- a/vm/compiler/codegen/arm/CodegenDriver.c
+++ b/vm/compiler/codegen/arm/CodegenDriver.c
@@ -1637,7 +1637,6 @@
                 mir->meta.calleeMethod : cUnit->method;
             void *fieldPtr = (void*)
               (method->clazz->pDvmDex->pResFields[mir->dalvikInsn.vB]);
-            Opcode opcode = mir->dalvikInsn.opcode;
 
             if (fieldPtr == NULL) {
                 BAIL_LOOP_COMPILATION();
@@ -1645,12 +1644,24 @@
                 dvmAbort();
             }
 
+            /*
+             * On SMP systems, Dalvik opcodes found to be referencing
+             * volatile fields are rewritten to their _VOLATILE variant.
+             * However, this does not happen on non-SMP systems. The JIT
+             * still needs to know about volatility to avoid unsafe
+             * optimizations so we determine volatility based on either
+             * the opcode or the field access flags.
+             */
+#if ANDROID_SMP != 0
+            Opcode opcode = mir->dalvikInsn.opcode;
             isVolatile = (opcode == OP_SGET_VOLATILE) ||
                          (opcode == OP_SGET_VOLATILE_JUMBO) ||
                          (opcode == OP_SGET_OBJECT_VOLATILE) ||
                          (opcode == OP_SGET_OBJECT_VOLATILE_JUMBO);
-
             assert(isVolatile == dvmIsVolatileField((Field *) fieldPtr));
+#else
+            isVolatile = dvmIsVolatileField((Field *) fieldPtr);
+#endif
 
             rlDest = dvmCompilerGetDest(cUnit, mir, 0);
             rlResult = dvmCompilerEvalLoc(cUnit, rlDest, kAnyReg, true);
@@ -1725,12 +1736,15 @@
                 dvmAbort();
             }
 
+#if ANDROID_SMP != 0
             isVolatile = (opcode == OP_SPUT_VOLATILE) ||
                          (opcode == OP_SPUT_VOLATILE_JUMBO) ||
                          (opcode == OP_SPUT_OBJECT_VOLATILE) ||
                          (opcode == OP_SPUT_OBJECT_VOLATILE_JUMBO);
-
             assert(isVolatile == dvmIsVolatileField((Field *) fieldPtr));
+#else
+            isVolatile = dvmIsVolatileField((Field *) fieldPtr);
+#endif
 
             isSputObject = (opcode == OP_SPUT_OBJECT) ||
                            (opcode == OP_SPUT_OBJECT_JUMBO) ||
@@ -2410,8 +2424,10 @@
         case OP_IPUT_VOLATILE_JUMBO:
         case OP_IPUT_OBJECT_VOLATILE:
         case OP_IPUT_OBJECT_VOLATILE_JUMBO:
+#if ANDROID_SMP != 0
             isVolatile = true;
         // NOTE: intentional fallthrough
+#endif
         case OP_IGET:
         case OP_IGET_JUMBO:
         case OP_IGET_WIDE:
@@ -2450,7 +2466,12 @@
                 LOGE("Unexpected null instance field");
                 dvmAbort();
             }
-            assert(isVolatile == dvmIsVolatileField(fieldPtr));
+
+#if ANDROID_SMP != 0
+            assert(isVolatile == dvmIsVolatileField((Field *) fieldPtr));
+#else
+            isVolatile = dvmIsVolatileField((Field *) fieldPtr);
+#endif
             fieldOffset = ((InstField *)fieldPtr)->byteOffset;
             break;
         }
@@ -2559,8 +2580,6 @@
         case OP_IGET_VOLATILE_JUMBO:
         case OP_IGET_OBJECT_VOLATILE:
         case OP_IGET_OBJECT_VOLATILE_JUMBO:
-            isVolatile = true;
-            // NOTE: intentional fallthrough
         case OP_IGET:
         case OP_IGET_JUMBO:
         case OP_IGET_OBJECT:
@@ -2581,8 +2600,6 @@
             break;
         case OP_IPUT_VOLATILE:
         case OP_IPUT_VOLATILE_JUMBO:
-            isVolatile = true;
-            // NOTE: intentional fallthrough
         case OP_IPUT:
         case OP_IPUT_JUMBO:
         case OP_IPUT_BOOLEAN:
@@ -2597,8 +2614,6 @@
             break;
         case OP_IPUT_OBJECT_VOLATILE:
         case OP_IPUT_OBJECT_VOLATILE_JUMBO:
-            isVolatile = true;
-            // NOTE: intentional fallthrough
         case OP_IPUT_OBJECT:
         case OP_IPUT_OBJECT_JUMBO:
             genIPut(cUnit, mir, kWord, fieldOffset, true, isVolatile);