1 files changed, 234 insertions, 0 deletions
diff --git a/backend/lib/CodeGen/MachineFrameInfo.cpp b/backend/lib/CodeGen/MachineFrameInfo.cpp
new file mode 100644
index 0000000..58eab00
--- /dev/null
+++ b/backend/lib/CodeGen/MachineFrameInfo.cpp
@@ -0,0 +1,234 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "rcc/CodeGen/MachineFrameInfo.h"
+
+#include <cstddef>
+#include <cstdint>
+#include <limits>
+#include <unordered_set>
+#include <utility>
+
+namespace rcc {
+
+Expected<StackID> StackID::targetStack(std::uint32_t Value) {
+  if (Value < FirstTargetStackValue) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "target stack ID must not overlap a built-in stack ID");
+  }
+  return StackID(Value);
+}
+
+bool StackObject::isSpill() const noexcept {
+  const StackObjectDesc *Desc = description();
+  if (Desc == nullptr)
+    return false;
+  return Desc->Kind == StackObjectKind::SpillSlot || Desc->Kind == StackObjectKind::CalleeSaved ||
+         Desc->Kind == StackObjectKind::EmergencySpill;
+}
+
+bool StackObject::isFixed() const noexcept {
+  const StackObjectDesc *Desc = description();
+  return Desc != nullptr && Desc->Kind == StackObjectKind::FixedABI;
+}
+
+bool StackObject::isVariableSized() const noexcept {
+  const StackObjectDesc *Desc = description();
+  return Desc != nullptr && (Desc->Kind == StackObjectKind::VariableSized ||
+                             Desc->Kind == StackObjectKind::DynamicAlloca);
+}
+
+Expected<void> MachineFrameInfo::verifyDescription(const StackObjectDesc &Description) {
+  if (Description.Kind >= StackObjectKind::Count)
+    return makeUnexpected(ErrorCode::InvalidArgument, "stack object kind is invalid");
+  if (!Description.Stack.isValid())
+    return makeUnexpected(ErrorCode::InvalidArgument, "stack object has an invalid stack ID");
+
+  const bool IsVariable = Description.Kind == StackObjectKind::VariableSized ||
+                          Description.Kind == StackObjectKind::DynamicAlloca;
+  if (IsVariable) {
+    if (Description.Size || Description.Offset) {
+      return makeUnexpected(ErrorCode::InvalidArgument,
+                            "variable-sized stack objects cannot have a fixed size or offset");
+    }
+  } else if (!Description.Size || *Description.Size == 0) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "fixed-size stack objects require a nonzero size");
+  }
+
+  if (Description.Kind == StackObjectKind::FixedABI && !Description.Offset) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "fixed ABI stack objects require a fixed offset");
+  }
+  if (Description.Kind == StackObjectKind::Target && !Description.Stack.isTargetStack() &&
+      Description.TargetFlags == 0) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "target stack objects require a target stack ID or nonzero target flags");
+  }
+
+  std::unordered_set<MachineInstrStableID> LifetimeBoundaries;
+  for (const StackObjectLifetimeRange &Range : Description.Lifetime) {
+    if (!Range.Begin.isValid() || !Range.End.isValid() || Range.Begin == Range.End) {
+      return makeUnexpected(ErrorCode::InvalidArgument,
+                            "stack object lifetime boundaries must be valid and distinct");
+    }
+    if (!LifetimeBoundaries.insert(Range.Begin).second ||
+        !LifetimeBoundaries.insert(Range.End).second) {
+      return makeUnexpected(ErrorCode::InvalidArgument,
+                            "stack object lifetime boundaries must not be reused");
+    }
+  }
+  return {};
+}
+
+Expected<FrameIndex> MachineFrameInfo::createObject(StackObjectDesc Description) {
+  if (Frozen)
+    return makeUnexpected(ErrorCode::InvalidArgument, "frozen frame cannot create stack objects");
+  auto DescriptionResult = verifyDescription(Description);
+  if (!DescriptionResult)
+    return std::unexpected(DescriptionResult.error());
+  if (Objects.size() > std::numeric_limits<std::uint32_t>::max()) {
+    return makeUnexpected(ErrorCode::Unsupported, "stack object index space is exhausted");
+  }
+
+  const FrameIndex Index = FrameIndex::fromValue(static_cast<std::uint32_t>(Objects.size()));
+  Objects.push_back(StackObject(Index, std::move(Description)));
+  return Index;
+}
+
+Expected<StackObject *> MachineFrameInfo::mutableObject(FrameIndex Index) {
+  if (Frozen)
+    return makeUnexpected(ErrorCode::InvalidArgument, "frozen frame cannot modify stack objects");
+  if (Index.value() >= Objects.size())
+    return makeUnexpected(ErrorCode::InvalidArgument, "stack object index is out of range");
+  StackObject &Object = Objects[Index.value()];
+  if (Object.isTombstone())
+    return makeUnexpected(ErrorCode::InvalidArgument, "stack object index is a tombstone");
+  return &Object;
+}
+
+Expected<void> MachineFrameInfo::updateObject(FrameIndex Index, StackObjectDesc Description) {
+  auto DescriptionResult = verifyDescription(Description);
+  if (!DescriptionResult)
+    return std::unexpected(DescriptionResult.error());
+  auto Object = mutableObject(Index);
+  if (!Object)
+    return std::unexpected(Object.error());
+  (*Object)->Description.emplace<StackObjectDesc>(std::move(Description));
+  return {};
+}
+
+Expected<void> MachineFrameInfo::setObjectOffset(FrameIndex Index, std::int64_t Offset) {
+  auto Object = mutableObject(Index);
+  if (!Object)
+    return std::unexpected(Object.error());
+  StackObjectDesc *CurrentDescription = std::get_if<StackObjectDesc>(&(*Object)->Description);
+  if (CurrentDescription == nullptr) {
+    return makeUnexpected(ErrorCode::InternalError,
+                          "live stack object unexpectedly lacks a description");
+  }
+  StackObjectDesc Description = *CurrentDescription;
+  if ((*Object)->isVariableSized()) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "variable-sized stack object cannot have a fixed offset");
+  }
+  Description.Offset = Offset;
+  (*Object)->Description.emplace<StackObjectDesc>(std::move(Description));
+  return {};
+}
+
+Expected<void> MachineFrameInfo::markObjectDead(FrameIndex Index) {
+  auto Object = mutableObject(Index);
+  if (!Object)
+    return std::unexpected(Object.error());
+  StackObjectDesc *Description = std::get_if<StackObjectDesc>(&(*Object)->Description);
+  if (Description == nullptr) {
+    return makeUnexpected(ErrorCode::InternalError,
+                          "live stack object unexpectedly lacks a description");
+  }
+  Description->IsDead = true;
+  return {};
+}
+
+Expected<void> MachineFrameInfo::eraseObject(FrameIndex Index) {
+  auto Object = mutableObject(Index);
+  if (!Object)
+    return std::unexpected(Object.error());
+  (*Object)->Description.emplace<std::monostate>();
+  return {};
+}
+
+const StackObject *MachineFrameInfo::object(FrameIndex Index) const noexcept {
+  if (Index.value() >= Objects.size() || Objects[Index.value()].isTombstone())
+    return nullptr;
+  return &Objects[Index.value()];
+}
+
+std::size_t MachineFrameInfo::liveObjectCount() const noexcept {
+  std::size_t Count = 0;
+  for (const StackObject &Object : Objects) {
+    if (!Object.isTombstone())
+      ++Count;
+  }
+  return Count;
+}
+
+Expected<void> MachineFrameInfo::setMaxCallFrameSize(std::uint64_t Size) {
+  if (Frozen)
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "frozen frame cannot change its maximum call-frame size");
+  MaxCallFrameSize = Size;
+  return {};
+}
+
+Expected<void> MachineFrameInfo::freeze(std::uint64_t Size, Alignment Align) {
+  if (Frozen)
+    return makeUnexpected(ErrorCode::InvalidArgument, "frame layout is already frozen");
+  for (const StackObject &Object : Objects) {
+    if (Object.isTombstone() || Object.isVariableSized())
+      continue;
+    if (!Object.description()->Offset) {
+      return makeUnexpected(ErrorCode::VerificationError,
+                            "fixed-size stack object is missing its final offset");
+    }
+  }
+  if (Size % Align.bytes() != 0) {
+    return makeUnexpected(ErrorCode::InvalidArgument,
+                          "static stack size must be aligned to the stack alignment");
+  }
+
+  StaticStackSize = Size;
+  StackAlign = Align;
+  Frozen = true;
+  return {};
+}
+
+Expected<void> MachineFrameInfo::verify() const {
+  for (std::size_t Position = 0; Position < Objects.size(); ++Position) {
+    const StackObject &Object = Objects[Position];
+    if (Object.index() != FrameIndex::fromValue(static_cast<std::uint32_t>(Position))) {
+      return makeUnexpected(ErrorCode::VerificationError,
+                            "stack object index does not match its stable table position");
+    }
+    if (Object.isTombstone())
+      continue;
+    auto DescriptionResult = verifyDescription(*Object.description());
+    if (!DescriptionResult)
+      return std::unexpected(DescriptionResult.error());
+    if (Frozen && !Object.isVariableSized() && !Object.description()->Offset) {
+      return makeUnexpected(ErrorCode::VerificationError,
+                            "frozen fixed-size stack object has no final offset");
+    }
+  }
+
+  if (Frozen != StaticStackSize.has_value()) {
+    return makeUnexpected(ErrorCode::VerificationError,
+                          "frame frozen state and static stack size are inconsistent");
+  }
+  if (Frozen && *StaticStackSize % StackAlign.bytes() != 0) {
+    return makeUnexpected(ErrorCode::VerificationError,
+                          "frozen static stack size violates stack alignment");
+  }
+  return {};
+}
+
+} // namespace rcc