ARM: support arguments access in lithium-codegen-arm.

src/arm/lithium-codegen-arm.cc

Index: src/arm/lithium-codegen-arm.cc
===================================================================
--- src/arm/lithium-codegen-arm.cc	(revision 6178)
+++ src/arm/lithium-codegen-arm.cc	(working copy)
@@ -1588,7 +1588,18 @@
 
 
 void LCodeGen::DoAccessArgumentsAt(LAccessArgumentsAt* instr) {
-  Abort("DoAccessArgumentsAt unimplemented.");
+  Register arguments = ToRegister(instr->arguments());
+  Register length = ToRegister(instr->length());
+  Operand index = ToOperand(instr->index());
+  Register result = ToRegister(instr->result());
+
+  __ sub(length, length, index);
+  DeoptimizeIf(hi, instr->environment());
+
+  // There are two words between the frame pointer and the last argument.
+  // Subtracting from length accounts for one of them add one more.
+  __ add(length, length, Operand(1));
+  __ ldr(result, MemOperand(arguments, length, LSL, kPointerSizeLog2));
 }
 
 
@@ -1607,12 +1618,41 @@
 
 
 void LCodeGen::DoArgumentsElements(LArgumentsElements* instr) {
-  Abort("DoArgumentsElements unimplemented.");
+  Register scratch = scratch0();
+  Register result = ToRegister(instr->result());
+
+  // Check if the calling frame is an arguments adaptor frame.
+  Label done, adapted;
+  __ ldr(scratch, MemOperand(fp, StandardFrameConstants::kCallerFPOffset));
+  __ ldr(result, MemOperand(scratch, StandardFrameConstants::kContextOffset));
+  __ cmp(result, Operand(Smi::FromInt(StackFrame::ARGUMENTS_ADAPTOR)));
+
+  // Result is the frame pointer for the frame if not adapted and for the real
+  // frame below the adaptor frame if adapted.
+  __ mov(result, fp, LeaveCC, ne);
+  __ mov(result, scratch, LeaveCC, eq);
 }
 
 
 void LCodeGen::DoArgumentsLength(LArgumentsLength* instr) {
-  Abort("DoArgumentsLength unimplemented.");
+  Operand elem = ToOperand(instr->input());
+  Register result = ToRegister(instr->result());
+
+  Label done;
+
+  // If no arguments adaptor frame the number of arguments is fixed.
+  __ cmp(fp, elem);
+  __ mov(result, Operand(scope()->num_parameters()));
+  __ b(eq, &done);
+
+  // Arguments adaptor frame present. Get argument length from there.
+  __ ldr(result, MemOperand(fp, StandardFrameConstants::kCallerFPOffset));
+  __ ldr(result,
+         MemOperand(result, ArgumentsAdaptorFrameConstants::kLengthOffset));
+  __ SmiUntag(result);
+
+  // Argument length is in result register.
+  __ bind(&done);
 }