Changeset 183072 in webkit for trunk/Source/JavaScriptCore/dfg/DFGDCEPhase.cpp

Timestamp:

Apr 21, 2015, 1:16:18 PM (10 years ago)

Author:

[email protected]

Message:

MovHint should be a strong use
​https://bugs.webkit.org/show_bug.cgi?id=143734

Reviewed by Geoffrey Garen.

This disables any DCE that assumes equivalence between DFG IR uses and bytecode uses. Doing
so is a major step towards allowing more fancy DFG transformations and also probably fixing
some bugs.

Just making MovHint a strong use would also completely disable DCE. So we mitigate this by
introducing a MovHint removal phase that runs in FTL.

This is a slight slowdown on Octane/gbemu, but it's basically neutral on suite averages.

• CMakeLists.txt:
• JavaScriptCore.vcxproj/JavaScriptCore.vcxproj:
• JavaScriptCore.xcodeproj/project.pbxproj:
• bytecode/CodeOrigin.cpp:

(JSC::InlineCallFrame::dumpInContext):

• dfg/DFGDCEPhase.cpp:

(JSC::DFG::DCEPhase::fixupBlock):

• dfg/DFGDisassembler.cpp:

(JSC::DFG::Disassembler::createDumpList):

• dfg/DFGEpoch.cpp: Added.

(JSC::DFG::Epoch::dump):

• dfg/DFGEpoch.h: Added.

(JSC::DFG::Epoch::Epoch):
(JSC::DFG::Epoch::first):
(JSC::DFG::Epoch::operator!):
(JSC::DFG::Epoch::next):
(JSC::DFG::Epoch::bump):
(JSC::DFG::Epoch::operator==):
(JSC::DFG::Epoch::operator!=):

• dfg/DFGMayExit.cpp:

(JSC::DFG::mayExit):

• dfg/DFGMovHintRemovalPhase.cpp: Added.

(JSC::DFG::performMovHintRemoval):

• dfg/DFGMovHintRemovalPhase.h: Added.
• dfg/DFGNodeType.h:
• dfg/DFGPlan.cpp:

(JSC::DFG::Plan::compileInThreadImpl):

• dfg/DFGSpeculativeJIT.cpp:

(JSC::DFG::SpeculativeJIT::compileCurrentBlock):

• dfg/DFGSpeculativeJIT64.cpp:

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

• runtime/Options.h:

File:

• trunk/Source/JavaScriptCore/dfg/DFGDCEPhase.cpp (modified) (1 diff)

trunk/Source/JavaScriptCore/dfg/DFGDCEPhase.cpp

@@ -144 +144 @@
                 
             switch (node->op()) {
-            case MovHint: {
-                // Check if the child is dead. MovHint's child would only be a Phantom or
-                // Check if we had just killed it.
-                if (node->child1()->op() == Phantom || node->child1()->op() == Check) {
-                    node->setOpAndDefaultFlags(ZombieHint);
-                    node->child1() = Edge();
-                    break;
-                }
-                break;
-            }
-                
-            case ZombieHint: {
-                // Currently we assume that DCE runs only once.
+            case MovHint:
+            case ZombieHint:
+                // These are not killable. (They once were.)
                 RELEASE_ASSERT_NOT_REACHED();
-                break;
-            }
-            
+                
             default: {
                 if (node->flags() & NodeHasVarArgs) {