Changeset 153263 in webkit for trunk/Source/JavaScriptCore/jit/JITOpcodes.cpp

Timestamp:

Jul 24, 2013, 9:04:18 PM (12 years ago)

Author:

[email protected]

Message:

fourthTier: add option to disable OSR entry in loops
​https://bugs.webkit.org/show_bug.cgi?id=118329

Reviewed by Mark Hahnenberg.

This adds that option, and also makes the OSR exit reoptimization trigger rely less on
OSR entry failing. Now even if we never attempt OSR entry but our execution counter gets
high after a small number of OSR exits, we will recompile.

• dfg/DFGOSRExitCompilerCommon.cpp:

(JSC::DFG::handleExitCounts):

• dfg/DFGOperations.cpp:
• jit/JITOpcodes.cpp:

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

• runtime/Options.h:

(JSC):

File:

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

trunk/Source/JavaScriptCore/jit/JITOpcodes.cpp

@@ -1150 +1150 @@
 {
     // Emit the JIT optimization check: 
-    if (canBeOptimized())
-        addSlowCase(branchAdd32(PositiveOrZero, TrustedImm32(Options::executionCounterIncrementForLoop()),
-            AbsoluteAddress(m_codeBlock->addressOfJITExecuteCounter())));
+    if (canBeOptimized()) {
+        if (Options::enableOSREntryInLoops()) {
+            addSlowCase(branchAdd32(PositiveOrZero, TrustedImm32(Options::executionCounterIncrementForLoop()),
+                AbsoluteAddress(m_codeBlock->addressOfJITExecuteCounter())));
+        } else {
+            // Add with saturation.
+            move(TrustedImmPtr(m_codeBlock->addressOfJITExecuteCounter()), regT3);
+            load32(regT3, regT2);
+            Jump dontAdd = branch32(
+                GreaterThan, regT2,
+                TrustedImm32(std::numeric_limits<int32_t>::max() - Options::executionCounterIncrementForLoop()));
+            add32(TrustedImm32(Options::executionCounterIncrementForLoop()), regT2);
+            store32(regT2, regT3);
+            dontAdd.link(this);
+        }
+    }
 
     // Emit the watchdog timer check:
@@ -1163 +1176 @@
 #if ENABLE(DFG_JIT)
     // Emit the slow path for the JIT optimization check:
-    if (canBeOptimized()) {
+    if (canBeOptimized() && Options::enableOSREntryInLoops()) {
         linkSlowCase(iter);
-
+        
         JITStubCall stubCall(this, cti_optimize);
         stubCall.addArgument(TrustedImm32(m_bytecodeOffset));
         stubCall.call();
-
+        
         emitJumpSlowToHot(jump(), OPCODE_LENGTH(op_loop_hint));
     }