1 files changed, 137 insertions, 0 deletions
diff --git a/backend/lib/Target/RISCV/RISCVFunctionInfo.cpp b/backend/lib/Target/RISCV/RISCVFunctionInfo.cpp
new file mode 100644
index 0000000..f25bb8c
--- /dev/null
+++ b/backend/lib/Target/RISCV/RISCVFunctionInfo.cpp
@@ -0,0 +1,137 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "rcc/Target/RISCV/RISCVFunctionInfo.h"
+
+#include "rcc/CodeGen/TargetMIRTextInfo.h"
+
+#include <bit>
+#include <charconv>
+#include <cstddef>
+#include <cstdint>
+#include <span>
+#include <string>
+#include <string_view>
+#include <system_error>
+#include <utility>
+#include <vector>
+
+namespace rcc::riscv {
+namespace {
+
+[[nodiscard]] Expected<std::int32_t> parseSignedField(const MIRTargetNode &Node,
+                                                      std::string_view Name) {
+  if (Node.Kind != MIRTargetNodeKind::Scalar)
+    return makeUnexpected(ErrorCode::ParseError,
+                          "RISC-V machineFunctionInfo field '" + std::string(Name) +
+                              "' must be a scalar");
+  std::int32_t Value = 0;
+  const auto Result =
+      std::from_chars(Node.Scalar.data(), Node.Scalar.data() + Node.Scalar.size(), Value, 10);
+  if (Result.ec != std::errc{} || Result.ptr != Node.Scalar.data() + Node.Scalar.size()) {
+    return makeUnexpected(ErrorCode::ParseError,
+                          "RISC-V machineFunctionInfo field '" + std::string(Name) +
+                              "' must be a 32-bit signed integer");
+  }
+  return Value;
+}
+
+[[nodiscard]] Expected<TargetFunctionState> parseFunctionInfo(const MIRTargetNode &Node) {
+  if (Node.Kind != MIRTargetNodeKind::Mapping)
+    return makeUnexpected(ErrorCode::ParseError,
+                          "RISC-V machineFunctionInfo must be a mapping");
+
+  std::int32_t VarArgsFrameIndex = 0;
+  std::int32_t VarArgsSaveSize = 0;
+  for (const MIRTargetMappingEntry &Entry : Node.Mapping) {
+    if (Entry.Key == "varArgsFrameIndex") {
+      auto Value = parseSignedField(Entry.Value, Entry.Key);
+      if (!Value)
+        return std::unexpected(Value.error());
+      VarArgsFrameIndex = *Value;
+      continue;
+    }
+    if (Entry.Key == "varArgsSaveSize") {
+      auto Value = parseSignedField(Entry.Value, Entry.Key);
+      if (!Value)
+        return std::unexpected(Value.error());
+      VarArgsSaveSize = *Value;
+      continue;
+    }
+    return makeUnexpected(ErrorCode::ParseError,
+                          "unknown RISC-V machineFunctionInfo field '" + Entry.Key + "'");
+  }
+  return TargetFunctionState::create(
+      RISCVFunctionInfo(VarArgsFrameIndex, VarArgsSaveSize));
+}
+
+[[nodiscard]] Expected<MIRTargetNode>
+printFunctionInfo(const TargetFunctionState &State) {
+  const auto *Info = State.getIf<RISCVFunctionInfo>();
+  if (Info == nullptr)
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "target function state is not RISC-V function information");
+  std::vector<MIRTargetMappingEntry> Entries;
+  Entries.push_back({"varArgsFrameIndex",
+                     MIRTargetNode::scalar(std::to_string(Info->varArgsFrameIndex()))});
+  Entries.push_back({"varArgsSaveSize",
+                     MIRTargetNode::scalar(std::to_string(Info->varArgsSaveSize()))});
+  return MIRTargetNode::mapping(std::move(Entries));
+}
+
+void appendWord(std::vector<std::byte> &Payload, std::int32_t Value) {
+  const std::uint32_t Bits = std::bit_cast<std::uint32_t>(Value);
+  for (std::uint32_t Shift = 0; Shift != 32; Shift += 8)
+    Payload.push_back(static_cast<std::byte>((Bits >> Shift) & 0xFFU));
+}
+
+[[nodiscard]] std::int32_t readWord(std::span<const std::byte> Payload,
+                                    std::size_t Offset) noexcept {
+  std::uint32_t Bits = 0;
+  for (std::uint32_t Byte = 0; Byte != 4; ++Byte) {
+    Bits |= std::to_integer<std::uint32_t>(Payload[Offset + Byte]) << (Byte * 8U);
+  }
+  return std::bit_cast<std::int32_t>(Bits);
+}
+
+} // namespace
+
+Expected<void> RISCVFunctionInfo::verify() const {
+  return {};
+}
+
+Expected<RISCVFunctionInfo>
+RISCVFunctionInfo::clone(const MachineFunctionCloneContext &) const {
+  return RISCVFunctionInfo(VarArgsFrameIndex, VarArgsSaveSize);
+}
+
+std::string RISCVFunctionInfo::print() const {
+  return "riscv-varargs:" + std::to_string(VarArgsFrameIndex) + ":" +
+         std::to_string(VarArgsSaveSize);
+}
+
+Expected<std::vector<std::byte>> RISCVFunctionInfo::encode() const {
+  std::vector<std::byte> Payload;
+  Payload.reserve(8);
+  appendWord(Payload, VarArgsFrameIndex);
+  appendWord(Payload, VarArgsSaveSize);
+  return Payload;
+}
+
+Expected<RISCVFunctionInfo>
+RISCVFunctionInfo::decode(std::uint32_t Version, std::span<const std::byte> Payload) {
+  if (Version != schemaVersion())
+    return makeUnexpected(ErrorCode::ParseError,
+                          "unsupported RISC-V function-info schema version");
+  if (Payload.size() != 8)
+    return makeUnexpected(ErrorCode::ParseError,
+                          "RISC-V function-info payload must contain eight bytes");
+  return RISCVFunctionInfo(readWord(Payload, 0), readWord(Payload, 4));
+}
+
+void configureFunctionInfoMIRSchema(TargetMIRTextInfoDesc &Description) {
+  Description.FunctionStateType = RISCVFunctionInfo::stableTypeID();
+  Description.ParseFunctionState = parseFunctionInfo;
+  Description.PrintFunctionState = printFunctionInfo;
+}
+
+} // namespace rcc::riscv