Merge 6168:6800 from bleeding_edge to experimental/gc branch.

src/ia32/macro-assembler-ia32.cc

Index: src/ia32/macro-assembler-ia32.cc
===================================================================
--- src/ia32/macro-assembler-ia32.cc	(revision 6800)
+++ src/ia32/macro-assembler-ia32.cc	(working copy)
@@ -1,4 +1,4 @@
-// Copyright 2010 the V8 project authors. All rights reserved.
+// Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
@@ -86,11 +86,6 @@
                                  Register value,
                                  Register scratch,
                                  SaveFPRegsMode save_fp) {
-  // The compiled code assumes that record write doesn't change the
-  // context register, so we check that none of the clobbered
-  // registers are esi.
-  ASSERT(!object.is(esi) && !value.is(esi) && !scratch.is(esi));
-
   // First, check if a write barrier is even needed. The tests below
   // catch stores of Smis and stores into young gen.
   NearLabel done;
@@ -138,11 +133,6 @@
                                  Register address,
                                  Register value,
                                  SaveFPRegsMode save_fp) {
-  // The compiled code assumes that record write doesn't change the
-  // context register, so we check that none of the clobbered
-  // registers are esi.
-  ASSERT(!object.is(esi) && !value.is(esi) && !address.is(esi));
-
   // First, check if a write barrier is even needed. The tests below
   // catch stores of Smis and stores into young gen.
   Label done;
@@ -348,7 +338,7 @@
     CpuFeatures::Scope scope(SSE2);
     int space = XMMRegister::kNumRegisters * kDoubleSize + argc * kPointerSize;
     sub(Operand(esp), Immediate(space));
-    int offset = -2 * kPointerSize;
+    const int offset = -2 * kPointerSize;
     for (int i = 0; i < XMMRegister::kNumRegisters; i++) {
       XMMRegister reg = XMMRegister::from_code(i);
       movdbl(Operand(ebp, offset - ((i + 1) * kDoubleSize)), reg);
@@ -391,22 +381,10 @@
   // Optionally restore all XMM registers.
   if (save_doubles) {
     CpuFeatures::Scope scope(SSE2);
-    if (save_doubles) {
-      int offset = -2 * kPointerSize;
-      for (int i = 0; i < XMMRegister::kNumRegisters; i++) {
-        XMMRegister reg = XMMRegister::from_code(i);
-        movdbl(reg, Operand(ebp, offset - ((i + 1) * kDoubleSize)));
-      }
-    } else if (FLAG_debug_code) {
-      // Zap all fp registers on a runtime call if we were not asked to preserve
-      // them.
-      push(eax);
-      mov(eax, Factory::nan_value());
-      for (int i = 0; i < XMMRegister::kNumRegisters; i++) {
-        XMMRegister reg = XMMRegister::from_code(i);
-        movdbl(reg, FieldOperand(eax, HeapNumber::kValueOffset));
-      }
-      pop(eax);
+    const int offset = -2 * kPointerSize;
+    for (int i = 0; i < XMMRegister::kNumRegisters; i++) {
+      XMMRegister reg = XMMRegister::from_code(i);
+      movdbl(reg, Operand(ebp, offset - ((i + 1) * kDoubleSize)));
     }
   }
 
@@ -479,6 +457,97 @@
 }
 
 
+void MacroAssembler::Throw(Register value) {
+  // Adjust this code if not the case.
+  STATIC_ASSERT(StackHandlerConstants::kSize == 4 * kPointerSize);
+
+  // eax must hold the exception.
+  if (!value.is(eax)) {
+    mov(eax, value);
+  }
+
+  // Drop the sp to the top of the handler.
+  ExternalReference handler_address(Top::k_handler_address);
+  mov(esp, Operand::StaticVariable(handler_address));
+
+  // Restore next handler and frame pointer, discard handler state.
+  STATIC_ASSERT(StackHandlerConstants::kNextOffset == 0);
+  pop(Operand::StaticVariable(handler_address));
+  STATIC_ASSERT(StackHandlerConstants::kFPOffset == 1 * kPointerSize);
+  pop(ebp);
+  pop(edx);  // Remove state.
+
+  // Before returning we restore the context from the frame pointer if
+  // not NULL.  The frame pointer is NULL in the exception handler of
+  // a JS entry frame.
+  Set(esi, Immediate(0));  // Tentatively set context pointer to NULL.
+  NearLabel skip;
+  cmp(ebp, 0);
+  j(equal, &skip, not_taken);
+  mov(esi, Operand(ebp, StandardFrameConstants::kContextOffset));
+  bind(&skip);
+
+  STATIC_ASSERT(StackHandlerConstants::kPCOffset == 3 * kPointerSize);
+  ret(0);
+}
+
+
+void MacroAssembler::ThrowUncatchable(UncatchableExceptionType type,
+                                      Register value) {
+  // Adjust this code if not the case.
+  STATIC_ASSERT(StackHandlerConstants::kSize == 4 * kPointerSize);
+
+  // eax must hold the exception.
+  if (!value.is(eax)) {
+    mov(eax, value);
+  }
+
+  // Drop sp to the top stack handler.
+  ExternalReference handler_address(Top::k_handler_address);
+  mov(esp, Operand::StaticVariable(handler_address));
+
+  // Unwind the handlers until the ENTRY handler is found.
+  NearLabel loop, done;
+  bind(&loop);
+  // Load the type of the current stack handler.
+  const int kStateOffset = StackHandlerConstants::kStateOffset;
+  cmp(Operand(esp, kStateOffset), Immediate(StackHandler::ENTRY));
+  j(equal, &done);
+  // Fetch the next handler in the list.
+  const int kNextOffset = StackHandlerConstants::kNextOffset;
+  mov(esp, Operand(esp, kNextOffset));
+  jmp(&loop);
+  bind(&done);
+
+  // Set the top handler address to next handler past the current ENTRY handler.
+  STATIC_ASSERT(StackHandlerConstants::kNextOffset == 0);
+  pop(Operand::StaticVariable(handler_address));
+
+  if (type == OUT_OF_MEMORY) {
+    // Set external caught exception to false.
+    ExternalReference external_caught(Top::k_external_caught_exception_address);
+    mov(eax, false);
+    mov(Operand::StaticVariable(external_caught), eax);
+
+    // Set pending exception and eax to out of memory exception.
+    ExternalReference pending_exception(Top::k_pending_exception_address);
+    mov(eax, reinterpret_cast<int32_t>(Failure::OutOfMemoryException()));
+    mov(Operand::StaticVariable(pending_exception), eax);
+  }
+
+  // Clear the context pointer.
+  Set(esi, Immediate(0));
+
+  // Restore fp from handler and discard handler state.
+  STATIC_ASSERT(StackHandlerConstants::kFPOffset == 1 * kPointerSize);
+  pop(ebp);
+  pop(edx);  // State.
+
+  STATIC_ASSERT(StackHandlerConstants::kPCOffset == 3 * kPointerSize);
+  ret(0);
+}
+
+
 void MacroAssembler::CheckAccessGlobalProxy(Register holder_reg,
                                             Register scratch,
                                             Label* miss) {
@@ -625,11 +694,11 @@
   ExternalReference new_space_allocation_limit =
       ExternalReference::new_space_allocation_limit_address();
 
-  if (top_reg.is(result)) {
-    add(Operand(top_reg), Immediate(object_size));
-  } else {
-    lea(top_reg, Operand(result, object_size));
+  if (!top_reg.is(result)) {
+    mov(top_reg, result);
   }
+  add(Operand(top_reg), Immediate(object_size));
+  j(carry, gc_required, not_taken);
   cmp(top_reg, Operand::StaticVariable(new_space_allocation_limit));
   j(above, gc_required, not_taken);
 
@@ -678,7 +747,12 @@
   // Calculate new top and bail out if new space is exhausted.
   ExternalReference new_space_allocation_limit =
       ExternalReference::new_space_allocation_limit_address();
-  lea(result_end, Operand(result, element_count, element_size, header_size));
+
+  // We assume that element_count*element_size + header_size does not
+  // overflow.
+  lea(result_end, Operand(element_count, element_size, header_size));
+  add(result_end, Operand(result));
+  j(carry, gc_required);
   cmp(result_end, Operand::StaticVariable(new_space_allocation_limit));
   j(above, gc_required);
 
@@ -723,6 +797,7 @@
     mov(result_end, object_size);
   }
   add(result_end, Operand(result));
+  j(carry, gc_required, not_taken);
   cmp(result_end, Operand::StaticVariable(new_space_allocation_limit));
   j(above, gc_required, not_taken);
 
@@ -898,55 +973,53 @@
       Immediate(Factory::cons_ascii_string_map()));
 }
 
-// All registers must be distinct.  Only current_string needs valid contents
-// on entry.  All registers may be invalid on exit.  result_operand is
-// unchanged, padding_chars is updated correctly.
-void MacroAssembler::AppendStringToTopOfNewSpace(
-    Register current_string,  // Tagged pointer to string to copy.
-    Register current_string_length,
-    Register result_pos,
-    Register scratch,
-    Register new_padding_chars,
-    Operand operand_result,
-    Operand operand_padding_chars,
-    Label* bailout) {
-  mov(current_string_length,
-      FieldOperand(current_string, String::kLengthOffset));
-  shr(current_string_length, 1);
-  sub(current_string_length, operand_padding_chars);
-  mov(new_padding_chars, current_string_length);
-  add(Operand(current_string_length), Immediate(kObjectAlignmentMask));
-  and_(Operand(current_string_length), Immediate(~kObjectAlignmentMask));
-  sub(new_padding_chars, Operand(current_string_length));
-  neg(new_padding_chars);
-  // We need an allocation even if current_string_length is 0, to fetch
-  // result_pos.  Consider using a faster fetch of result_pos in that case.
-  AllocateInNewSpace(current_string_length, result_pos, scratch, no_reg,
-                     bailout, NO_ALLOCATION_FLAGS);
-  sub(result_pos, operand_padding_chars);
-  mov(operand_padding_chars, new_padding_chars);
 
-  Register scratch_2 = new_padding_chars;  // Used to compute total length.
-  // Copy string to the end of result.
-  mov(current_string_length,
-      FieldOperand(current_string, String::kLengthOffset));
-  mov(scratch, operand_result);
-  mov(scratch_2, current_string_length);
-  add(scratch_2, FieldOperand(scratch, String::kLengthOffset));
-  mov(FieldOperand(scratch, String::kLengthOffset), scratch_2);
-  shr(current_string_length, 1);
-  lea(current_string,
-      FieldOperand(current_string, SeqAsciiString::kHeaderSize));
-  // Loop condition: while (--current_string_length >= 0).
-  Label copy_loop;
-  Label copy_loop_entry;
-  jmp(&copy_loop_entry);
-  bind(&copy_loop);
-  mov_b(scratch, Operand(current_string, current_string_length, times_1, 0));
-  mov_b(Operand(result_pos, current_string_length, times_1, 0), scratch);
-  bind(&copy_loop_entry);
-  sub(Operand(current_string_length), Immediate(1));
-  j(greater_equal, &copy_loop);
+// Copy memory, byte-by-byte, from source to destination.  Not optimized for
+// long or aligned copies.  The contents of scratch and length are destroyed.
+// Source and destination are incremented by length.
+// Many variants of movsb, loop unrolling, word moves, and indexed operands
+// have been tried here already, and this is fastest.
+// A simpler loop is faster on small copies, but 30% slower on large ones.
+// The cld() instruction must have been emitted, to set the direction flag(),
+// before calling this function.
+void MacroAssembler::CopyBytes(Register source,
+                               Register destination,
+                               Register length,
+                               Register scratch) {
+  Label loop, done, short_string, short_loop;
+  // Experimentation shows that the short string loop is faster if length < 10.
+  cmp(Operand(length), Immediate(10));
+  j(less_equal, &short_string);
+
+  ASSERT(source.is(esi));
+  ASSERT(destination.is(edi));
+  ASSERT(length.is(ecx));
+
+  // Because source is 4-byte aligned in our uses of this function,
+  // we keep source aligned for the rep_movs call by copying the odd bytes
+  // at the end of the ranges.
+  mov(scratch, Operand(source, length, times_1, -4));
+  mov(Operand(destination, length, times_1, -4), scratch);
+  mov(scratch, ecx);
+  shr(ecx, 2);
+  rep_movs();
+  and_(Operand(scratch), Immediate(0x3));
+  add(destination, Operand(scratch));
+  jmp(&done);
+
+  bind(&short_string);
+  test(length, Operand(length));
+  j(zero, &done);
+
+  bind(&short_loop);
+  mov_b(scratch, Operand(source, 0));
+  mov_b(Operand(destination, 0), scratch);
+  inc(source);
+  inc(destination);
+  dec(length);
+  j(not_zero, &short_loop);
+
+  bind(&done);
 }
 
 
@@ -1310,7 +1383,7 @@
   ExternalReference scheduled_exception_address =
       ExternalReference::scheduled_exception_address();
   cmp(Operand::StaticVariable(scheduled_exception_address),
-         Immediate(Factory::the_hole_value()));
+      Immediate(Factory::the_hole_value()));
   j(not_equal, &promote_scheduled_exception, not_taken);
   LeaveApiExitFrame();
   ret(stack_space * kPointerSize);
@@ -1545,12 +1618,22 @@
       mov(dst, Operand(dst, Context::SlotOffset(Context::CLOSURE_INDEX)));
       mov(dst, FieldOperand(dst, JSFunction::kContextOffset));
     }
-    // The context may be an intermediate context, not a function context.
-    mov(dst, Operand(dst, Context::SlotOffset(Context::FCONTEXT_INDEX)));
-  } else {  // Slot is in the current function context.
-    // The context may be an intermediate context, not a function context.
-    mov(dst, Operand(esi, Context::SlotOffset(Context::FCONTEXT_INDEX)));
+  } else {
+    // Slot is in the current function context.  Move it into the
+    // destination register in case we store into it (the write barrier
+    // cannot be allowed to destroy the context in esi).
+    mov(dst, esi);
   }
+
+  // We should not have found a 'with' context by walking the context chain
+  // (i.e., the static scope chain and runtime context chain do not agree).
+  // A variable occurring in such a scope should have slot type LOOKUP and
+  // not CONTEXT.
+  if (FLAG_debug_code) {
+    cmp(dst, Operand(dst, Context::SlotOffset(Context::FCONTEXT_INDEX)));
+    Check(equal, "Yo dawg, I heard you liked function contexts "
+                 "so I put function contexts in all your contexts");
+  }
 }
 
 
@@ -1593,6 +1676,20 @@
 }
 
 
+void MacroAssembler::Ret(int bytes_dropped, Register scratch) {
+  if (is_uint16(bytes_dropped)) {
+    ret(bytes_dropped);
+  } else {
+    pop(scratch);
+    add(Operand(esp), Immediate(bytes_dropped));
+    push(scratch);
+    ret(0);
+  }
+}
+
+
+
+
 void MacroAssembler::Drop(int stack_elements) {
   if (stack_elements > 0) {
     add(Operand(esp), Immediate(stack_elements * kPointerSize));
@@ -1735,7 +1832,7 @@
   }
 #endif
   // Disable stub call restrictions to always allow calls to abort.
-  set_allow_stub_calls(true);
+  AllowStubCallsScope allow_scope(this, true);
 
   push(eax);
   push(Immediate(p0));