TableGen: Add support of Intrinsics with multiple returns

[wenbos]

Summary

This patch deals with intrinsics with multiple outputs, for example load instrinsic with address updated. 
 
DAG selection for Instrinsics could be done either through source code or tablegen. Handling all intrinsics in source code would introduce a huge chunk of repetitive code if we have a large number of intrinsic that return multiple values (see NVPTX as an example).  While intrinsic class in tablegen supports multiple outputs, tablegen only supports Intrinsics with zero or one output on TreePattern. This appears to be a simple bug in tablegen that is fixed by this patch.

Intrinsics is defined as:

def int_xxx_load_addr_updated: Intrinsic<[llvm_i32_ty, llvm_ptr_ty], [llvm_ptr_ty, llvm_i32_ty], []>;

Instruction will be defined as:

def L32_X: Inst<(outs reg:$d1, reg:$d2), (ins reg:$s1, reg:$s2), "ld32_x $d1, $d2, $s2", [(set i32:$d1, i32:$d2, (int_xxx_load_addr_updated i32:$s1, i32:$s2))]>;

[MatzeB]

Unfortunately I am not a good reviewer for the DAGPattern part of TableGen. Adding some people who may know about SelectionDAG.

[chenwj]

@wenbos Could you explain why moving GetNumNodeResults up ahead solves the problem? I see one problem is Operator will be changed if it's SubClassOf("Intrinsic"), that might make GetNumNodeResults return the wrong result. I don't know if your patch is the right fix, although it works.

[wenbos]

This comment was removed by wenbos.

[wenbos]

In D32280#740713, @chenwj wrote:

@wenbos Could you explain why moving GetNumNodeResults up ahead solves the problem? I see one problem is Operator will be changed if it's SubClassOf("Intrinsic"), that might make GetNumNodeResults return the wrong result. I don't know if your patch is the right fix, although it works.

@chenwj Here is source code of how intrinsics SDNode for tablegen are defined. Intrinsics are hard-coded to have zero or one output. Check def for SDTypeProfile.
In TargetSelectionDAG.td:

// Nodes for intrinsics, you should use the intrinsic itself and let tblgen use
// these internally.  Don't reference these directly.
def intrinsic_void : SDNode<"ISD::INTRINSIC_VOID",
                            SDTypeProfile<0, -1, [SDTCisPtrTy<0>]>,
                            [SDNPHasChain]>;
def intrinsic_w_chain : SDNode<"ISD::INTRINSIC_W_CHAIN",
                               SDTypeProfile<1, -1, [SDTCisPtrTy<1>]>,
                               [SDNPHasChain]>;
def intrinsic_wo_chain : SDNode<"ISD::INTRINSIC_WO_CHAIN",
                                SDTypeProfile<1, -1, [SDTCisPtrTy<1>]>, []>;

[tim.schmielau]

I tried to mark this patch as a duplicate of the merged https://reviews.llvm.org/D32888 and ideally close it as such, but could not figure out how.

[chenwj]

Maybe you can close the patch manually?

Regards,
chenwj

Tim Schmielau via Phabricator <[e-mail]> 於 2022年1月8日 週六
上午4:18寫道：

tim.schmielau added a comment.

I tried to mark this patch as a duplicate of the merged
https://reviews.llvm.org/D32888 and ideally close it as such, but could
not figure out how.

Repository:

rL LLVM

CHANGES SINCE LAST ACTION

https://reviews.llvm.org/D32280/new/

https://reviews.llvm.org/D32280

[tim.schmielau]

This is my first activity on reviews.llvm.org, so I might just be lacking suitable permissions - I still don't see any way to close.
Thanks!
Tim

utils/TableGen/CodeGenDAGPatterns.cpp

TreePatternNode *TreePattern::ParseTreePattern(Init *TheInit, StringRef OpName){
   }
 
   std::vector<TreePatternNode*> Children;
 
   // Parse all the operands.
   for (unsigned i = 0, e = Dag->getNumArgs(); i != e; ++i)
     Children.push_back(ParseTreePattern(Dag->getArg(i), Dag->getArgNameStr(i)));
 
+  unsigned NumResults = GetNumNodeResults(Operator, CDP);
+
   // If the operator is an intrinsic, then this is just syntactic sugar for for
   // (intrinsic_* <number>, ..children..).  Pick the right intrinsic node, and
   // convert the intrinsic name to a number.
   if (Operator->isSubClassOf("Intrinsic")) {
     const CodeGenIntrinsic &Int = getDAGPatterns().getIntrinsic(Operator);
     unsigned IID = getDAGPatterns().getIntrinsicID(Operator)+1;
 
     // If this intrinsic returns void, it must have side-effects and thus a
for (unsigned i = 0; i < Children.size(); ++i) {
         if (PrevOp->getValue() != OperandId)
           error("All ComplexPattern operands must appear consistently: "
                 "in the same order in just one ComplexPattern instance.");
       } else
         ComplexPatternOperands[Child->getName()] = OperandId;
     }
   }
 
-  unsigned NumResults = GetNumNodeResults(Operator, CDP);
   TreePatternNode *Result = new TreePatternNode(Operator, Children, NumResults);
   Result->setName(OpName);
 
   if (Dag->getName()) {
     assert(Result->getName().empty());
     Result->setName(Dag->getNameStr());
   }
   return Result;