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TableGen: Allow conditional instruction pattern in multiclass.
Define a 'null_frag' SDPatternOperator node, which if referenced in an instruction Pattern, results in the pattern being collapsed to be as-if '[]' had been specified instead. This allows supporting a multiclass definition where some instaniations have ISel patterns associated and others do not. For example, multiclass myMulti<RegisterClass rc, SDPatternOperator OpNode = null_frag> { def _x : myI<(outs rc:), (ins rc:), []>; def _r : myI<(outs rc:), (ins rc:), [(set rc:, (OpNode rc:))]>; } defm foo : myMulti<GRa, not>; defm bar : myMulti<GRb>; git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160333 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -595,6 +595,13 @@ def not : PatFrag<(ops node:$in), (xor node:$in, -1)>;
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def vnot : PatFrag<(ops node:$in), (xor node:$in, immAllOnesV)>;
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def ineg : PatFrag<(ops node:$in), (sub 0, node:$in)>;
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// null_frag - The null pattern operator is used in multiclass instantiations
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// which accept an SDPatternOperator for use in matching patterns for internal
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// definitions. When expanding a pattern, if the null fragment is referenced
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// in the expansion, the pattern is discarded and it is as-if '[]' had been
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// specified. This allows multiclasses to have the isel patterns be optional.
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def null_frag : SDPatternOperator;
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// load fragments.
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def unindexedload : PatFrag<(ops node:$ptr), (ld node:$ptr), [{
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return cast<LoadSDNode>(N)->getAddressingMode() == ISD::UNINDEXED;
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@ -2520,6 +2520,37 @@ static void InferFromPattern(const CodeGenInstruction &Inst,
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IsVariadic = true; // Can warn if we want.
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}
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/// hasNullFragReference - Return true if the DAG has any reference to the
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/// null_frag operator.
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static bool hasNullFragReference(DagInit *DI) {
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DefInit *OpDef = dynamic_cast<DefInit*>(DI->getOperator());
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if (!OpDef) return false;
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Record *Operator = OpDef->getDef();
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// If this is the null fragment, return true.
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if (Operator->getName() == "null_frag") return true;
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// If any of the arguments reference the null fragment, return true.
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for (unsigned i = 0, e = DI->getNumArgs(); i != e; ++i) {
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DagInit *Arg = dynamic_cast<DagInit*>(DI->getArg(i));
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if (Arg && hasNullFragReference(Arg))
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return true;
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}
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return false;
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}
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/// hasNullFragReference - Return true if any DAG in the list references
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/// the null_frag operator.
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static bool hasNullFragReference(ListInit *LI) {
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for (unsigned i = 0, e = LI->getSize(); i != e; ++i) {
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DagInit *DI = dynamic_cast<DagInit*>(LI->getElement(i));
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assert(DI && "non-dag in an instruction Pattern list?!");
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if (hasNullFragReference(DI))
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return true;
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}
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return false;
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}
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/// ParseInstructions - Parse all of the instructions, inlining and resolving
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/// any fragments involved. This populates the Instructions list with fully
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/// resolved instructions.
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@ -2534,8 +2565,11 @@ void CodeGenDAGPatterns::ParseInstructions() {
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// If there is no pattern, only collect minimal information about the
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// instruction for its operand list. We have to assume that there is one
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// result, as we have no detailed info.
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if (!LI || LI->getSize() == 0) {
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// result, as we have no detailed info. A pattern which references the
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// null_frag operator is as-if no pattern were specified. Normally this
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// is from a multiclass expansion w/ a SDPatternOperator passed in as
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// null_frag.
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if (!LI || LI->getSize() == 0 || hasNullFragReference(LI)) {
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std::vector<Record*> Results;
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std::vector<Record*> Operands;
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