Changeset 213302 in webkit

Timestamp:

Mar 2, 2017 2:06:04 PM (7 years ago)

Author:

mark.lam@apple.com

Message:

Add Options::alwaysCheckTraps() and Options::usePollingTraps() options.
​https://bugs.webkit.org/show_bug.cgi?id=169088

Reviewed by Keith Miller.

Options::alwaysCheckTraps() forces the op_check_traps bytecode to always be
generated. This is useful for testing purposes until we have signal based
traps, at which point, we will always emit the op_check_traps bytecode and remove
this option.

Options::usePollingTraps() enables the use of polling VM traps all the time.
This will be useful for benchmark comparisons, (between polling and non-polling
traps), as well as for forcing polling traps later for ports that don't support
signal based traps.

Note: signal based traps are not fully implemented yet. As a result, if the VM
watchdog is in use, we will force Options::usePollingTraps() to be true.

• bytecompiler/BytecodeGenerator.cpp:

(JSC::BytecodeGenerator::emitCheckTraps):

• dfg/DFGClobberize.h:

(JSC::DFG::clobberize):

• dfg/DFGSpeculativeJIT.cpp:

(JSC::DFG::SpeculativeJIT::compileCheckTraps):

• dfg/DFGSpeculativeJIT32_64.cpp:

(JSC::DFG::SpeculativeJIT::compile):

• dfg/DFGSpeculativeJIT64.cpp:

(JSC::DFG::SpeculativeJIT::compile):

• ftl/FTLLowerDFGToB3.cpp:

(JSC::FTL::DFG::LowerDFGToB3::compileNode):
(JSC::FTL::DFG::LowerDFGToB3::compileCheckTraps):

• runtime/Options.cpp:

(JSC::recomputeDependentOptions):

• runtime/Options.h:

Location:

trunk/Source/JavaScriptCore

Files:

• ChangeLog (modified) (1 diff)
• bytecompiler/BytecodeGenerator.cpp (modified) (1 diff)
• dfg/DFGClobberize.h (modified) (2 diffs)
• dfg/DFGSpeculativeJIT.cpp (modified) (1 diff)
• dfg/DFGSpeculativeJIT32_64.cpp (modified) (1 diff)
• dfg/DFGSpeculativeJIT64.cpp (modified) (1 diff)
• ftl/FTLLowerDFGToB3.cpp (modified) (2 diffs)
• runtime/Options.h (modified) (1 diff)
• runtime/VM.cpp (modified) (2 diffs)
• runtime/VM.h (modified) (1 diff)

trunk/Source/JavaScriptCore/ChangeLog

@@ +1 @@
+2017-03-02  Mark Lam  <mark.lam@apple.com>
+
+        Add Options::alwaysCheckTraps() and Options::usePollingTraps() options.
+        https://bugs.webkit.org/show_bug.cgi?id=169088
+
+        Reviewed by Keith Miller.
+
+        Options::alwaysCheckTraps() forces the op_check_traps bytecode to always be
+        generated.  This is useful for testing purposes until we have signal based
+        traps, at which point, we will always emit the op_check_traps bytecode and remove
+        this option.
+
+        Options::usePollingTraps() enables the use of polling VM traps all the time.
+        This will be useful for benchmark comparisons, (between polling and non-polling
+        traps), as well as for forcing polling traps later for ports that don't support
+        signal based traps.
+
+        Note: signal based traps are not fully implemented yet.  As a result, if the VM
+        watchdog is in use, we will force Options::usePollingTraps() to be true.
+
+        * bytecompiler/BytecodeGenerator.cpp:
+        (JSC::BytecodeGenerator::emitCheckTraps):
+        * dfg/DFGClobberize.h:
+        (JSC::DFG::clobberize):
+        * dfg/DFGSpeculativeJIT.cpp:
+        (JSC::DFG::SpeculativeJIT::compileCheckTraps):
+        * dfg/DFGSpeculativeJIT32_64.cpp:
+        (JSC::DFG::SpeculativeJIT::compile):
+        * dfg/DFGSpeculativeJIT64.cpp:
+        (JSC::DFG::SpeculativeJIT::compile):
+        * ftl/FTLLowerDFGToB3.cpp:
+        (JSC::FTL::DFG::LowerDFGToB3::compileNode):
+        (JSC::FTL::DFG::LowerDFGToB3::compileCheckTraps):
+        * runtime/Options.cpp:
+        (JSC::recomputeDependentOptions):
+        * runtime/Options.h:
+
 2017-03-02  Keith Miller  <keith_miller@apple.com>
 

trunk/Source/JavaScriptCore/bytecompiler/BytecodeGenerator.cpp

@@ -1275 +1275 @@
 void BytecodeGenerator::emitCheckTraps()
 {
-    if (vm()->watchdog() || vm()->needAsynchronousTerminationSupport())
+    if (Options::alwaysCheckTraps() || vm()->watchdog() || vm()->needAsynchronousTerminationSupport())
         emitOpcode(op_check_traps);
 }

trunk/Source/JavaScriptCore/dfg/DFGClobberize.h

@@ -435 +435 @@
         return;
 
+    case CheckTraps:
+        if (Options::usePollingTraps()) {
+            read(InternalState);
+            write(InternalState);
+        } else
+            write(Watchpoint_fire);
+        return;
+
     case InvalidationPoint:
         write(SideState);
@@ -1412 +1420 @@
         
     case CountExecution:
-    case CheckTraps:
         read(InternalState);
         write(InternalState);

trunk/Source/JavaScriptCore/dfg/DFGSpeculativeJIT.cpp

@@ -1899 +1899 @@
 void SpeculativeJIT::compileCheckTraps(Node*)
 {
+    ASSERT(Options::usePollingTraps());
     GPRTemporary unused(this);
     GPRReg unusedGPR = unused.gpr();

trunk/Source/JavaScriptCore/dfg/DFGSpeculativeJIT32_64.cpp

@@ -5545 +5545 @@
 
     case CheckTraps:
-        compileCheckTraps(node);
+        if (Options::usePollingTraps())
+            compileCheckTraps(node);
+        else
+            noResult(node); // This is a no-op.
         break;
 

trunk/Source/JavaScriptCore/dfg/DFGSpeculativeJIT64.cpp

@@ -5329 +5329 @@
 
     case CheckTraps:
-        compileCheckTraps(node);
+        if (Options::usePollingTraps())
+            compileCheckTraps(node);
+        else
+            noResult(node); // This is a no-op.
         break;
 

trunk/Source/JavaScriptCore/ftl/FTLLowerDFGToB3.cpp

@@ -1024 +1024 @@
             break;
         case CheckTraps:
-            compileCheckTraps();
+            if (Options::usePollingTraps())
+                compileCheckTraps();
             break;
         case CreateRest:
@@ -8987 +8988 @@
     void compileCheckTraps()
     {
+        ASSERT(Options::usePollingTraps());
         LBasicBlock needTrapHandling = m_out.newBlock();
         LBasicBlock continuation = m_out.newBlock();

trunk/Source/JavaScriptCore/runtime/Options.h

@@ -407 +407 @@
     \
     v(unsigned, watchdog, 0, Normal, "watchdog timeout (0 = Disabled, N = a timeout period of N milliseconds)") \
+    v(bool, alwaysCheckTraps, false, Normal, "always emit op_check_traps bytecode") \
+    v(bool, usePollingTraps, false, Normal, "use polling (instead of signalling) VM traps") \
     \
     v(bool, useICStats, false, Normal, nullptr) \

trunk/Source/JavaScriptCore/runtime/VM.cpp

@@ -463 +463 @@
 {
     if (!m_watchdog) {
+        Options::usePollingTraps() = true; // Force polling traps on until we have support for signal based traps.
+
         m_watchdog = adoptRef(new Watchdog(this));
         
@@ -974 +976 @@
 }
 
+void VM::setNeedAsynchronousTerminationSupport()
+{
+    Options::usePollingTraps() = true; // Force polling traps on until we have support for signal based traps.
+    m_needAsynchronousTerminationSupport = true;
+}
+
 } // namespace JSC

trunk/Source/JavaScriptCore/runtime/VM.h

@@ -681 +681 @@
 
     bool needAsynchronousTerminationSupport() const { return m_needAsynchronousTerminationSupport; }
-    void setNeedAsynchronousTerminationSupport() { m_needAsynchronousTerminationSupport = true; }
+    JS_EXPORT_PRIVATE void setNeedAsynchronousTerminationSupport();
 
 private: