1 files changed, 89 insertions, 0 deletions
diff --git a/tools/frr-llvm-debuginfo.cpp b/tools/frr-llvm-debuginfo.cpp
new file mode 100644
index 0000000..16ad18b
--- /dev/null
+++ b/tools/frr-llvm-debuginfo.cpp
@@ -0,0 +1,89 @@
+// SPDX-License-Identifier: Unlicense
+
+#include <llvm-c/BitReader.h>
+#include <llvm-c/BitWriter.h>
+#include <llvm-c/Core.h>
+#include <llvm-c/DebugInfo.h>
+
+#include <llvm/IR/Module.h>
+#include <llvm/IR/Value.h>
+#include <llvm/IR/Type.h>
+#include <llvm/IR/DebugInfo.h>
+#include <llvm/IR/DebugInfoMetadata.h>
+#include <llvm/Support/raw_ostream.h>
+
+#include <map>
+
+#include "frr-llvm-debuginfo.h"
+
+/* llvm::DebugInfoFinder is unfortunately not exposed in the llvm-c API... */
+
+struct dbginfo {
+	llvm::DebugInfoFinder finder;
+	std::map<std::string, llvm::DICompositeType *> tab;
+};
+
+struct dbginfo *dbginfo_load(LLVMModuleRef _mod)
+{
+	llvm::Module *mod = llvm::unwrap(_mod);
+	struct dbginfo *info = new dbginfo();
+
+	info->finder.processModule(*mod);
+
+	for (auto ty : info->finder.types()) {
+		if (ty->getMetadataID() != llvm::Metadata::DICompositeTypeKind)
+			continue;
+
+		llvm::DICompositeType *cty = (llvm::DICompositeType *)ty;
+		/* empty forward declarations aka "struct foobar;" */
+		if (cty->getElements().size() == 0)
+			continue;
+
+		info->tab.emplace(std::move(ty->getName().str()), cty);
+	}
+
+	return info;
+}
+
+bool dbginfo_struct_member(struct dbginfo *info, LLVMTypeRef _typ,
+			   unsigned long long idx, char **struct_name,
+			   char **member_name)
+{
+	*struct_name = NULL;
+	*member_name = NULL;
+
+	llvm::Type *typ = llvm::unwrap(_typ);
+
+	if (!typ->isStructTy())
+		return false;
+
+	llvm::StructType *styp = (llvm::StructType *)typ;
+	auto sname = styp->getStructName();
+
+	if (!sname.startswith("struct."))
+		return false;
+	sname = sname.drop_front(7);
+
+	size_t dot = sname.find_last_of(".");
+	if (dot != sname.npos)
+		sname = sname.take_front(dot);
+
+	auto item = info->tab.find(sname.str());
+	if (item == info->tab.end())
+		return false;
+
+	auto elements = item->second->getElements();
+	if (idx >= elements.size())
+		return false;
+
+	auto elem = elements[idx];
+
+	if (elem->getMetadataID() != llvm::Metadata::DIDerivedTypeKind)
+		return false;
+
+	llvm::DIDerivedType *dtyp = (llvm::DIDerivedType *)elem;
+
+	*struct_name = strdup(sname.str().c_str());
+	*member_name = strdup(dtyp->getName().str().c_str());
+	return true;
+}