Disassembler: Fix support for non-commutative symbolic operators.

Care must be taken when disassembling operators like subtract and shift left. The operators cannot be interchanged, so there are additional restrictions on when these operators can be converted to a compound assignment. David Box.
acpica · May 29, 2015 · 5bc9437 · 5bc9437 · RehabMan · May 29, 2015
1 parent 6005294
commit 5bc9437
Showing 1 changed file with 61 additions and 14 deletions.
diff --git a/source/components/disassembler/dmcstyle.c b/source/components/disassembler/dmcstyle.c
@@ -409,23 +409,70 @@ AcpiDmCheckForSymbolicOpcode (
          */
         AcpiDmPromoteTarget (Op, Target);
 
-        /*
-         * Check for possible conversion to a "Compound Assignment".
-         *
-         * Determine if either operand is the same as the target
-         * and display compound assignment operator and other operand.
-         */
-        if ((AcpiDmIsTargetAnOperand (Target, Child1, TRUE)) ||
-            (AcpiDmIsTargetAnOperand (Target, Child2, TRUE)))
+        /* Check operands for conversion to a "Compound Assignment" */
+
+        switch (Op->Common.AmlOpcode)
         {
-            Target->Common.OperatorSymbol =
-                AcpiDmGetCompoundSymbol (Op->Common.AmlOpcode);
+            /* Commutative operators */
 
-            /* Convert operator to compound assignment */
+        case AML_ADD_OP:
+        case AML_MULTIPLY_OP:
+        case AML_BIT_AND_OP:
+        case AML_BIT_OR_OP:
+        case AML_BIT_XOR_OP:
+            /*
+             * For the commutative operators, we can convert to a
+             * compound statement only if at least one (either) operand
+             * is the same as the target.
+             *
+             *      Add (A, B, A) --> A += B
+             *      Add (B, A, A) --> A += B
+             *      Add (B, C, A) --> A = (B + C)
+             */
+            if ((AcpiDmIsTargetAnOperand (Target, Child1, TRUE)) ||
+                (AcpiDmIsTargetAnOperand (Target, Child2, TRUE)))
+            {
+                Target->Common.OperatorSymbol =
+                    AcpiDmGetCompoundSymbol (Op->Common.AmlOpcode);
 
-            Op->Common.DisasmFlags |= ACPI_PARSEOP_COMPOUND;
-            Child1->Common.OperatorSymbol = NULL;
-            return (TRUE);
+                /* Convert operator to compound assignment */
+
+                Op->Common.DisasmFlags |= ACPI_PARSEOP_COMPOUND;
+                Child1->Common.OperatorSymbol = NULL;
+                return (TRUE);
+            }
+            break;
+
+            /* Non-commutative operators */
+
+        case AML_SUBTRACT_OP:
+        case AML_DIVIDE_OP:
+        case AML_MOD_OP:
+        case AML_SHIFT_LEFT_OP:
+        case AML_SHIFT_RIGHT_OP:
+            /*
+             * For the non-commutative operators, we can convert to a
+             * compound statement only if the target is the same as the
+             * first operand.
+             *
+             *      Subtract (A, B, A) --> A -= B
+             *      Subtract (B, A, A) --> A = (B - A)
+             */
+            if ((AcpiDmIsTargetAnOperand (Target, Child1, TRUE)))
+            {
+                Target->Common.OperatorSymbol =
+                    AcpiDmGetCompoundSymbol (Op->Common.AmlOpcode);
+
+                /* Convert operator to compound assignment */
+
+                Op->Common.DisasmFlags |= ACPI_PARSEOP_COMPOUND;
+                Child1->Common.OperatorSymbol = NULL;
+                return (TRUE);
+            }
+            break;
+
+        default:
+            break;
         }
 
         /*