[Mlir-commits] [mlir] [MLIR][LLVMIR] Add support for intrinsics with metadata arguments (PR #200308)

[Andy Kaylor]

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@@ -149,6 +150,72 @@ static LogicalResult convertInstructionImpl(OpBuilder &odsBuilder,
   return failure();
 }
 
+/// Depth-first conversion of the metadata node `md` to the matching LLVM
+/// dialect metadata attribute. Returns a null attribute for shapes that the
+/// dialect's metadata-attribute hierarchy does not currently model. `path`
+/// holds the metadata nodes on the current depth-first search path. Cyclic
+/// metadata graphs are valid in LLVM IR, but they cannot be expressed by the
+/// immutable, structurally-uniqued metadata attributes built here. The `path`
+/// set lets the traversal recognize such a back-edge and bail out. `attrMap`
+/// caches the attributes of fully converted nodes so that shared subgraphs
+/// are visited only once.
+static Attribute
+convertMetadataToAttrImpl(MLIRContext *ctx, const llvm::Metadata *md,
+                          SmallPtrSetImpl<const llvm::Metadata *> &path,
+                          DenseMap<const llvm::Metadata *, Attribute> &attrMap) {
+  if (!md)
+    return {};
+  if (auto *mdStr = dyn_cast<llvm::MDString>(md))
+    return MDStringAttr::get(ctx, StringAttr::get(ctx, mdStr->getString()));
+  if (auto *cam = dyn_cast<llvm::ConstantAsMetadata>(md)) {
+    auto *ci = dyn_cast<llvm::ConstantInt>(cam->getValue());
+    if (!ci)
+      return {};
+    auto intType = IntegerType::get(ctx, ci->getBitWidth());
+    return MDConstantAttr::get(ctx, IntegerAttr::get(intType, ci->getValue()));
+  }
+  if (auto *vam = dyn_cast<llvm::ValueAsMetadata>(md)) {
+    auto *fn = dyn_cast<llvm::Function>(vam->getValue());
+    if (!fn)
+      return {};
+    return MDFuncAttr::get(ctx, FlatSymbolRefAttr::get(ctx, fn->getName()));
+  }
+  if (auto *node = dyn_cast<llvm::MDNode>(md)) {
+    if (Attribute cached = attrMap.lookup(node))
----------------
andykaylor wrote:

That's a relatively simple change, but I'm not sure it gains us much. Right now, this is only saving `MDNode` metadata in the map, so the most this would save us is a handful of `dyn_cast` checks. We could, in theory, add the string, constant, and value metadata to the map, but those don't have leafs and the real purpose of this map is to avoid blowing up compile time if we ever hit metadata with a deep tree with repeated references.

https://github.com/llvm/llvm-project/pull/200308