Reviewed by Oliver Hunt.

Presently the JIT and the interpreter have differing implementations in how
they handle storing the result of a function call back to the register file.
In both cases the op_call ( / _eval / _varargs / op_construct) opcode has an
operand indicating the VM register in which the result should be stored.
The JIT plants code after the call to store the result, so the value will be
stored as soon as the callee has returned.  In the interpreter the call
passes the return value register id into the callee via the callee callframe,
and the callee is responsible for writing the result back into its callers
register file after it has restored the parents callframe pointer, but before
returning.

Instead, move the task of writing the call result to the register file into a
new opcode (op_call_put_result), and after returning the callee should leave
the return value in a canonical location.  In the case of the interpreter,
this canonical location is a local variable in privateExecute
(functionReturnValue), in the case of the JIT this is the normal return value
registers (regT0, or regT1:regT0 in JSVALUE32_64).  op_call_put_result stores
the result from the canonical location to the registerfile.

In addition to unifying JIT & interpreter behaviour this change allows us to
remove a slot from the callframe, omit the write of the result where the
return value from the call is not used, and provides a 2% speedup on sunspider
in the interpreter.

* bytecode/CodeBlock.cpp:
(JSC::CodeBlock::dump):
* bytecode/Opcode.h:
* bytecompiler/BytecodeGenerator.cpp:
(JSC::BytecodeGenerator::emitCall):
(JSC::BytecodeGenerator::emitCallVarargs):
(JSC::BytecodeGenerator::emitConstruct):
* bytecompiler/BytecodeGenerator.h:
(JSC::BytecodeGenerator::finalDestinationOrIgnored):
* bytecompiler/NodesCodegen.cpp:
(JSC::NewExprNode::emitBytecode):
(JSC::FunctionCallValueNode::emitBytecode):
(JSC::FunctionCallResolveNode::emitBytecode):
(JSC::FunctionCallBracketNode::emitBytecode):
(JSC::FunctionCallDotNode::emitBytecode):
(JSC::CallFunctionCallDotNode::emitBytecode):
(JSC::ApplyFunctionCallDotNode::emitBytecode):
* interpreter/CallFrame.h:
(JSC::ExecState::init):
(JSC::ExecState::noCaller):
* interpreter/Interpreter.cpp:
(JSC::Interpreter::dumpRegisters):
(JSC::Interpreter::throwException):
(JSC::Interpreter::privateExecute):
* interpreter/RegisterFile.h:
(JSC::RegisterFile::):
* jit/JIT.cpp:
(JSC::JIT::privateCompileMainPass):
* jit/JIT.h:
* jit/JITCall.cpp:
(JSC::JIT::compileOpCallSetupArgs):
(JSC::JIT::compileOpConstructSetupArgs):
(JSC::JIT::emit_op_call_put_result):
(JSC::JIT::compileOpCallVarargs):
(JSC::JIT::compileOpCallVarargsSlowCase):
(JSC::JIT::compileOpCall):
(JSC::JIT::compileOpCallSlowCase):
(JSC::JIT::compileOpCallVarargsSetupArgs):



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@59860 268f45cc-cd09-0410-ab3c-d52691b4dbfc