// Copyright (c) 2015-2016 The Khronos Group Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// Source code for logical layout validation as described in section 2.4

#include "source/val/validate.h"

#include <cassert>

#include "source/diagnostic.h"
#include "source/opcode.h"
#include "source/operand.h"
#include "source/val/function.h"
#include "source/val/instruction.h"
#include "source/val/validation_state.h"

namespace spvtools {
namespace val {
namespace {

// Module scoped instructions are processed by determining if the opcode
// is part of the current layout section. If it is not then the next sections is
// checked.
spv_result_t ModuleScopedInstructions(ValidationState_t& _,
                                      const Instruction* inst, SpvOp opcode) {
  switch (opcode) {
    case SpvOpExtInst:
      if (spvExtInstIsNonSemantic(inst->ext_inst_type())) {
        // non-semantic extinst opcodes are allowed beginning in the types
        // section, but since they must name a return type they cannot be the
        // first instruction in the types section. Therefore check that we are
        // already in it.
        if (_.current_layout_section() < kLayoutTypes) {
          return _.diag(SPV_ERROR_INVALID_LAYOUT, inst)
                 << "Non-semantic OpExtInst must not appear before types "
                 << "section";
        }
      } else {
        // otherwise they must be used in a block
        if (_.current_layout_section() < kLayoutFunctionDefinitions) {
          return _.diag(SPV_ERROR_INVALID_LAYOUT, inst)
                 << spvOpcodeString(opcode) << " must appear in a block";
        }
      }
      break;
    default:
      break;
  }

  while (_.IsOpcodeInCurrentLayoutSection(opcode) == false) {
    _.ProgressToNextLayoutSectionOrder();

    switch (_.current_layout_section()) {
      case kLayoutMemoryModel:
        if (opcode != SpvOpMemoryModel) {
          return _.diag(SPV_ERROR_INVALID_LAYOUT, inst)
                 << spvOpcodeString(opcode)
                 << " cannot appear before the memory model instruction";
        }
        break;
      case kLayoutFunctionDeclarations:
        // All module sections have been processed. Recursively call
        // ModuleLayoutPass to process the next section of the module
        return ModuleLayoutPass(_, inst);
      default:
        break;
    }
  }
  return SPV_SUCCESS;
}

// Function declaration validation is performed by making sure that the
// FunctionParameter and FunctionEnd instructions only appear inside of
// functions. It also ensures that the Function instruction does not appear
// inside of another function. This stage ends when the first label is
// encountered inside of a function.
spv_result_t FunctionScopedInstructions(ValidationState_t& _,
                                        const Instruction* inst, SpvOp opcode) {
  if (_.IsOpcodeInCurrentLayoutSection(opcode)) {
    switch (opcode) {
      case SpvOpFunction: {
        if (_.in_function_body()) {
          return _.diag(SPV_ERROR_INVALID_LAYOUT, inst)
                 << "Cannot declare a function in a function body";
        }
        auto control_mask = inst->GetOperandAs<SpvFunctionControlMask>(2);
        if (auto error =
                _.RegisterFunction(inst->id(), inst->type_id(), control_mask,
                                   inst->GetOperandAs<uint32_t>(3)))
          return error;
        if (_.current_layout_section() == kLayoutFunctionDefinitions) {
          if (auto error = _.current_function().RegisterSetFunctionDeclType(
                  FunctionDecl::kFunctionDeclDefinition))
            return error;
        }
      } break;

      case SpvOpFunctionParameter:
        if (_.in_function_body() == false) {
          return _.diag(SPV_ERROR_INVALID_LAYOUT, inst)
                 << "Function parameter instructions must be in a "
                    "function body";
        }
        if (_.current_function().block_count() != 0) {
          return _.diag(SPV_ERROR_INVALID_LAYOUT, inst)
                 << "Function parameters must only appear immediately after "
                    "the function definition";
        }
        if (auto error = _.current_function().RegisterFunctionParameter(
                inst->id(), inst->type_id()))
          return error;
        break;

      case SpvOpFunctionEnd:
        if (_.in_function_body() == false) {
          return _.diag(SPV_ERROR_INVALID_LAYOUT, inst)
                 << "Function end instructions must be in a function body";
        }
        if (_.in_block()) {
          return _.diag(SPV_ERROR_INVALID_LAYOUT, inst)
                 << "Function end cannot be called in blocks";
        }
        if (_.current_function().block_count() == 0 &&
            _.current_layout_section() == kLayoutFunctionDefinitions) {
          return _.diag(SPV_ERROR_INVALID_LAYOUT, inst)
                 << "Function declarations must appear before "
                    "function definitions.";
        }
        if (_.current_layout_section() == kLayoutFunctionDeclarations) {
          if (auto error = _.current_function().RegisterSetFunctionDeclType(
                  FunctionDecl::kFunctionDeclDeclaration))
            return error;
        }
        if (auto error = _.RegisterFunctionEnd()) return error;
        break;

      case SpvOpLine:
      case SpvOpNoLine:
        break;
      case SpvOpLabel:
        // If the label is encountered then the current function is a
        // definition so set the function to a declaration and update the
        // module section
        if (_.in_function_body() == false) {
          return _.diag(SPV_ERROR_INVALID_LAYOUT, inst)
                 << "Label instructions must be in a function body";
        }
        if (_.in_block()) {
          return _.diag(SPV_ERROR_INVALID_LAYOUT, inst)
                 << "A block must end with a branch instruction.";
        }
        if (_.current_layout_section() == kLayoutFunctionDeclarations) {
          _.ProgressToNextLayoutSectionOrder();
          if (auto error = _.current_function().RegisterSetFunctionDeclType(
                  FunctionDecl::kFunctionDeclDefinition))
            return error;
        }
        break;

      case SpvOpExtInst:
        if (spvExtInstIsNonSemantic(inst->ext_inst_type())) {
          // non-semantic extinst opcodes are allowed beginning in the types
          // section, but must either be placed outside a function declaration,
          // or inside a block.
          if (_.current_layout_section() < kLayoutTypes) {
            return _.diag(SPV_ERROR_INVALID_LAYOUT, inst)
                   << "Non-semantic OpExtInst must not appear before types "
                   << "section";
          } else if (_.in_function_body() && _.in_block() == false) {
            return _.diag(SPV_ERROR_INVALID_LAYOUT, inst)
                   << "Non-semantic OpExtInst within function definition must "
                      "appear in a block";
          }
        } else {
          // otherwise they must be used in a block
          if (_.in_block() == false) {
            return _.diag(SPV_ERROR_INVALID_LAYOUT, inst)
                   << spvOpcodeString(opcode) << " must appear in a block";
          }
        }
        break;

      default:
        if (_.current_layout_section() == kLayoutFunctionDeclarations &&
            _.in_function_body()) {
          return _.diag(SPV_ERROR_INVALID_LAYOUT, inst)
                 << "A function must begin with a label";
        } else {
          if (_.in_block() == false) {
            return _.diag(SPV_ERROR_INVALID_LAYOUT, inst)
                   << spvOpcodeString(opcode) << " must appear in a block";
          }
        }
        break;
    }
  } else {
    return _.diag(SPV_ERROR_INVALID_LAYOUT, inst)
           << spvOpcodeString(opcode)
           << " cannot appear in a function declaration";
  }
  return SPV_SUCCESS;
}

}  // namespace

// TODO(umar): Check linkage capabilities for function declarations
// TODO(umar): Better error messages
// NOTE: This function does not handle CFG related validation
// Performs logical layout validation. See Section 2.4
spv_result_t ModuleLayoutPass(ValidationState_t& _, const Instruction* inst) {
  const SpvOp opcode = inst->opcode();

  switch (_.current_layout_section()) {
    case kLayoutCapabilities:
    case kLayoutExtensions:
    case kLayoutExtInstImport:
    case kLayoutMemoryModel:
    case kLayoutEntryPoint:
    case kLayoutExecutionMode:
    case kLayoutDebug1:
    case kLayoutDebug2:
    case kLayoutDebug3:
    case kLayoutAnnotations:
    case kLayoutTypes:
      if (auto error = ModuleScopedInstructions(_, inst, opcode)) return error;
      break;
    case kLayoutFunctionDeclarations:
    case kLayoutFunctionDefinitions:
      if (auto error = FunctionScopedInstructions(_, inst, opcode)) {
        return error;
      }
      break;
  }
  return SPV_SUCCESS;
}

}  // namespace val
}  // namespace spvtools