[llvm] [TableGen] Add a backend generating SDNode descriptions (PR #123002)

[Matt Arsenault via llvm-commits]

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@@ -0,0 +1,369 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "Basic/SequenceToOffsetTable.h"
+#include "Common/CodeGenDAGPatterns.h" // For SDNodeInfo.
+#include "llvm/Support/CommandLine.h"
+#include "llvm/TableGen/Error.h"
+#include "llvm/TableGen/StringToOffsetTable.h"
+#include "llvm/TableGen/TableGenBackend.h"
+
+using namespace llvm;
+
+static cl::OptionCategory SDNodeInfoEmitterCat("Options for -gen-sdnode-info");
+
+static cl::opt<std::string> TargetSDNodeNamespace(
+    "sdnode-namespace", cl::cat(SDNodeInfoEmitterCat),
+    cl::desc("Specify target SDNode namespace (default=<Target>ISD)"));
+
+static cl::opt<bool> WarnOnSkippedNodes(
+    "warn-on-skipped-nodes", cl::cat(SDNodeInfoEmitterCat),
+    cl::desc("Explain why a node was skipped (default=true)"), cl::init(true));
+
+namespace {
+
+class SDNodeInfoEmitter {
+  const RecordKeeper &RK;
+  const CodeGenTarget Target;
+  std::vector<SDNodeInfo> AllNodes;
+  std::map<StringRef, SmallVector<const SDNodeInfo *, 2>> TargetNodesByName;
+
+public:
+  explicit SDNodeInfoEmitter(const RecordKeeper &RK);
+
+  void run(raw_ostream &OS) const;
+
+private:
+  void emitEnum(raw_ostream &OS) const;
+
+  std::vector<unsigned> emitNodeNames(raw_ostream &OS) const;
+
+  std::vector<std::pair<unsigned, unsigned>>
+  emitTypeConstraints(raw_ostream &OS) const;
+
+  void emitDescs(raw_ostream &OS) const;
+};
+
+} // namespace
+
+static bool haveCompatibleDescriptions(const SDNodeInfo *N1,
+                                       const SDNodeInfo *N2) {
+  // Number of results/operands must match.
+  if (N1->getNumResults() != N2->getNumResults() ||
+      N1->getNumOperands() != N2->getNumOperands())
+    return false;
+
+  // Flags must match.
+  if (N1->isStrictFP() != N2->isStrictFP() ||
+      N1->getTSFlags() != N2->getTSFlags())
+    return false;
+
+  // We're only interested in a subset of node properties. Properties like
+  // SDNPAssociative and SDNPCommutative do not impose constraints on nodes,
+  // and sometimes differ between nodes sharing the same enum name.
+  constexpr unsigned PropMask = (1 << SDNPHasChain) | (1 << SDNPOutGlue) |
+                                (1 << SDNPInGlue) | (1 << SDNPOptInGlue) |
+                                (1 << SDNPMemOperand) | (1 << SDNPVariadic);
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arsenm wrote:

At some point we should probably upgrade the enum to a bitmask enum

https://github.com/llvm/llvm-project/pull/123002