Changeset 202862 in webkit for trunk/Source/JavaScriptCore/interpreter/JSStack.cpp

Timestamp:

Jul 6, 2016, 10:19:20 AM (9 years ago)

Author:

[email protected]

Message:

Rename VM stack limit fields to better describe their purpose.
​https://bugs.webkit.org/show_bug.cgi?id=159451

Reviewed by Keith Miller.

This is in preparation for an upcoming patch that changes what stack limit values
are used under various circumstances. This patch aims to do some minimal work to
rename the fields so that it will be easier to reason about the upcoming patch.

In this patch, we make the following changes:

1. Rename VM::m_stackLimit to VM::m_jsCPUStackLimit.

2. VM::m_jsStackLimit used to have an overloaded meaning:
   1. For JIT builds, m_jsStackLimit is synonymous with m_stackLimit.
   2. For C Loop builds, m_jsStackLimit is a separate pointer that points to the emulated JS stack that the C Loop uses.

In place of m_jsStackLimit, this patch introduces 2 new fields:
VM::m_jsEmulatedStackLimit and VM::m_llintStackLimit.

m_llintStackLimit is the limit that the LLInt assembly uses for its stack
check. m_llintStackLimit behaves like the old m_jsStackLimit in that:

1. For JIT builds, m_llintStackLimit is synonymous with m_jsCPUStackLimit.
2. For C Loop builds, m_llintStackLimit is synonymous with m_jsEmulatedStackLimit.

m_jsEmulatedStackLimit is used for the emulated stack that the C Loop uses.

3. Rename the following methods to match the above:

VM::stackLimit() ==> VM::jsCPUStackLimit()
VM::addressOfStackLimit() ==> VM::addressOfJSCPUStackLimit()
VM::jsStackLimit() ==> VM::jsEmulatedStackLimit()
VM::setJSStackLimit() ==> VM::setJSEmulatedStackLimit()
JSStack::setStackLimit() ==> JSStack::setEmulatedStackLimit()

4. With change (2) and (3), the limits will be used as follows:
   1. VM code doing stack recursion checks will only use m_jsCPUStackLimit.
   2. JIT code will only use m_jsCPUStackLimit.
   3. C Loop emulated stack code in JSStack will only use m_jsEmulatedStackLimit. Note: the part of JSStack that operates on a JIT build will use

m_jsCPUStackLimit as expected.

4. LLINT assembly code will only use m_llintStackLimit.

This patch only contains the above refactoring changes. There is no behavior
change.

• dfg/DFGJITCompiler.cpp:

(JSC::DFG::JITCompiler::compile):
(JSC::DFG::JITCompiler::compileFunction):

• ftl/FTLLowerDFGToB3.cpp:

(JSC::FTL::DFG::LowerDFGToB3::lower):

• interpreter/JSStack.cpp:

(JSC::JSStack::JSStack):
(JSC::JSStack::growSlowCase):
(JSC::JSStack::lowAddress):
(JSC::JSStack::highAddress):

• interpreter/JSStack.h:
• interpreter/JSStackInlines.h:

(JSC::JSStack::ensureCapacityFor):
(JSC::JSStack::shrink):
(JSC::JSStack::grow):
(JSC::JSStack::setJSEmulatedStackLimit):
(JSC::JSStack::setStackLimit): Deleted.

• jit/JIT.cpp:

(JSC::JIT::compileWithoutLinking):

• jit/SetupVarargsFrame.cpp:

(JSC::emitSetupVarargsFrameFastCase):

• llint/LLIntSlowPaths.cpp:

(JSC::LLInt::LLINT_SLOW_PATH_DECL):

• llint/LowLevelInterpreter.asm:
• llint/LowLevelInterpreter32_64.asm:
• llint/LowLevelInterpreter64.asm:
• runtime/RegExp.cpp:

(JSC::RegExp::finishCreation):
(JSC::RegExp::compile):
(JSC::RegExp::compileMatchOnly):

• runtime/VM.cpp:

(JSC::VM::VM):
(JSC::VM::updateStackLimit):

• runtime/VM.h:

(JSC::VM::reservedZoneSize):
(JSC::VM::jsCPUStackLimit):
(JSC::VM::addressOfJSCPUStackLimit):
(JSC::VM::jsEmulatedStackLimit):
(JSC::VM::setJSEmulatedStackLimit):
(JSC::VM::isSafeToRecurse):
(JSC::VM::jsStackLimit): Deleted.
(JSC::VM::setJSStackLimit): Deleted.
(JSC::VM::stackLimit): Deleted.
(JSC::VM::addressOfStackLimit): Deleted.

• wasm/WASMFunctionCompiler.h:

(JSC::WASMFunctionCompiler::startFunction):

File:

• trunk/Source/JavaScriptCore/interpreter/JSStack.cpp (modified) (5 diffs)

trunk/Source/JavaScriptCore/interpreter/JSStack.cpp

@@ -1 +1 @@
 /*
- * Copyright (C) 2008, 2013, 2014, 2015 Apple Inc. All rights reserved.
+ * Copyright (C) 2008, 2013-2016 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -63 +63 @@
 
     m_reservation = PageReservation::reserve(WTF::roundUpToMultipleOf(commitSize(), capacity), OSAllocator::JSVMStackPages);
-    setStackLimit(highAddress());
+    setJSEmulatedStackLimit(highAddress());
     m_commitTop = highAddress();
     
@@ -88 +88 @@
     // just update the end pointer and return.
     if (newTopOfStackWithReservedZone >= m_commitTop) {
-        setStackLimit(newTopOfStack);
+        setJSEmulatedStackLimit(newTopOfStack);
         return true;
     }
@@ -105 +105 @@
     addToCommittedByteCount(delta);
     m_commitTop = newCommitTop;
-    setStackLimit(newTopOfStack);
+    setJSEmulatedStackLimit(newTopOfStack);
     return true;
 }
@@ -157 +157 @@
 {
     ASSERT(wtfThreadData().stack().isGrowingDownward());
-    return reinterpret_cast<Register*>(m_vm.stackLimit());
+    return reinterpret_cast<Register*>(m_vm.jsCPUStackLimit());
 }