Changeset 267062 in webkit for trunk/Source/JavaScriptCore/dfg/DFGByteCodeParser.cpp

Timestamp:

Sep 14, 2020, 6:25:54 PM (5 years ago)

Author:

[email protected]

Message:

BytecodeParser should GetLocal op_ret's value even if it's unused by the caller
​https://bugs.webkit.org/show_bug.cgi?id=216506

Reviewed by Mark Lam.

JSTests:

• stress/osr-availability-should-see-unused-return-as-available.js: Added.

(foo):
(set isFinite):

Source/JavaScriptCore:

We have to unconditionally GetLocal operands each bytecode claims to use
regardless of true liveness. This is important to keep OSRAvailability simple.
However, op_ret would only GetLocal the return value if we knew the value
was going to be used by an inline caller.

• dfg/DFGByteCodeParser.cpp:

(JSC::DFG::ByteCodeParser::parseBlock):

File:

• trunk/Source/JavaScriptCore/dfg/DFGByteCodeParser.cpp (modified) (2 diffs)

trunk/Source/JavaScriptCore/dfg/DFGByteCodeParser.cpp

@@ -6521 +6521 @@
             auto bytecode = currentInstruction->as<OpRet>();
             ASSERT(!m_currentBlock->terminal());
+            // We have to get the return here even if we know the caller won't use it because the GetLocal may
+            // be the only thing keeping m_value alive for OSR.
+            auto returnValue = get(bytecode.m_value);
+
             if (!inlineCallFrame()) {
                 // Simple case: we are just producing a return
-                addToGraph(Return, get(bytecode.m_value));
+                addToGraph(Return, returnValue);
                 flushForReturn();
                 LAST_OPCODE(op_ret);
@@ -6530 +6534 @@
             flushForReturn();
             if (m_inlineStackTop->m_returnValue.isValid())
-                setDirect(m_inlineStackTop->m_returnValue, get(bytecode.m_value), ImmediateSetWithFlush);
+                setDirect(m_inlineStackTop->m_returnValue, returnValue, ImmediateSetWithFlush);
 
             if (!m_inlineStackTop->m_continuationBlock && m_currentIndex.offset() + currentInstruction->size() != m_inlineStackTop->m_codeBlock->instructions().size()) {