path: root/lib/CodeGen/CGCleanup.cpp

//===--- CGCleanup.cpp - Bookkeeping and code emission for cleanups -------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains code dealing with the IR generation for cleanups
// and related information.
//
// A "cleanup" is a piece of code which needs to be executed whenever
// control transfers out of a particular scope.  This can be
// conditionalized to occur only on exceptional control flow, only on
// normal control flow, or both.
//
//===----------------------------------------------------------------------===//

#include "CodeGenFunction.h"
#include "CGCleanup.h"

using namespace clang;
using namespace CodeGen;

bool DominatingValue<RValue>::saved_type::needsSaving(RValue rv) {
  if (rv.isScalar())
    return DominatingLLVMValue::needsSaving(rv.getScalarVal());
  if (rv.isAggregate())
    return DominatingLLVMValue::needsSaving(rv.getAggregateAddr());
  return true;
}

DominatingValue<RValue>::saved_type
DominatingValue<RValue>::saved_type::save(CodeGenFunction &CGF, RValue rv) {
  if (rv.isScalar()) {
    llvm::Value *V = rv.getScalarVal();

    // These automatically dominate and don't need to be saved.
    if (!DominatingLLVMValue::needsSaving(V))
      return saved_type(V, ScalarLiteral);

    // Everything else needs an alloca.
    llvm::Value *addr = CGF.CreateTempAlloca(V->getType(), "saved-rvalue");
    CGF.Builder.CreateStore(V, addr);
    return saved_type(addr, ScalarAddress);
  }

  if (rv.isComplex()) {
    CodeGenFunction::ComplexPairTy V = rv.getComplexVal();
    llvm::Type *ComplexTy =
      llvm::StructType::get(V.first->getType(), V.second->getType(),
                            (void*) 0);
    llvm::Value *addr = CGF.CreateTempAlloca(ComplexTy, "saved-complex");
    CGF.Builder.CreateStore(V.first, CGF.Builder.CreateStructGEP(addr, 0));
    CGF.Builder.CreateStore(V.second, CGF.Builder.CreateStructGEP(addr, 1));
    return saved_type(addr, ComplexAddress);
  }

  assert(rv.isAggregate());
  llvm::Value *V = rv.getAggregateAddr(); // TODO: volatile?
  if (!DominatingLLVMValue::needsSaving(V))
    return saved_type(V, AggregateLiteral);

  llvm::Value *addr = CGF.CreateTempAlloca(V->getType(), "saved-rvalue");
  CGF.Builder.CreateStore(V, addr);
  return saved_type(addr, AggregateAddress);  
}

/// Given a saved r-value produced by SaveRValue, perform the code
/// necessary to restore it to usability at the current insertion
/// point.
RValue DominatingValue<RValue>::saved_type::restore(CodeGenFunction &CGF) {
  switch (K) {
  case ScalarLiteral:
    return RValue::get(Value);
  case ScalarAddress:
    return RValue::get(CGF.Builder.CreateLoad(Value));
  case AggregateLiteral:
    return RValue::getAggregate(Value);
  case AggregateAddress:
    return RValue::getAggregate(CGF.Builder.CreateLoad(Value));
  case ComplexAddress: {
    llvm::Value *real =
      CGF.Builder.CreateLoad(CGF.Builder.CreateStructGEP(Value, 0));
    llvm::Value *imag =
      CGF.Builder.CreateLoad(CGF.Builder.CreateStructGEP(Value, 1));
    return RValue::getComplex(real, imag);
  }
  }

  llvm_unreachable("bad saved r-value kind");
}

/// Push an entry of the given size onto this protected-scope stack.
char *EHScopeStack::allocate(size_t Size) {
  if (!StartOfBuffer) {
    unsigned Capacity = 1024;
    while (Capacity < Size) Capacity