Changeset 34777 in webkit for trunk/JavaScriptCore/VM/Machine.cpp

Timestamp:

Jun 24, 2008, 2:19:56 PM (17 years ago)

Author:

[email protected]

Message:

Groundwork for reimplementing the slow script dialog

Reviewed by Cameron.

Add special loop opcodes as groundwork for slow script
termination. Also added a few assertions to prevent us
from accidentally coalescing conditional jump operands
in a way that might bypass the slow script opcodes.

File:

• trunk/JavaScriptCore/VM/Machine.cpp (modified) (4 diffs)

trunk/JavaScriptCore/VM/Machine.cpp

@@ -896 +896 @@
     JSValue** k = codeBlock->jsValues.data();
     Profiler** enabledProfilerReference = Profiler::enabledProfilerReference();
-
+    
     registerFile->setSafeForReentry(false);
 #define VM_CHECK_EXCEPTION() \
@@ -909 +909 @@
     OpcodeStats::resetLastInstruction();
 #endif
-
+    
+#define CHECK_FOR_TIMEOUT() 
+    
 #if HAVE(COMPUTED_GOTO)
     #define NEXT_OPCODE goto *vPC->u.opcode
@@ -1888 +1890 @@
         NEXT_OPCODE;
     }
+    BEGIN_OPCODE(op_loop_if_true) {
+        /* loop_if_true cond(r) target(offset)
+         
+           Jumps to offset target from the current instruction, if and
+           only if register cond converts to boolean as true.
+
+           Additionally this loop instruction may terminate JS execution is
+           the JS timeout is reached.
+         */
+        int cond = (++vPC)->u.operand;
+        int target = (++vPC)->u.operand;
+        if (r[cond].u.jsValue->toBoolean(exec)) {
+            vPC += target;
+            CHECK_FOR_TIMEOUT();
+            NEXT_OPCODE;
+        }
+        
+        ++vPC;
+        NEXT_OPCODE;
+    }
     BEGIN_OPCODE(op_jtrue) {
         /* jtrue cond(r) target(offset)
@@ -1917 +1939 @@
         }
 
+        ++vPC;
+        NEXT_OPCODE;
+    }
+    BEGIN_OPCODE(op_loop_if_less) {
+        /* loop_if_less src1(r) src2(r) target(offset)
+
+           Checks whether register src1 is less than register src2, as
+           with the ECMAScript '<' operator, and then jumps to offset
+           target from the current instruction, if and only if the 
+           result of the comparison is true.
+
+           Additionally this loop instruction may terminate JS execution is
+           the JS timeout is reached.
+         */
+        JSValue* src1 = r[(++vPC)->u.operand].u.jsValue;
+        JSValue* src2 = r[(++vPC)->u.operand].u.jsValue;
+        int target = (++vPC)->u.operand;
+        
+        bool result = jsLess(exec, src1, src2);
+        VM_CHECK_EXCEPTION();
+        
+        if (result) {
+            vPC += target;
+            CHECK_FOR_TIMEOUT();
+            NEXT_OPCODE;
+        }
+        
         ++vPC;
         NEXT_OPCODE;