[interpreter] Remove OperandScale from front stages of pipeline.

src/interpreter/bytecode-array-writer.cc

 // Copyright 2015 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.
 
 #include "src/interpreter/bytecode-array-writer.h"
 
 #include "src/api.h"
 #include "src/interpreter/bytecode-label.h"
 #include "src/interpreter/constant-array-builder.h"
 #include "src/log.h"
@@ skipping 87 matching lines @@
     const BytecodeNode* const node) {
   int bytecode_offset = static_cast<int>(bytecodes()->size());
   const BytecodeSourceInfo& source_info = node->source_info();
   if (source_info.is_valid()) {
     source_position_table_builder()->AddPosition(bytecode_offset,
                                                  source_info.source_position(),
                                                  source_info.is_statement());
   }
 }
 
+namespace {
+
+OperandSize GetOperandSize(OperandTypeInfo operand_type_info,
+                           uint32_t operand_value) {
+  switch (operand_type_info) {
+    case OperandTypeInfo::kScalableSignedByte: {
+      int32_t signed_operand = static_cast<int32_t>(operand_value);
+      return Bytecodes::SizeForSignedOperand(signed_operand);
+    }
+    case OperandTypeInfo::kScalableUnsignedByte: {
+      return Bytecodes::SizeForUnsignedOperand(operand_value);
+    }
+    case OperandTypeInfo::kFixedUnsignedByte: {
+      return OperandSize::kByte;
+    }
+    case OperandTypeInfo::kFixedUnsignedShort: {
+      return OperandSize::kByte;

[rmcilroy, 2016/06/09 15:16:35]

kShort

[oth, 2016/06/09 19:59:07]

For the daft logic here, it's effectively 1 so Byte is the right enumeration.
This path needs to change.

+    }
+    case OperandTypeInfo::kNone:
+      break;
+  }
+  UNREACHABLE();
+  return OperandSize::kNone;
+}
+
+OperandScale GetOperandScale(const BytecodeNode* const node) {
+  const OperandTypeInfo* operand_type_infos =
+      Bytecodes::GetOperandTypeInfos(node->bytecode());

[rmcilroy, 2016/06/09 15:16:35]

Rather than doing this dance between Size and Scale, how about just checking
scalable operands, and having a OperandScaleFor[Un]SignedOperand and get the
maximum value for all scalable operands?

[oth, 2016/06/09 19:59:07]

Done.

+  switch (node->operand_count()) {
+    case 4:
+      return Bytecodes::OperandSizesToScale(
+          GetOperandSize(operand_type_infos[0], node->operand(0)),
+          GetOperandSize(operand_type_infos[1], node->operand(1)),
+          GetOperandSize(operand_type_infos[2], node->operand(2)),
+          GetOperandSize(operand_type_infos[3], node->operand(3)));
+      break;
+    case 3:
+      return Bytecodes::OperandSizesToScale(
+          GetOperandSize(operand_type_infos[0], node->operand(0)),
+          GetOperandSize(operand_type_infos[1], node->operand(1)),
+          GetOperandSize(operand_type_infos[2], node->operand(2)));
+      break;
+    case 2:
+      return Bytecodes::OperandSizesToScale(
+          GetOperandSize(operand_type_infos[0], node->operand(0)),
+          GetOperandSize(operand_type_infos[1], node->operand(1)));
+      break;
+    case 1:
+      return Bytecodes::OperandSizesToScale(
+          GetOperandSize(operand_type_infos[0], node->operand(0)));
+      break;
+    case 0:
+      return OperandScale::kSingle;
+  }
+  UNREACHABLE();
+  return OperandScale::kSingle;
+}
+
+}  // namespace
+
 void BytecodeArrayWriter::EmitBytecode(const BytecodeNode* const node) {
   DCHECK_NE(node->bytecode(), Bytecode::kIllegal);
 
-  OperandScale operand_scale = node->operand_scale();
+  OperandScale operand_scale = GetOperandScale(node);
   if (operand_scale != OperandScale::kSingle) {
     Bytecode prefix = Bytecodes::OperandScaleToPrefixBytecode(operand_scale);
     bytecodes()->push_back(Bytecodes::ToByte(prefix));
   }
 
   Bytecode bytecode = node->bytecode();
   bytecodes()->push_back(Bytecodes::ToByte(bytecode));
 
   int register_operand_bitmap = Bytecodes::GetRegisterOperandBitmap(bytecode);
   const uint32_t* const operands = node->operands();
@@ skipping 31 matching lines @@
         count = static_cast<int>(operands[i + 1]);
       } else {
         count = Bytecodes::GetNumberOfRegistersRepresentedBy(operand_type);
       }
       Register reg = Register::FromOperand(static_cast<int32_t>(operands[i]));
       max_register_count_ = std::max(max_register_count_, reg.index() + count);
     }
   }
 }
 
-// TODO(rmcilroy): This is the same as SignedOperand in BytecodeArrayBuilder.
-// Once we move the scalable operand processing here remove the SignedOperand
-// in BytecodeArrayBuilder.
-static uint32_t SignedOperand(int value, OperandSize size) {
-  switch (size) {
-    case OperandSize::kByte:
-      return static_cast<uint8_t>(value & 0xff);
-    case OperandSize::kShort:
-      return static_cast<uint16_t>(value & 0xffff);
-    case OperandSize::kQuad:
-      return static_cast<uint32_t>(value);
-    case OperandSize::kNone:
-      UNREACHABLE();
-  }
-  return 0;
-}
-
 // static
 Bytecode GetJumpWithConstantOperand(Bytecode jump_bytecode) {
   switch (jump_bytecode) {
     case Bytecode::kJump:
       return Bytecode::kJumpConstant;
     case Bytecode::kJumpIfTrue:
       return Bytecode::kJumpIfTrueConstant;
     case Bytecode::kJumpIfFalse:
       return Bytecode::kJumpIfFalseConstant;
     case Bytecode::kJumpIfToBooleanTrue:
@@ skipping 10 matching lines @@
       UNREACHABLE();
       return Bytecode::kIllegal;
   }
 }
 
 void BytecodeArrayWriter::PatchJumpWith8BitOperand(size_t jump_location,
                                                    int delta) {
   Bytecode jump_bytecode = Bytecodes::FromByte(bytecodes()->at(jump_location));
   DCHECK(Bytecodes::IsJumpImmediate(jump_bytecode));
   size_t operand_location = jump_location + 1;
-  DCHECK_EQ(bytecodes()->at(operand_location), 0);
+  DCHECK_EQ(bytecodes()->at(operand_location), k8BitJumpPlaceholder);
   if (Bytecodes::SizeForSignedOperand(delta) == OperandSize::kByte) {
     // The jump fits within the range of an Imm operand, so cancel
     // the reservation and jump directly.
     constant_array_builder()->DiscardReservedEntry(OperandSize::kByte);
     bytecodes()->at(operand_location) = static_cast<uint8_t>(delta);
   } else {
     // The jump does not fit within the range of an Imm operand, so
     // commit reservation putting the offset into the constant pool,
     // and update the jump instruction and operand.
     size_t entry = constant_array_builder()->CommitReservedEntry(
         OperandSize::kByte, handle(Smi::FromInt(delta), isolate()));
-    DCHECK(Bytecodes::SizeForUnsignedOperand(entry) == OperandSize::kByte);
+    DCHECK_LE(entry, kMaxUInt32);
+    DCHECK_EQ(Bytecodes::SizeForUnsignedOperand(static_cast<uint32_t>(entry)),
+              OperandSize::kByte);
     jump_bytecode = GetJumpWithConstantOperand(jump_bytecode);
     bytecodes()->at(jump_location) = Bytecodes::ToByte(jump_bytecode);
     bytecodes()->at(operand_location) = static_cast<uint8_t>(entry);
   }
 }
 
 void BytecodeArrayWriter::PatchJumpWith16BitOperand(size_t jump_location,
                                                     int delta) {
   Bytecode jump_bytecode = Bytecodes::FromByte(bytecodes()->at(jump_location));
   DCHECK(Bytecodes::IsJumpImmediate(jump_bytecode));
   size_t operand_location = jump_location + 1;
   uint8_t operand_bytes[2];
   if (Bytecodes::SizeForSignedOperand(delta) <= OperandSize::kShort) {
     constant_array_builder()->DiscardReservedEntry(OperandSize::kShort);
     WriteUnalignedUInt16(operand_bytes, static_cast<uint16_t>(delta));
   } else {
     jump_bytecode = GetJumpWithConstantOperand(jump_bytecode);
     bytecodes()->at(jump_location) = Bytecodes::ToByte(jump_bytecode);
     size_t entry = constant_array_builder()->CommitReservedEntry(
         OperandSize::kShort, handle(Smi::FromInt(delta), isolate()));
     WriteUnalignedUInt16(operand_bytes, static_cast<uint16_t>(entry));
   }
-  DCHECK(bytecodes()->at(operand_location) == 0 &&
-         bytecodes()->at(operand_location + 1) == 0);
+  DCHECK(bytecodes()->at(operand_location) == k8BitJumpPlaceholder &&
+         bytecodes()->at(operand_location + 1) == k8BitJumpPlaceholder);
   bytecodes()->at(operand_location++) = operand_bytes[0];
   bytecodes()->at(operand_location) = operand_bytes[1];
 }
 
 void BytecodeArrayWriter::PatchJumpWith32BitOperand(size_t jump_location,
                                                     int delta) {
   DCHECK(Bytecodes::IsJumpImmediate(
       Bytecodes::FromByte(bytecodes()->at(jump_location))));
   constant_array_builder()->DiscardReservedEntry(OperandSize::kQuad);
   uint8_t operand_bytes[4];
   WriteUnalignedUInt32(operand_bytes, static_cast<uint32_t>(delta));
   size_t operand_location = jump_location + 1;
-  DCHECK(bytecodes()->at(operand_location) == 0 &&
-         bytecodes()->at(operand_location + 1) == 0 &&
-         bytecodes()->at(operand_location + 2) == 0 &&
-         bytecodes()->at(operand_location + 3) == 0);
+  DCHECK(bytecodes()->at(operand_location) == k8BitJumpPlaceholder &&
+         bytecodes()->at(operand_location + 1) == k8BitJumpPlaceholder &&
+         bytecodes()->at(operand_location + 2) == k8BitJumpPlaceholder &&
+         bytecodes()->at(operand_location + 3) == k8BitJumpPlaceholder);
   bytecodes()->at(operand_location++) = operand_bytes[0];
   bytecodes()->at(operand_location++) = operand_bytes[1];
   bytecodes()->at(operand_location++) = operand_bytes[2];
   bytecodes()->at(operand_location) = operand_bytes[3];
 }
 
 void BytecodeArrayWriter::PatchJump(size_t jump_target, size_t jump_location) {
   Bytecode jump_bytecode = Bytecodes::FromByte(bytecodes()->at(jump_location));
   int delta = static_cast<int>(jump_target - jump_location);
   int prefix_offset = 0;
@@ skipping 36 matching lines @@
     CHECK_LE(current_offset, static_cast<size_t>(kMaxInt));
     // Label has been bound already so this is a backwards jump.
     size_t abs_delta = current_offset - label->offset();
     int delta = -static_cast<int>(abs_delta);
     OperandSize operand_size = Bytecodes::SizeForSignedOperand(delta);
     if (operand_size > OperandSize::kByte) {
       // Adjust for scaling byte prefix for wide jump offset.
       DCHECK_LE(delta, 0);
       delta -= 1;
     }
-    node->set_bytecode(node->bytecode(), SignedOperand(delta, operand_size),
-                       Bytecodes::OperandSizesToScale(operand_size));
+    node->set_bytecode(node->bytecode(), delta);
   } else {
     // The label has not yet been bound so this is a forward reference
     // that will be patched when the label is bound. We create a
     // reservation in the constant pool so the jump can be patched
     // when the label is bound. The reservation means the maximum size
     // of the operand for the constant is known and the jump can
     // be emitted into the bytecode stream with space for the operand.
     unbound_jumps_++;
     label->set_referrer(current_offset);
     OperandSize reserved_operand_size =
         constant_array_builder()->CreateReservedEntry();
-    OperandScale operand_scale =
-        Bytecodes::OperandSizesToScale(reserved_operand_size);
-    node->set_bytecode(node->bytecode(), 0, operand_scale);
+    switch (reserved_operand_size) {
+      case OperandSize::kNone:
+        UNREACHABLE();
+        break;
+      case OperandSize::kByte:
+        node->set_bytecode(node->bytecode(), k8BitJumpPlaceholder);
+        break;
+      case OperandSize::kShort:
+        node->set_bytecode(node->bytecode(), k16BitJumpPlaceholder);
+        break;
+      case OperandSize::kQuad:
+        node->set_bytecode(node->bytecode(), k32BitJumpPlaceholder);
+        break;
+    }
   }
   EmitBytecode(node);
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8