当前位置: 首页>>代码示例>>C++>>正文


C++ TargetLowering::getTypeAction方法代码示例

本文整理汇总了C++中TargetLowering::getTypeAction方法的典型用法代码示例。如果您正苦于以下问题:C++ TargetLowering::getTypeAction方法的具体用法?C++ TargetLowering::getTypeAction怎么用?C++ TargetLowering::getTypeAction使用的例子?那么恭喜您, 这里精选的方法代码示例或许可以为您提供帮助。您也可以进一步了解该方法所在TargetLowering的用法示例。


在下文中一共展示了TargetLowering::getTypeAction方法的1个代码示例,这些例子默认根据受欢迎程度排序。您可以为喜欢或者感觉有用的代码点赞,您的评价将有助于系统推荐出更棒的C++代码示例。

示例1: OptimizeNoopCopyExpression

/// OptimizeNoopCopyExpression - If the specified cast instruction is a noop
/// copy (e.g. it's casting from one pointer type to another, i32->i8 on PPC),
/// sink it into user blocks to reduce the number of virtual
/// registers that must be created and coalesced.
///
/// Return true if any changes are made.
///
static bool OptimizeNoopCopyExpression(CastInst *CI, const TargetLowering &TLI) {
    // If this is a noop copy,
    EVT SrcVT = TLI.getValueType(CI->getOperand(0)->getType());
    EVT DstVT = TLI.getValueType(CI->getType());

    // This is an fp<->int conversion?
    if (SrcVT.isInteger() != DstVT.isInteger())
        return false;

    // If this is an extension, it will be a zero or sign extension, which
    // isn't a noop.
    if (SrcVT.bitsLT(DstVT)) return false;

    // If these values will be promoted, find out what they will be promoted
    // to.  This helps us consider truncates on PPC as noop copies when they
    // are.
    if (TLI.getTypeAction(CI->getContext(), SrcVT) ==
            TargetLowering::TypePromoteInteger)
        SrcVT = TLI.getTypeToTransformTo(CI->getContext(), SrcVT);
    if (TLI.getTypeAction(CI->getContext(), DstVT) ==
            TargetLowering::TypePromoteInteger)
        DstVT = TLI.getTypeToTransformTo(CI->getContext(), DstVT);

    // If, after promotion, these are the same types, this is a noop copy.
    if (SrcVT != DstVT)
        return false;

    BasicBlock *DefBB = CI->getParent();

    /// InsertedCasts - Only insert a cast in each block once.
    DenseMap<BasicBlock*, CastInst*> InsertedCasts;

    bool MadeChange = false;
    for (Value::use_iterator UI = CI->use_begin(), E = CI->use_end();
            UI != E; ) {
        Use &TheUse = UI.getUse();
        Instruction *User = cast<Instruction>(*UI);

        // Figure out which BB this cast is used in.  For PHI's this is the
        // appropriate predecessor block.
        BasicBlock *UserBB = User->getParent();
        if (PHINode *PN = dyn_cast<PHINode>(User)) {
            UserBB = PN->getIncomingBlock(UI);
        }

        // Preincrement use iterator so we don't invalidate it.
        ++UI;

        // If this user is in the same block as the cast, don't change the cast.
        if (UserBB == DefBB) continue;

        // If we have already inserted a cast into this block, use it.
        CastInst *&InsertedCast = InsertedCasts[UserBB];

        if (!InsertedCast) {
            BasicBlock::iterator InsertPt = UserBB->getFirstInsertionPt();
            InsertedCast =
                CastInst::Create(CI->getOpcode(), CI->getOperand(0), CI->getType(), "",
                                 InsertPt);
            MadeChange = true;
        }

        // Replace a use of the cast with a use of the new cast.
        TheUse = InsertedCast;
        ++NumCastUses;
    }

    // If we removed all uses, nuke the cast.
    if (CI->use_empty()) {
        CI->eraseFromParent();
        MadeChange = true;
    }

    return MadeChange;
}
开发者ID:PhongNgo,项目名称:llvm,代码行数:82,代码来源:CodeGenPrepare.cpp


注:本文中的TargetLowering::getTypeAction方法示例由纯净天空整理自Github/MSDocs等开源代码及文档管理平台,相关代码片段筛选自各路编程大神贡献的开源项目,源码版权归原作者所有,传播和使用请参考对应项目的License;未经允许,请勿转载。