[Handshake] Buffering properties improvements

lucas-rami · lucas-rami · commit 9be49b914f82 · 2023-08-25T14:00:51.000+02:00
This commit slightly changes the methods of the ChannelBufProps struct,
removing those that do not appear to be immediately useful and, on the
contrary, adding immediately useful ones.
diff --git a/include/circt/Dialect/Handshake/HandshakeOps.h b/include/circt/Dialect/Handshake/HandshakeOps.h
@@ -86,25 +86,12 @@ struct ChannelBufProps {
                   unsigned minOpaque = 0,
                   std::optional<unsigned> maxOpaque = std::nullopt);
 
-  /// Produces channel buffering properties based on the current ones minus a
-  /// particular number of transparent slots. Returns std::nullopt if the
-  /// provided number of slots is greater than the maximum number of allowed
-  /// slots (indicating that properties can't be satisfied).
-  std::optional<ChannelBufProps> subtractTrans(unsigned numSlots);
-
-  /// Produces channel buffering properties based on the current ones minus a
-  /// particular number of opaque slots. Returns std::nullopt if the
-  /// provided number of slots is greater than the maximum number of allowed
-  /// slots (indicating that properties can't be satisfied).
-  std::optional<ChannelBufProps> subtractOpaque(unsigned numSlots);
+  /// Determines whether these buffering properties are satisfiable i.e.,
+  /// whether it's possible to create a buffer that respects them.
+  bool isSatisfiable() const;
 
   /// Computes member-wise equality.
-  inline bool operator==(const ChannelBufProps &rhs) const {
-    return (this->minTrans == rhs.minTrans) &&
-           (this->maxTrans == rhs.maxTrans) &&
-           (this->minOpaque == rhs.minOpaque) &&
-           (this->maxOpaque == rhs.maxOpaque);
-  }
+  bool operator==(const ChannelBufProps &rhs) const;
 };
 
 /// Custom specialization of llvm::hash_value for ChannelBufProps. Converts the
@@ -114,6 +101,12 @@ struct ChannelBufProps {
 llvm::hash_code hash_value(const ChannelBufProps &props);
 } // namespace dynamatic
 
+/// Prints the buffering properties as two closed or semi-open intervals
+/// (depending on whether maximum are defined), one for tranparent slots and one
+/// for opaque slots.
+std::ostream &operator<<(std::ostream &os,
+                         const dynamatic::ChannelBufProps &props);
+
 namespace mlir {
 namespace OpTrait {
 template <typename ConcreteType>
diff --git a/lib/Dialect/Handshake/HandshakeOps.cpp b/lib/Dialect/Handshake/HandshakeOps.cpp
@@ -1895,30 +1895,28 @@ ChannelBufProps::ChannelBufProps(unsigned minTrans,
     : minTrans(minTrans), maxTrans(maxTrans), minOpaque(minOpaque),
       maxOpaque(maxOpaque){};
 
-std::optional<ChannelBufProps>
-ChannelBufProps::subtractTrans(unsigned numSlots) {
-  std::optional<unsigned> newMaxTrans;
-  if (maxTrans.has_value()) {
-    if (maxTrans.value() < numSlots)
-      return {};
-    newMaxTrans = maxTrans.value() - numSlots;
-  }
-
-  unsigned newMinTrans = minTrans < numSlots ? 0U : minTrans - numSlots;
-  return ChannelBufProps(newMinTrans, minTrans, minOpaque, maxOpaque);
-}
-
-std::optional<ChannelBufProps>
-ChannelBufProps::subtractOpaque(unsigned numSlots) {
-  std::optional<unsigned> newMaxOpaque;
-  if (maxOpaque.has_value()) {
-    if (maxOpaque.value() < numSlots)
-      return {};
-    newMaxOpaque = maxOpaque.value() - numSlots;
-  }
-
-  unsigned newMinOpaque = minOpaque < numSlots ? 0U : minOpaque - numSlots;
-  return ChannelBufProps(minTrans, maxTrans, newMinOpaque, newMaxOpaque);
+bool ChannelBufProps::isSatisfiable() const {
+  return (!maxTrans.has_value() || maxTrans.value() > minTrans) &&
+         (!maxOpaque.has_value() || maxOpaque.value() > minOpaque);
+}
+
+bool ChannelBufProps::operator==(const ChannelBufProps &rhs) const {
+  return (this->minTrans == rhs.minTrans) && (this->maxTrans == rhs.maxTrans) &&
+         (this->minOpaque == rhs.minOpaque) &&
+         (this->maxOpaque == rhs.maxOpaque);
+}
+
+std::ostream &operator<<(std::ostream &os, const ChannelBufProps &props) {
+  std::string maxTransStr = props.maxTrans.has_value()
+                                ? (std::to_string(props.maxTrans.value()) + "]")
+                                : "inf)";
+  std::string maxOpaqueStr =
+      props.maxOpaque.has_value()
+          ? (std::to_string(props.maxOpaque.value()) + "]")
+          : "inf)";
+  os << "T: [" << props.minTrans << ", " << maxTransStr << ", O: ["
+     << props.minOpaque << ", " << maxOpaqueStr;
+  return os;
 }
 
 llvm::hash_code dynamatic::hash_value(const ChannelBufProps &props) {
