Apologize, I pressed the wrong key and the message was sent before I
completed it. Bellow is the complete implementation of the custom lowering
function:
static SDValue LowerExtLoad(SDValue Op, SelectionDAG &DAG) {
LoadSDNode *LD = dyn_cast<LoadSDNode>(Op.getNode());
ISD::LoadExtType ExtType = LD->getExtensionType();
if (LD->getExtensionType() == ISD::ZEXTLOAD) {
DEBUG(errs() << "ZEXTLOAD\n");
SDValue Chain = LD->getChain();
SDValue Ptr = LD->getBasePtr();
DebugLoc dl = Op.getNode()->getDebugLoc();
SDValue LdResult = DAG.getExtLoad(ISD::EXTLOAD, dl, MVT::i32,
Chain, Ptr, LD->getPointerInfo(),
MVT::i32,
LD->isVolatile(),
LD->isNonTemporal(),
LD->getAlignment());
Chain = LdResult.getValue(1);
SDValue Mask = DAG.getConstant(0xffff, MVT::i32);
DAG.ReplaceAllUsesOfValueWith(SDValue(LD, 0), LdResult);
DAG.ReplaceAllUsesOfValueWith(SDValue(LD, 1), Chain);
DAG.RemoveDeadNode(LD);
return DAG.getNode(ISD::AND, dl, MVT::i32, LdResult, Mask);
}
else
return Op;
}
However, when I get the following error during the compilation of the test
file.
llc:
/files3/scratch/gho705/llvm/llvm-3.2.src/lib/CodeGen/SelectionDAG/SelectionDAG.cpp:694:
bool llvm::SelectionDAG::RemoveNodeFromCSEMaps(llvm::SDNode*): Assertion
`N->getOpcode() != ISD::DELETED_NODE && "DELETED_NODE in
CSEMap!"' failed.
I am wondering what was wrong with the way I removed the current illegal
extending load?
Thank you,
Giang
On Mon, Mar 4, 2013 at 3:14 PM, Giang Hoang <ghoang84 at gmail.com> wrote:
> Hi,
>
> For my research, I need to reshape the current ARM backend to support
> armv2a. Zero-extend half word load (ldrh) is not supported by armv2a, so I
> need to make the code generation to not generate ldrh instructions. I want
> to replace all those instances with a 32-bit load (ldr) and then and the
> result with 0xffff to mask out the upper bits.
>
> These are the modifications that I have made to accomplish that:
>
> 1. Register the ZEXTLOAD for custom lowering:
>
> setLoadExtAction(ISD::ZEXTLOAD, MVT::i16, Custom);
>
> 2. Implement a custom lowering function:
>
> static SDValue LowerExtLoad(SDValue Op, SelectionDAG &DAG) {
> LoadSDNode *LD = dyn_cast<LoadSDNode>(Op.getNode());
> ISD::LoadExtType ExtType = LD->getExtensionType();
>
> if (LD->getExtensionType() == ISD::ZEXTLOAD) {
> DEBUG(errs() << "ZEXTLOAD\n");
> SDValue Chain = LD->getChain();
> SDValue Ptr = LD->getBasePtr();
> DebugLoc dl = Op.getNode()->getDebugLoc();
> SDValue LdResult = DAG.getExtLoad(ISD::EXTLOAD, dl, MVT::i32,
> Chain, Ptr, LD->getPointerInfo(),
> MVT::i32,
> LD->isVolatile(),
> LD->isNonTemporal(),
> LD->getAlignment());
> Chain = LdResult.getValue(1);
> SDValue Mask = DAG.getConstant(0x1, MVT::i32);
>
>
>
> DAG.ReplaceAllUsesOfValueWith(SDValue(LD, 0), LdResult);
> DAG.ReplaceAllUsesOfValueWith(SDValue(LD, 1), Chain);
> DAG.RemoveDeadNode(LD);
> //return DAG.getNode(ISD::AND, dl, MVT::i32, Op, Mask);
>
>
>
> }
>
> }
>
>
>
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