Changeset 262570 in webkit for trunk/Source/JavaScriptCore/ftl/FTLOSRExitCompiler.cpp

Timestamp:

Jun 4, 2020, 2:07:42 PM (5 years ago)

Author:

[email protected]

Message:

Add Options::validateDoesGC() for turning DoesGC validation on/off.
​https://bugs.webkit.org/show_bug.cgi?id=212773

Reviewed by Saam Barati.

It will default to on if ASSERT_ENABLED because we want testing to be done with
the validation on. When needed, we can turn it off if we need to e.g. to
de-clutter disassembly dumps while debugging.

If Options::validateDoesGC() is false, we turn off JIT code emission for this
check, as well as skip the validation checks. There are still places in C++
code that store to DoesGC::m_value without checking Options::validateDoesGC().
It doesn't hurt to just let these stores proceed, and performance-wise, it's
probably cheaper to just do the store unconditionally than to gate it on a load of
Options::validateDoesGC() first.

Also made it explicit that the check on validateDFGDoesGC is a constexpr check.

• dfg/DFGDoesGCCheck.cpp:

(JSC::DFG::DoesGCCheck::verifyCanGC):

• dfg/DFGOSRExit.cpp:

(JSC::DFG::OSRExit::compileExit):

• dfg/DFGSpeculativeJIT32_64.cpp:

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

• dfg/DFGSpeculativeJIT64.cpp:

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

• ftl/FTLLowerDFGToB3.cpp:

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

• ftl/FTLOSRExitCompiler.cpp:

(JSC::FTL::compileStub):

• runtime/OptionsList.h:

File:

• trunk/Source/JavaScriptCore/ftl/FTLOSRExitCompiler.cpp (modified) (2 diffs)

trunk/Source/JavaScriptCore/ftl/FTLOSRExitCompiler.cpp

@@ -207 +207 @@
     saveAllRegisters(jit, registerScratch);
     
-    if (validateDFGDoesGC) {
-        // We're about to exit optimized code. So, there's no longer any optimized
-        // code running that expects no GC. We need to set this before object
-        // materialization below.
-
-        // Even though we set Heap::m_doesGC in compileFTLOSRExit(), we also need
-        // to set it here because compileFTLOSRExit() is only called on the first time
-        // we exit from this site, but all subsequent exits will take this compiled
-        // ramp without calling compileFTLOSRExit() first.
-        jit.store32(CCallHelpers::TrustedImm32(DoesGCCheck::encode(true, DoesGCCheck::Special::FTLOSRExit)), vm.heap.addressOfDoesGC());
+    if constexpr (validateDFGDoesGC) {
+        if (Options::validateDoesGC()) {
+            // We're about to exit optimized code. So, there's no longer any optimized
+            // code running that expects no GC. We need to set this before object
+            // materialization below.
+
+            // Even though we set Heap::m_doesGC in compileFTLOSRExit(), we also need
+            // to set it here because compileFTLOSRExit() is only called on the first time
+            // we exit from this site, but all subsequent exits will take this compiled
+            // ramp without calling compileFTLOSRExit() first.
+            jit.store32(CCallHelpers::TrustedImm32(DoesGCCheck::encode(true, DoesGCCheck::Special::FTLOSRExit)), vm.heap.addressOfDoesGC());
+        }
     }
 
@@ -546 +548 @@
     VM& vm = callFrame->deprecatedVM();
 
-    if (validateDFGDoesGC) {
+    if constexpr (validateDFGDoesGC) {
         // We're about to exit optimized code. So, there's no longer any optimized
         // code running that expects no GC.