Changeset 148989 in webkit for trunk/Source/JavaScriptCore/jit

Timestamp:

Apr 23, 2013, 1:54:34 PM (12 years ago)

Author:

[email protected]

Message:

Simplify the baseline JIT loop hint call site.
​https://bugs.webkit.org/show_bug.cgi?id=115052.

Reviewed by Geoffrey Garen.

Moved the watchdog timer check after the JIT optimization check. This
ensures that the JIT opimization counter is incremented on every loop
hint even if the watchdog timer fires.

Removed the code that allows the JIT OSR to happen if the watchdog
timer fires but does not result in a termination. It is extremely rare
that the JIT optimization counter would trigger an OSR on the same pass
as when the watchdog timer fire. If it does happen, we'll simply hold
off on servicing the watchdog timer until the next pass (because it's
not time critical).

• jit/JITOpcodes.cpp:

(JSC::JIT::emit_op_loop_hint):
(JSC::JIT::emitSlow_op_loop_hint):

File:

• trunk/Source/JavaScriptCore/jit/JITOpcodes.cpp (modified) (2 diffs)

trunk/Source/JavaScriptCore/jit/JITOpcodes.cpp

@@ -1280 +1280 @@
 void JIT::emit_op_loop_hint(Instruction*)
 {
-    // Emit the watchdog timer check:
-    if (m_vm->watchdog.isEnabled())
-        addSlowCase(branchTest8(NonZero, AbsoluteAddress(m_vm->watchdog.timerDidFireAddress())));
-
     // Emit the JIT optimization check: 
     if (canBeOptimized())
         addSlowCase(branchAdd32(PositiveOrZero, TrustedImm32(Options::executionCounterIncrementForLoop()),
             AbsoluteAddress(m_codeBlock->addressOfJITExecuteCounter())));
+
+    // Emit the watchdog timer check:
+    if (m_vm->watchdog.isEnabled())
+        addSlowCase(branchTest8(NonZero, AbsoluteAddress(m_vm->watchdog.timerDidFireAddress())));
 }
 
 void JIT::emitSlow_op_loop_hint(Instruction*, Vector<SlowCaseEntry>::iterator& iter)
 {
-    // Emit the slow path of the watchdog timer check:
-    if (m_vm->watchdog.isEnabled()) {
-        linkSlowCase(iter);
-
-        JITStubCall stubCall(this, cti_handle_watchdog_timer);
-        stubCall.call();
-
-#if ENABLE(DFG_JIT)
-        if (canBeOptimized()) {
-            Jump doOptimize = branchAdd32(PositiveOrZero, TrustedImm32(Options::executionCounterIncrementForLoop()),
-                AbsoluteAddress(m_codeBlock->addressOfJITExecuteCounter()));
-            emitJumpSlowToHot(jump(), OPCODE_LENGTH(op_loop_hint));
-            doOptimize.link(this);
-        } else
-#endif
-            emitJumpSlowToHot(jump(), OPCODE_LENGTH(op_loop_hint));
-    }
-
 #if ENABLE(DFG_JIT)
     // Emit the slow path for the JIT optimization check:
@@ -1322 +1304 @@
     }
 #endif
+
+    // Emit the slow path of the watchdog timer check:
+    if (m_vm->watchdog.isEnabled()) {
+        linkSlowCase(iter);
+
+        JITStubCall stubCall(this, cti_handle_watchdog_timer);
+        stubCall.call();
+
+        emitJumpSlowToHot(jump(), OPCODE_LENGTH(op_loop_hint));
+    }
+
 }