[circt-synth] Populate pipelines until AIG lowering (#7741)

This commit populates circt-synth pipeline from CombToAIG to LowerWordToBits with optimizations.

test/circt-synth/basic.mlir

@@ -1,7 +1,23 @@
 // RUN: circt-synth %s | FileCheck %s
+// RUN: circt-synth %s --until-before aig-lowering | FileCheck %s --check-prefix=AIG
 
+// AIG-LABEL: @and
 // CHECK-LABEL: @and
-hw.module @and(in %a: i1, in %b: i1, out and: i1) {
-  %0 = comb.and %a, %b : i1
-  hw.output %0 : i1
+hw.module @and(in %a: i2, in %b: i2, in %c: i2, out and: i2) {
+  %0 = comb.and %a, %b, %c : i2
+  // AIG-NEXT:  %[[AND_INV:.+]] = aig.and_inv %a, %b, %c : i2
+  // AIG-NEXT: hw.output %[[AND_INV]] : i2
+  // CHECK-DAG: %[[B_1:.+]] = comb.extract %b from 1 : (i2) -> i1
+  // CHECK-DAG: %[[C_1:.+]] = comb.extract %c from 1 : (i2) -> i1
+  // CHECK-DAG: %[[AND_INV_0:.+]] = aig.and_inv %0, %[[C_1]] : i1
+  // CHECK-DAG: %[[B_0:.+]] = comb.extract %b from 0 : (i2) -> i1
+  // CHECK-DAG: %[[C_0:.+]] = comb.extract %c from 0 : (i2) -> i1
+  // CHECK-DAG: %[[AND_INV_1:.+]] = aig.and_inv %[[B_0]], %[[C_0]] : i1
+  // CHECK-DAG: %[[A_1:.+]] = comb.extract %a from 1 : (i2) -> i1
+  // CHECK-DAG: %[[AND_INV_2:.+]] = aig.and_inv %[[A_1]], %[[AND_INV_0]] : i1
+  // CHECK-DAG: %[[A_0:.+]] = comb.extract %a from 0 : (i2) -> i1
+  // CHECK-DAG: %[[AND_INV_3:.+]] = aig.and_inv %[[A_0]], %[[AND_INV_1]] : i1
+  // CHECK-DAG: %[[CONCAT:.+]] = comb.concat %[[AND_INV_2]], %[[AND_INV_3]] : i1, i1
+  // CHECK-NEXT: hw.output %[[CONCAT]] : i2
+  hw.output %0 : i2
 }

tools/circt-synth/CMakeLists.txt

@@ -2,7 +2,9 @@ add_circt_tool(circt-synth circt-synth.cpp)
 target_link_libraries(circt-synth
   PRIVATE
   CIRCTAIG
+  CIRCTAIGTransforms
   CIRCTComb
+  CIRCTCombToAIG
   CIRCTHW
   CIRCTSupport
   MLIRIR

tools/circt-synth/circt-synth.cpp

@@ -11,6 +11,7 @@
 ///
 //===----------------------------------------------------------------------===//
 
+#include "circt/Conversion/CombToAIG.h"
 #include "circt/Dialect/AIG/AIGDialect.h"
 #include "circt/Dialect/AIG/AIGPasses.h"
 #include "circt/Dialect/Comb/CombDialect.h"
@@ -62,11 +63,53 @@ static cl::opt<bool>
                           cl::desc("Log executions of toplevel module passes"),
                           cl::init(false), cl::cat(mainCategory));
 
+// Options to control early-out from pipeline.
+enum Until { UntilAIGLowering, UntilEnd };
+
+static auto runUntilValues = llvm::cl::values(
+    clEnumValN(UntilAIGLowering, "aig-lowering", "Lowering of AIG"),
+    clEnumValN(UntilEnd, "all", "Run entire pipeline (default)"));
+
+static llvm::cl::opt<Until> runUntilBefore(
+    "until-before", llvm::cl::desc("Stop pipeline before a specified point"),
+    runUntilValues, llvm::cl::init(UntilEnd), llvm::cl::cat(mainCategory));
+static llvm::cl::opt<Until> runUntilAfter(
+    "until-after", llvm::cl::desc("Stop pipeline after a specified point"),
+    runUntilValues, llvm::cl::init(UntilEnd), llvm::cl::cat(mainCategory));
+
+//===----------------------------------------------------------------------===//
+// Main Tool Logic
+//===----------------------------------------------------------------------===//
+
+static bool untilReached(Until until) {
+  return until >= runUntilBefore || until > runUntilAfter;
+}
+
 //===----------------------------------------------------------------------===//
 // Tool implementation
 //===----------------------------------------------------------------------===//
 
-static void populateSynthesisPipeline(PassManager &pm) {}
+static void populateSynthesisPipeline(PassManager &pm) {
+  auto &mpm = pm.nest<hw::HWModuleOp>();
+  mpm.addPass(circt::createConvertCombToAIG());
+  mpm.addPass(createCSEPass());
+  if (untilReached(UntilAIGLowering))
+    return;
+  mpm.addPass(createSimpleCanonicalizerPass());
+  mpm.addPass(createCSEPass());
+  mpm.addPass(aig::createLowerVariadic());
+  // TODO: LowerWordToBits is not scalable for large designs. Change to
+  // conditionally enable the pass once the rest of the pipeline was able to
+  // handle multibit operands properly.
+  mpm.addPass(aig::createLowerWordToBits());
+  mpm.addPass(createCSEPass());
+  mpm.addPass(createSimpleCanonicalizerPass());
+  // TODO: Add balancing, rewriting, FRAIG conversion, etc.
+  if (untilReached(UntilEnd))
+    return;
+
+  // TODO: Add LUT mapping, etc.
+}
 
 /// This function initializes the various components of the tool and
 /// orchestrates the work to be done.