Changeset 37125 in webkit for trunk/JavaScriptCore/VM/Machine.cpp

Timestamp:

Sep 30, 2008, 4:46:29 PM (17 years ago)

Author:

Darin Adler

Message:

2008-09-30 Darin Adler <Darin Adler>

Reviewed by Geoff Garen.

• ​https://bugs.webkit.org/show_bug.cgi?id=21214 work on getting rid of ExecState

Replaced the m_prev field of ExecState with a bit in the
call frame pointer to indicate "host" call frames.

• VM/Machine.cpp: (JSC::makeHostCallFramePointer): Added. Sets low bit. (JSC::isHostCallFrame): Added. Checks low bit. (JSC::stripHostCallFrameBit): Added. Clears low bit. (JSC::Machine::unwindCallFrame): Replaced null check that was formerly used to detect host call frames with an isHostCallFrame check. (JSC::Machine::execute): Pass in a host call frame pointer rather than always passing 0 when starting execution from the host. This allows us to follow the entire call frame pointer chain when desired, or to stop at the host calls when that's desired. (JSC::Machine::privateExecute): Replaced null check that was formerly used to detect host call frames with an isHostCallFrame check. (JSC::Machine::retrieveCaller): Ditto. (JSC::Machine::retrieveLastCaller): Ditto. (JSC::Machine::callFrame): Removed the code to walk up m_prev pointers and replaced it with code that uses the caller pointer and uses the stripHostCallFrameBit function.

• kjs/ExecState.cpp: Removed m_prev.
• kjs/ExecState.h: Ditto.

File:

• trunk/JavaScriptCore/VM/Machine.cpp (modified) (9 diffs)

trunk/JavaScriptCore/VM/Machine.cpp

@@ -106 +106 @@
 #endif // #ENABLE(CTI)
 
+static const intptr_t HostCallFrameMask = 1;
+
+static inline Register* makeHostCallFramePointer(Register* callFrame)
+{
+    return reinterpret_cast<Register*>(reinterpret_cast<intptr_t>(callFrame) | HostCallFrameMask);
+}
+
+static inline bool isHostCallFrame(Register* callFrame)
+{
+    return reinterpret_cast<intptr_t>(callFrame) & HostCallFrameMask;
+}
+
+static inline Register* stripHostCallFrameBit(Register* callFrame)
+{
+    return reinterpret_cast<Register*>(reinterpret_cast<intptr_t>(callFrame) & ~HostCallFrameMask);
+}
+
 // Returns the depth of the scope chain within a given call frame.
 static int depth(CodeBlock* codeBlock, ScopeChain& sc)
@@ -793 +810 @@
     void* returnPC = r[RegisterFile::ReturnPC].v();
     r = r[RegisterFile::CallerRegisters].r();
-    if (!r)
+    if (isHostCallFrame(r))
         return false;
 
@@ -897 +914 @@
     Register* r = m_registerFile.base() + oldSize + codeBlock->numParameters + RegisterFile::CallFrameHeaderSize;
     r[codeBlock->thisRegister] = thisObj;
-    initializeCallFrame(r, codeBlock, 0, scopeChain, 0, 0, 0, 0);
+    initializeCallFrame(r, codeBlock, 0, scopeChain, makeHostCallFramePointer(0), 0, 0, 0);
 
     if (codeBlock->needsFullScopeChain)
@@ -962 +979 @@
     }
     // a 0 codeBlock indicates a built-in caller
-    initializeCallFrame(r, codeBlock, 0, scopeChain, 0, 0, argc, function);
+    initializeCallFrame(r, codeBlock, 0, scopeChain, makeHostCallFramePointer(exec->m_callFrame), 0, argc, function);
 
     ExecState newExec(exec, r);
@@ -1045 +1062 @@
     // a 0 codeBlock indicates a built-in caller
     r[codeBlock->thisRegister] = thisObj;
-    initializeCallFrame(r, codeBlock, 0, scopeChain, 0, 0, 0, 0);
+    initializeCallFrame(r, codeBlock, 0, scopeChain, makeHostCallFramePointer(exec->m_callFrame), 0, 0, 0);
 
     if (codeBlock->needsFullScopeChain)
@@ -3363 +3380 @@
         exec->m_callFrame = r;
         
-        if (!r)
+        if (isHostCallFrame(r))
             return returnValue;
 
@@ -3854 +3871 @@
 
     Register* callerR = r[RegisterFile::CallerRegisters].r();
-    if (!callerR)
+    if (isHostCallFrame(callerR))
         return jsNull();
 
@@ -3872 +3889 @@
     Register* r = exec->m_callFrame;
     Register* callerR = r[RegisterFile::CallerRegisters].r();
-    if (!callerR)
+    if (isHostCallFrame(callerR))
         return;
 
@@ -3893 +3910 @@
 Register* Machine::callFrame(ExecState* exec, InternalFunction* function) const
 {
-    for (; exec; exec = exec->m_prev)
-        for (Register* r = exec->m_callFrame; r; r = r[RegisterFile::CallerRegisters].r())
-            if (r[RegisterFile::Callee].jsValue(exec) == function)
-                return r;
-                
+    for (Register* r = exec->m_callFrame; r; r = stripHostCallFrameBit(r[RegisterFile::CallerRegisters].r()))
+        if (r[RegisterFile::Callee].getJSValue() == function)
+            return r;
     return 0;
 }