[Synth] Add attribute for linear delay model and pass to approximate them from NLDM attr

include/circt/Dialect/Synth/CMakeLists.txt

@@ -12,6 +12,12 @@ add_circt_interface(SynthOpInterfaces)
 add_subdirectory(Transforms)
 
 set(LLVM_TARGET_DEFINITIONS Synth.td)
+
+mlir_tablegen(SynthEnums.h.inc -gen-enum-decls)
+mlir_tablegen(SynthEnums.cpp.inc -gen-enum-defs)
+add_public_tablegen_target(CIRCTSynthEnumsIncGen)
+add_dependencies(circt-headers CIRCTSynthEnumsIncGen)
+
 mlir_tablegen(SynthAttributes.h.inc -gen-attrdef-decls -attrdefs-dialect=synth)
 mlir_tablegen(SynthAttributes.cpp.inc -gen-attrdef-defs -attrdefs-dialect=synth)
 add_public_tablegen_target(CIRCTSynthAttrIncGen)

include/circt/Dialect/Synth/Synth.td

@@ -26,6 +26,7 @@ def Synth_Dialect : Dialect {
   let useDefaultAttributePrinterParser = 1;
 }
 
+include "circt/Dialect/Synth/SynthEnums.td"
 include "circt/Dialect/Synth/SynthAttributes.td"
 include "circt/Dialect/Synth/SynthOps.td"
 

include/circt/Dialect/Synth/SynthAttributes.h

@@ -9,6 +9,7 @@
 #ifndef CIRCT_DIALECT_SYNTH_SYNTHATTRIBUTES_H
 #define CIRCT_DIALECT_SYNTH_SYNTHATTRIBUTES_H
 
+#include "circt/Dialect/Synth/SynthEnums.h"
 #include "mlir/IR/Attributes.h"
 #include "mlir/IR/BuiltinAttributes.h"
 

include/circt/Dialect/Synth/SynthAttributes.td

@@ -12,6 +12,8 @@
 
 include "mlir/IR/AttrTypeBase.td"
 include "mlir/IR/DialectBase.td"
+include "mlir/IR/EnumAttr.td"
+include "circt/Dialect/Synth/SynthEnums.td"
 
 // A single resolved 2D NLDM lookup table. Values are stored in row-major order
 // with dimensions index1.size x index2.size.
@@ -45,5 +47,41 @@ def NLDMTimingArcAttr : AttrDef<Synth_Dialect, "NLDMTimingArc"> {
     "$riseTransition `,` $fallTransition `>`";
 }
 
+def PolarityAttr : AttrDef<Synth_Dialect, "Polarity"> {
+  let mnemonic = "polarity";
+  let summary = "Timing arc polarity";
+  let parameters = (ins
+    "PolarityKind":$value
+  );
+  let assemblyFormat = "`<` $value `>`";
+}
+
+def LinearTimingArcAttr : AttrDef<Synth_Dialect, "LinearTimingArc"> {
+  let mnemonic = "linear_timing_arc";
+  let summary = "A single simplified linear timing arc";
+  let parameters = (ins
+    "::mlir::StringAttr":$pin,
+    "::mlir::StringAttr":$relatedPin,
+    "int64_t":$intrinsic,
+    "int64_t":$sensitivity,
+    "PolarityAttr":$polarity
+  );
+  let assemblyFormat =
+    "`<` $pin `,` $relatedPin `,` $intrinsic `,` $sensitivity `,` "
+    "$polarity `>`";
+}
+
+def MappingCostAttr : AttrDef<Synth_Dialect, "MappingCost"> {
+  let mnemonic = "mapping_cost";
+  let summary = "Simplified timing and area cost for tech mapping";
+  let parameters = (ins
+    "::mlir::FloatAttr":$area,
+    "::mlir::ArrayAttr":$arcs,
+    "::mlir::DictionaryAttr":$inputCaps
+  );
+  let assemblyFormat =
+    "`<` `area` `=` $area `,` `arcs` `=` $arcs `,` "
+    "`input_caps` `=` $inputCaps `>`";
+}
 
 #endif // CIRCT_DIALECT_SYNTH_SYNTHATTRIBUTES_TD

include/circt/Dialect/Synth/SynthEnums.h

@@ -0,0 +1,17 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef CIRCT_DIALECT_SYNTH_SYNTHENUMS_H
+#define CIRCT_DIALECT_SYNTH_SYNTHENUMS_H
+
+#include "mlir/IR/BuiltinAttributes.h"
+#include "llvm/ADT/StringRef.h"
+
+#include "circt/Dialect/Synth/SynthEnums.h.inc"
+
+#endif // CIRCT_DIALECT_SYNTH_SYNTHENUMS_H

include/circt/Dialect/Synth/SynthEnums.td

@@ -0,0 +1,28 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines Synth dialect specific enums.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef CIRCT_DIALECT_SYNTH_SYNTHENUMS_TD
+#define CIRCT_DIALECT_SYNTH_SYNTHENUMS_TD
+
+include "mlir/IR/EnumAttr.td"
+
+let cppNamespace = "circt::synth" in {
+
+def Polarity_Positive : I32EnumAttrCase<"Positive", 0, "positive">;
+def Polarity_Negative : I32EnumAttrCase<"Negative", 1, "negative">;
+
+def PolarityKindAttr : I32EnumAttr<"PolarityKind", "timing arc polarity",
+  [Polarity_Positive, Polarity_Negative]>;
+
+}
+
+#endif // CIRCT_DIALECT_SYNTH_SYNTHENUMS_TD

integration_test/circt-synth/mapping-lec.mlir

@@ -15,29 +15,29 @@
 // COMB_MUL_LUT: c1 == c2
 
 // Set delay for binary and inv op to 5 so that others will be prioritized
-hw.module @and_inv(in %a : i1, in %b : i1, out result : i1) attributes {hw.techlib.info = {area = 1.0 : f64, delay = [[5], [5]]}} {
+hw.module @and_inv(in %a : i1, in %b : i1, out result : i1) attributes {synth.mapping_cost = #synth.mapping_cost<area = 1.0 : f64, arcs = [#synth.linear_timing_arc<"result", "a", 5, 0, #synth.polarity<positive>>, #synth.linear_timing_arc<"result", "b", 5, 0, #synth.polarity<positive>>], input_caps = {}>} {
     %0 = synth.aig.and_inv %a, %b : i1
     hw.output %0 : i1
 }
 
-hw.module @and_inv_n(in %a : i1, in %b : i1, out result : i1) attributes {hw.techlib.info = {area = 1.0 : f64, delay = [[5], [5]]}} {
+hw.module @and_inv_n(in %a : i1, in %b : i1, out result : i1) attributes {synth.mapping_cost = #synth.mapping_cost<area = 1.0 : f64, arcs = [#synth.linear_timing_arc<"result", "a", 5, 0, #synth.polarity<positive>>, #synth.linear_timing_arc<"result", "b", 5, 0, #synth.polarity<positive>>], input_caps = {}>} {
     %0 = synth.aig.and_inv not %a, %b : i1
     hw.output %0 : i1
 }
 
-hw.module @and_inv_nn(in %a : i1, in %b : i1, out result : i1) attributes {hw.techlib.info = {area = 1.0 : f64, delay = [[5], [5]]}} {
+hw.module @and_inv_nn(in %a : i1, in %b : i1, out result : i1) attributes {synth.mapping_cost = #synth.mapping_cost<area = 1.0 : f64, arcs = [#synth.linear_timing_arc<"result", "a", 5, 0, #synth.polarity<positive>>, #synth.linear_timing_arc<"result", "b", 5, 0, #synth.polarity<positive>>], input_caps = {}>} {
     %0 = synth.aig.and_inv not %a, not %b : i1
     hw.output %0 : i1
 }
 
-hw.module @nand_nand(in %a : i1, in %b : i1, in %c : i1, in %d: i1, out result : i1) attributes {hw.techlib.info = {area = 3.0 : f64, delay = [[1], [1], [1], [1]]}} {
+hw.module @nand_nand(in %a : i1, in %b : i1, in %c : i1, in %d: i1, out result : i1) attributes {synth.mapping_cost = #synth.mapping_cost<area = 3.0 : f64, arcs = [#synth.linear_timing_arc<"result", "a", 1, 0, #synth.polarity<positive>>, #synth.linear_timing_arc<"result", "b", 1, 0, #synth.polarity<positive>>, #synth.linear_timing_arc<"result", "c", 1, 0, #synth.polarity<positive>>, #synth.linear_timing_arc<"result", "d", 1, 0, #synth.polarity<positive>>], input_caps = {}>} {
     %0 = synth.aig.and_inv %a, %b : i1
     %1 = synth.aig.and_inv %c, %d : i1
     %2 = synth.aig.and_inv not %0, not %1 : i1
     hw.output %2 : i1
 }
 
-hw.module @some(in %a : i1, in %b : i1, out result : i1) attributes {hw.techlib.info = {area = 1.0 : f64, delay = [[1], [1]]}} {
+hw.module @some(in %a : i1, in %b : i1, out result : i1) attributes {synth.mapping_cost = #synth.mapping_cost<area = 1.0 : f64, arcs = [#synth.linear_timing_arc<"result", "a", 1, 0, #synth.polarity<positive>>, #synth.linear_timing_arc<"result", "b", 1, 0, #synth.polarity<positive>>], input_caps = {}>} {
     %0 = synth.aig.and_inv not %a, not %b : i1
     %1 = synth.aig.and_inv %a, %b : i1
     %2 = synth.aig.and_inv not %0, not %1 : i1

lib/Dialect/Synth/CMakeLists.txt

@@ -15,6 +15,7 @@ add_circt_dialect_library(CIRCTSynth
   DEPENDS
   MLIRSynthIncGen
   MLIRSynthOpInterfacesIncGen
+  CIRCTSynthEnumsIncGen
   CIRCTSynthAttrIncGen
 
   LINK_COMPONENTS

lib/Dialect/Synth/SynthDialect.cpp

@@ -9,6 +9,7 @@
 #include "circt/Dialect/Synth/SynthDialect.h"
 #include "circt/Dialect/HW/HWOps.h"
 #include "circt/Dialect/Synth/SynthAttributes.h"
+#include "circt/Dialect/Synth/SynthEnums.h"
 #include "circt/Dialect/Synth/SynthOps.h"
 #include "mlir/IR/DialectImplementation.h"
 
@@ -41,3 +42,5 @@ Operation *SynthDialect::materializeConstant(OpBuilder &builder,
 
 #define GET_ATTRDEF_CLASSES
 #include "circt/Dialect/Synth/SynthAttributes.cpp.inc"
+
+#include "circt/Dialect/Synth/SynthEnums.cpp.inc"

lib/Dialect/Synth/Transforms/TechMapper.cpp

@@ -12,18 +12,20 @@
 //
 // The pass uses a cut-based algorithm with priority cuts and NPN canonical
 // forms for efficient pattern matching. It processes HWModuleOp instances with
-// "hw.techlib.info" attributes as technology library patterns and maps
+// "synth.mapping_cost" attributes as technology library patterns and maps
 // non-library modules to optimal gate implementations based on area and timing
 // optimization strategies.
 //
 //===----------------------------------------------------------------------===//
 
 #include "circt/Dialect/HW/HWOps.h"
+#include "circt/Dialect/Synth/SynthAttributes.h"
 #include "circt/Dialect/Synth/Transforms/CutRewriter.h"
 #include "mlir/IR/Builders.h"
 #include "mlir/IR/Threading.h"
 #include "mlir/Support/WalkResult.h"
 #include "llvm/ADT/APInt.h"
+#include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/Support/Debug.h"
 #include <atomic>
@@ -188,48 +190,94 @@ struct TechMapperPass : public impl::TechMapperBase<TechMapperPass> {
     SmallVector<std::unique_ptr<CutRewritePattern>> libraryPatterns;
 
     unsigned maxInputSize = 0;
-    // Consider modules with the "hw.techlib.info" attribute as library
+    // Consider modules with the "synth.mapping_cost" attribute as library
     // modules.
-    // TODO: This attribute should be replaced with a more structured
-    // representation of technology library information. Specifically, we should
-    // have a dedicated operation for technology library.
     SmallVector<hw::HWModuleOp> nonLibraryModules;
     for (auto hwModule : module.getOps<hw::HWModuleOp>()) {
-      auto techInfo =
-          hwModule->getAttrOfType<DictionaryAttr>("hw.techlib.info");
-      if (!techInfo) {
-        // If the module does not have the techlib info, it is not a library
-        // TODO: Run mapping only when the module is under the specific
-        // hierarchy.
+
+      auto mappingCost =
+          hwModule->getAttrOfType<MappingCostAttr>("synth.mapping_cost");
+      if (!mappingCost) {
         nonLibraryModules.push_back(hwModule);
         continue;
       }
 
-      // Get area and delay attributes
-      auto areaAttr = techInfo.getAs<FloatAttr>("area");
-      auto delayAttr = techInfo.getAs<ArrayAttr>("delay");
-      if (!areaAttr || !delayAttr) {
-        mlir::emitError(hwModule.getLoc())
-            << "Library module " << hwModule.getModuleName()
-            << " must have 'area'(float) and 'delay' (2d array to represent "
-               "input-output pair delay) attributes";
+      double area = mappingCost.getArea().getValue().convertToDouble();
+
+      StringAttr outputName;
+      hw::ModulePortInfo ports(hwModule.getPortList());
+      for (const auto &port : ports.getOutputs()) {
+        if (outputName) {
+          hwModule.emitError(
+              "Modules with multiple outputs are not supported yet");
+          signalPassFailure();
+          return;
+        }
+        outputName = port.name;
+      }
+      if (!outputName) {
+        hwModule.emitError("expected library module to have an output");
         signalPassFailure();
         return;
       }
 
-      double area = areaAttr.getValue().convertToDouble();
+      llvm::DenseMap<StringAttr, DelayType> delayByInput;
+      for (auto attr : mappingCost.getArcs()) {
+        auto arc = cast<LinearTimingArcAttr>(attr);
+        if (!arc) {
+          hwModule.emitError(
+              "expected synth.linear_timing_arc in synth.mapping_cost arcs");
+          signalPassFailure();
+          return;
+        }
+
+        if (arc.getPin() != outputName) {
+          hwModule.emitError("mapping cost arc output '")
+              << arc.getPin().getValue() << "' does not match module output '"
+              << outputName.getValue() << "'";
+          signalPassFailure();
+          return;
+        }
+
+        int64_t intrinsicDelay = arc.getIntrinsic();
+
+        // TechMapper currently preserves the old integer per-pin delay model.
+        // The sensitivity, polarity, and input capacitance fields are carried
+        // in the attribute for future load-aware mapping.
+        if (!delayByInput
+                 .try_emplace(arc.getRelatedPin(),
+                              static_cast<DelayType>(intrinsicDelay))
+                 .second) {
+          hwModule.emitError("duplicate mapping cost arc for input '")
+              << arc.getRelatedPin().getValue() << "'";
+          signalPassFailure();
+          return;
+        }
+      }
 
       SmallVector<DelayType> delay;
-      for (auto delayValue : delayAttr) {
-        auto delayArray = cast<ArrayAttr>(delayValue);
-        for (auto delayElement : delayArray) {
-          // FIXME: Currently we assume delay is given as integer attributes,
-          // this should be replaced once we have a proper cell op with
-          // dedicated timing attributes with units.
-          delay.push_back(
-              cast<mlir::IntegerAttr>(delayElement).getValue().getZExtValue());
+      for (const auto &port : hwModule.getPortList()) {
+        if (!port.isInput())
+          continue;
+
+        auto it = delayByInput.find(port.name);
+        if (it == delayByInput.end()) {
+          hwModule.emitError("missing mapping cost arc for input '")
+              << port.name.getValue() << "'";
+          signalPassFailure();
+          return;
         }
+
+        delay.push_back(it->second);
+      }
+
+      if (delay.size() != delayByInput.size()) {
+        hwModule.emitError(
+            "synth.mapping_cost arcs do not match module inputs");
+        signalPassFailure();
+        return;
       }
+
       // Compute NPN Class for the module.
       auto npnClass = getNPNClassFromModule(hwModule);
       if (failed(npnClass)) {