[Atomics] code stubs for atomic operations

src/arm/code-stubs-arm.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #if V8_TARGET_ARCH_ARM
 
 #include "src/base/bits.h"
 #include "src/bootstrapper.h"
 #include "src/code-stubs.h"
 #include "src/codegen.h"
@@ skipping 5426 matching lines @@
       ExternalReference::invoke_accessor_getter_callback(isolate());
 
   // +3 is to skip prolog, return address and name handle.
   MemOperand return_value_operand(
       fp, (PropertyCallbackArguments::kReturnValueOffset + 3) * kPointerSize);
   CallApiFunctionAndReturn(masm, api_function_address, thunk_ref,
                            kStackUnwindSpace, NULL, return_value_operand, NULL);
 }
 
 
+static void GetTypedArrayBackingStore(MacroAssembler* masm,

[Jarin, 2016/01/28 08:11:12]

Nit: Anonymous namespace for all the static methods, please.

[binji, 2016/01/28 16:20:00]

Happy to do it, but it doesn't seem to be consistent with the rest of the file.
Should I change the others too?

[Jarin, 2016/02/01 07:42:43]

I see your point, but I still think new code should not use statics. However,
this is just a nit, so I am happy with whatever decision you make.

+                                      Register backing_store,
+                                      Register object,
+                                      Register scratch,
+                                      LowDwVfpRegister double_scratch) {
+  Label offset_is_not_smi, done;
+  __ ldr(scratch, FieldMemOperand(object, JSTypedArray::kBufferOffset));
+  __ ldr(backing_store,
+         FieldMemOperand(scratch, JSArrayBuffer::kBackingStoreOffset));
+  __ ldr(scratch,
+         FieldMemOperand(object, JSArrayBufferView::kByteOffsetOffset));
+  __ UntagAndJumpIfNotSmi(scratch, scratch, &offset_is_not_smi);
+  // offset is smi

[Jarin, 2016/01/28 08:11:12]

Nit: If a comment is a sentence, it should start with a capital letter and end
with a dot.

[binji, 2016/01/28 16:20:00]

Done.

+  __ add(backing_store, backing_store, scratch);
+  __ jmp(&done);
+
+  // offset is a heap number
+  __ bind(&offset_is_not_smi);
+  __ vldr(double_scratch, scratch, HeapNumber::kValueOffset - kHeapObjectTag);
+  __ vcvt_u32_f64(double_scratch.low(), double_scratch);
+  __ vmov(scratch, double_scratch.low());
+  __ add(backing_store, backing_store, scratch);
+  __ bind(&done);
+}
+
+
+static void TaggedToInteger32(MacroAssembler* masm,
+                              Register value,
+                              LowDwVfpRegister double_scratch) {
+  Label not_smi, done;
+  __ UntagAndJumpIfNotSmi(value, value, &not_smi);
+  __ jmp(&done);
+
+  __ bind(&not_smi);
+  __ vldr(double_scratch, value, HeapNumber::kValueOffset - kHeapObjectTag);
+  __ vmov(value, double_scratch.low());
+  __ bind(&done);
+}
+
+
+static void TypedArrayJumpTable(MacroAssembler* masm,
+                                Register object,
+                                Register scratch,
+                                Register scratch2,
+                                Label* i8,
+                                Label* u8,
+                                Label* i16,
+                                Label* u16,
+                                Label* i32,
+                                Label* u32,
+                                Label* u8c) {
+  STATIC_ASSERT(FIXED_UINT8_ARRAY_TYPE == FIXED_INT8_ARRAY_TYPE + 1);
+  STATIC_ASSERT(FIXED_INT16_ARRAY_TYPE == FIXED_INT8_ARRAY_TYPE + 2);
+  STATIC_ASSERT(FIXED_UINT16_ARRAY_TYPE == FIXED_INT8_ARRAY_TYPE + 3);
+  STATIC_ASSERT(FIXED_INT32_ARRAY_TYPE == FIXED_INT8_ARRAY_TYPE + 4);
+  STATIC_ASSERT(FIXED_UINT32_ARRAY_TYPE == FIXED_INT8_ARRAY_TYPE + 5);
+  STATIC_ASSERT(FIXED_FLOAT32_ARRAY_TYPE == FIXED_INT8_ARRAY_TYPE + 6);
+  STATIC_ASSERT(FIXED_FLOAT64_ARRAY_TYPE == FIXED_INT8_ARRAY_TYPE + 7);
+  STATIC_ASSERT(FIXED_UINT8_CLAMPED_ARRAY_TYPE == FIXED_INT8_ARRAY_TYPE + 8);

[Jarin, 2016/01/28 08:11:12]

I like this. Thanks!

[binji, 2016/01/28 16:20:00]

Yeah, it's a bit paranoid, but doesn't really hurt. :)

[Jarin, 2016/02/01 07:42:43]

I actually like that it explicitly states what you rely on for documentation. It
is actually the best kind of documentation, checked documentation!

+
+  __ ldr(scratch, FieldMemOperand(object, JSObject::kElementsOffset));
+  __ ldr(scratch, FieldMemOperand(scratch, HeapObject::kMapOffset));
+  __ ldrb(scratch, FieldMemOperand(scratch, Map::kInstanceTypeOffset));
+  __ mov(scratch2, Operand(static_cast<uint8_t>(FIXED_INT8_ARRAY_TYPE)));
+  __ sub(scratch, scratch, scratch2, SetCC);
+  __ Assert(ge, kOffsetOutOfRange);
+
+  Label abort;
+
+  {
+    Assembler::BlockConstPoolScope scope(masm);
+    __ add(pc, pc, Operand(scratch, LSL, 2));
+    __ nop();
+    __ b(i8);      // Int8Array
+    __ b(u8);      // Uint8Array
+    __ b(i16);     // Int16Array
+    __ b(u16);     // Uint16Array
+    __ b(i32);     // Int32Array
+    __ b(u32);     // Uint32Array
+    __ b(&abort);  // Float32Array
+    __ b(&abort);  // Float64Array
+    __ b(u8);      // Uint8ClampedArray

[Jarin, 2016/01/28 08:11:12]

This should be u8c, no? (Also on all other platforms.)

[binji, 2016/01/28 16:20:00]

oops. In this case it is fine (because AtomicLoad is the same for u8 and u8c)
but it will break for all the others.

+  }
+
+  __ bind(&abort);
+  __ Abort(kNoReason);
+}
+
+
+static void ReturnInteger32(MacroAssembler* masm,
+                            DwVfpRegister dst,
+                            Register value,
+                            SwVfpRegister single_scratch,
+                            Label* use_heap_number) {
+  Label not_smi;
+  __ TrySmiTag(r0, value, &not_smi);
+  __ Ret();
+
+  __ bind(&not_smi);
+  __ vmov(single_scratch, value);
+  __ vcvt_f64_s32(dst, single_scratch);
+  __ jmp(use_heap_number);
+}
+
+
+static void ReturnUnsignedInteger32(MacroAssembler* masm,
+                                    DwVfpRegister dst,
+                                    Register value,
+                                    Register scratch,
+                                    SwVfpRegister single_scratch,
+                                    Label* use_heap_number) {
+  Label not_smi;
+  __ mov(scratch, Operand(0x40000000U));
+  __ cmp(value, scratch);
+  __ b(cs, &not_smi);
+  __ SmiTag(r0, value);
+  __ Ret();
+
+  __ bind(&not_smi);
+  __ vmov(single_scratch, value);
+  __ vcvt_f64_u32(dst, single_scratch);
+  __ jmp(use_heap_number);
+}
+
+
+static void ReturnAllocatedHeapNumber(MacroAssembler* masm,
+                                      DwVfpRegister value,
+                                      Register scratch,
+                                      Register scratch2,
+                                      Register scratch3) {
+  Label call_runtime;
+  __ LoadRoot(scratch3, Heap::kHeapNumberMapRootIndex);
+  __ AllocateHeapNumber(r0, scratch, scratch2, scratch3, &call_runtime);
+  __ vstr(value, FieldMemOperand(r0, HeapNumber::kValueOffset));
+  __ Ret();
+
+  __ bind(&call_runtime);
+  {
+    FrameScope scope(masm, StackFrame::INTERNAL);
+    __ CallRuntimeSaveDoubles(Runtime::kAllocateHeapNumber);
+    __ vstr(value, FieldMemOperand(r0, HeapNumber::kValueOffset));
+  }
+  __ Ret();
+}
+
+
+void AtomicsLoadStub::Generate(MacroAssembler* masm) {
+  Register object = r1;
+  Register backing_store = r2;
+  Register index = r0;
+  Label i8, u8, i16, u16, i32, u32;
+
+  GetTypedArrayBackingStore(masm, backing_store, object, r3, d0);
+  TaggedToInteger32(masm, index, d0);
+  TypedArrayJumpTable(masm, object, r3, r4, &i8, &u8, &i16, &u16, &i32, &u32,
+                      &u8);
+
+  __ bind(&i8);
+  __ ldrb(r0, MemOperand(backing_store, index));
+  __ dmb(ISH);
+  __ sxtb(r0, r0);
+  __ SmiTag(r0);
+  __ Ret();
+
+  __ bind(&u8);
+  __ ldrb(r0, MemOperand(backing_store, index));
+  __ dmb(ISH);
+  __ SmiTag(r0);
+  __ Ret();
+
+  __ bind(&i16);
+  __ ldrh(r0, MemOperand(backing_store, index, LSL, 1));
+  __ dmb(ISH);
+  __ sxth(r0, r0);
+  __ SmiTag(r0);
+  __ Ret();
+
+  __ bind(&u16);
+  __ ldrh(r0, MemOperand(backing_store, index, LSL, 1));
+  __ dmb(ISH);
+  __ SmiTag(r0);
+  __ Ret();
+
+  Label use_heap_number;
+
+  __ bind(&i32);
+  __ ldr(r0, MemOperand(backing_store, index, LSL, 2));
+  __ dmb(ISH);
+  ReturnInteger32(masm, d0, r0, s2, &use_heap_number);
+
+  __ bind(&u32);
+  __ ldr(r0, MemOperand(backing_store, index, LSL, 2));
+  __ dmb(ISH);
+  ReturnUnsignedInteger32(masm, d0, r0, r1, s2, &use_heap_number);
+
+  __ bind(&use_heap_number);
+  ReturnAllocatedHeapNumber(masm, d0, r1, r2, r3);
+}
+
+
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_ARM