Changeset 37324 in webkit for trunk/JavaScriptCore/VM/CTI.cpp

Timestamp:

Oct 5, 2008, 11:00:58 PM (17 years ago)

Author:

[email protected]

Message:

2008-10-05 Cameron Zwarich <​[email protected]>

Reviewed by Oliver Hunt.

Bug 21364: Remove the branch in op_ret for OptionalCalleeActivation and OptionalCalleeArguments
<​https://bugs.webkit.org/show_bug.cgi?id=21364>

Use information from the parser to detect whether an activation is
needed or 'arguments' is used, and emit explicit instructions to tear
them off before op_ret. This allows a branch to be removed from op_ret
and simplifies some other code. This does cause a small change in the
behaviour of 'f.arguments'; it is no longer live when 'arguments' is not
mentioned in the lexical scope of the function.

It should now be easy to remove the OptionaCalleeActivation slot in the
call frame, but this will be done in a later patch.

JavaScriptCore:

• VM/CTI.cpp: (JSC::CTI::privateCompileMainPass):
• VM/CodeBlock.cpp: (JSC::CodeBlock::dump):
• VM/CodeGenerator.cpp: (JSC::CodeGenerator::emitReturn):
• VM/CodeGenerator.h:
• VM/Machine.cpp: (JSC::Machine::unwindCallFrame): (JSC::Machine::privateExecute): (JSC::Machine::retrieveArguments): (JSC::Machine::cti_op_create_arguments): (JSC::Machine::cti_op_tear_off_activation): (JSC::Machine::cti_op_tear_off_arguments):
• VM/Machine.h:
• VM/Opcode.h:
• kjs/Arguments.cpp: (JSC::Arguments::mark):
• kjs/Arguments.h: (JSC::Arguments::isTornOff): (JSC::Arguments::Arguments): (JSC::Arguments::copyRegisters): (JSC::JSActivation::copyRegisters):
• kjs/JSActivation.cpp: (JSC::JSActivation::argumentsGetter):
• kjs/JSActivation.h:

LayoutTests:

• fast/js/function-dot-arguments-expected.txt:
• fast/js/resources/function-dot-arguments.js:

File:

• trunk/JavaScriptCore/VM/CTI.cpp (modified) (2 diffs)

trunk/JavaScriptCore/VM/CTI.cpp

@@ -1171 +1171 @@
             break;
         }
+        case op_tear_off_activation: {
+            emitCall(i, Machine::cti_op_tear_off_activation);
+            i += 1;
+            break;
+        }
+        case op_tear_off_arguments: {
+            emitCall(i, Machine::cti_op_tear_off_arguments);
+            i += 1;
+            break;
+        }
         case op_ret: {
-            // If there is an activation or an 'arguments' object, we tear it
-            // off by jumping to the hook below.
-            m_jit.movl_mr(RegisterFile::OptionalCalleeActivation * static_cast<int>(sizeof(Register)), X86::edi, X86::eax);
-            m_jit.orl_mr(RegisterFile::OptionalCalleeArguments * static_cast<int>(sizeof(Register)), X86::edi, X86::eax);
-            m_jit.cmpl_i32r(0, X86::eax);
-            X86Assembler::JmpSrc activation = m_jit.emitUnlinkedJne();
-            X86Assembler::JmpDst activated = m_jit.label();
-
             // Check for a profiler - if there is one, jump to the hook below.
             emitGetCTIParam(CTI_ARGS_profilerReference, X86::eax);
@@ -1203 +1205 @@
             m_jit.pushl_r(X86::edx);
             m_jit.ret();
-
-            // Activation and 'arguments' hook
-            m_jit.link(activation, m_jit.label());
-            emitCall(i, Machine::cti_op_ret_activation_arguments);
-            m_jit.link(m_jit.emitUnlinkedJmp(), activated);
 
             // Profiling hook