[firtool] Add infra for pass plugins (#6254)

This PR ads MLIR pass plugin functionality to firtool pipeline to dynamically load pass plugins and execute passes. 
`*.so` file is load with`--load-pass-plugin` option. Currently we can insert passes to 4 places in the pipeline: (1) after FIRRTL parsing (2) before LowerToHW (3) after HW lowering (4) after SV lowering.

cmake/modules/CIRCTConfig.cmake.in

@@ -18,7 +18,9 @@ set_property(GLOBAL PROPERTY CIRCT_CONVERSION_LIBS "@CIRCT_CONVERSION_LIBS@")
 set_property(GLOBAL PROPERTY CIRCT_TRANSLATION_LIBS "@CIRCT_TRANSLATION_LIBS@")
 
 # Provide all our library targets to users.
-@CIRCT_CONFIG_INCLUDE_EXPORTS@
+if(NOT TARGET CIRCTSupport)
+  @CIRCT_CONFIG_INCLUDE_EXPORTS@
+endif()
 
 # By creating these targets here, subprojects that depend on CIRCT's
 # tablegen-generated headers can always depend on these targets whether building

tools/firtool/CMakeLists.txt

@@ -4,6 +4,9 @@ set(LLVM_LINK_COMPONENTS
 
 add_circt_tool(firtool
   firtool.cpp
+
+  DEPENDS
+  SUPPORT_PLUGINS
 )
 llvm_update_compile_flags(firtool)
 target_link_libraries(firtool PRIVATE
@@ -27,3 +30,5 @@ target_link_libraries(firtool PRIVATE
   MLIRFuncDialect
   MLIRTransforms
 )
+
+export_executable_symbols_for_plugins(firtool)

tools/firtool/firtool.cpp

@@ -46,9 +46,11 @@
 #include "mlir/Pass/Pass.h"
 #include "mlir/Pass/PassInstrumentation.h"
 #include "mlir/Pass/PassManager.h"
+#include "mlir/Pass/PassRegistry.h"
 #include "mlir/Support/FileUtilities.h"
 #include "mlir/Support/Timing.h"
 #include "mlir/Support/ToolUtilities.h"
+#include "mlir/Tools/Plugins/PassPlugin.h"
 #include "mlir/Transforms/Passes.h"
 #include "llvm/Support/Chrono.h"
 #include "llvm/Support/CommandLine.h"
@@ -129,6 +131,34 @@ static cl::opt<bool>
 
 static firtool::FirtoolOptions firtoolOptions(mainCategory);
 
+static cl::list<std::string>
+    passPlugins("load-pass-plugin", cl::desc("Load passes from plugin library"),
+                cl::CommaSeparated, cl::cat(mainCategory));
+
+static cl::opt<std::string>
+    highFIRRTLPassPlugin("high-firrtl-pass-plugin",
+                         cl::desc("Insert passes after parsing FIRRTL. Specify "
+                                  "passes with MLIR textual format."),
+                         cl::init(""), cl::cat(mainCategory));
+
+static cl::opt<std::string>
+    lowFIRRTLPassPlugin("low-firrtl-pass-plugin",
+                        cl::desc("Insert passes before lowering to HW. Specify "
+                                 "passes with MLIR textual format."),
+                        cl::init(""), cl::cat(mainCategory));
+
+static cl::opt<std::string>
+    hwPassPlugin("hw-pass-plugin",
+                 cl::desc("Insert passes after lowering to HW. Specify "
+                          "passes with MLIR textual format."),
+                 cl::init(""), cl::cat(mainCategory));
+
+static cl::opt<std::string>
+    svPassPlugin("sv-pass-plugin",
+                 cl::desc("Insert passes after lowering to SV. Specify "
+                          "passes with MLIR textual format."),
+                 cl::init(""), cl::cat(mainCategory));
+
 enum OutputFormatKind {
   OutputParseOnly,
   OutputIRFir,
@@ -350,17 +380,31 @@ static LogicalResult processBuffer(
     return printOp(*module, (*outputFile)->os());
   }
 
+  if (!highFIRRTLPassPlugin.empty())
+    if (failed(parsePassPipeline(StringRef(highFIRRTLPassPlugin), pm)))
+      return failure();
+
   if (failed(firtool::populateCHIRRTLToLowFIRRTL(pm, firtoolOptions, *module,
                                                  inputFilename)))
     return failure();
 
+  if (!lowFIRRTLPassPlugin.empty())
+    if (failed(parsePassPipeline(StringRef(lowFIRRTLPassPlugin), pm)))
+      return failure();
+
   // Lower if we are going to verilog or if lowering was specifically requested.
   if (outputFormat != OutputIRFir) {
     if (failed(firtool::populateLowFIRRTLToHW(pm, firtoolOptions)))
       return failure();
+    if (!hwPassPlugin.empty())
+      if (failed(parsePassPipeline(StringRef(hwPassPlugin), pm)))
+        return failure();
     if (outputFormat != OutputIRHW)
       if (failed(firtool::populateHWToSV(pm, firtoolOptions)))
         return failure();
+    if (!svPassPlugin.empty())
+      if (failed(parsePassPipeline(StringRef(svPassPlugin), pm)))
+        return failure();
   }
 
   // If the user requested HGLDD debug info emission, enable Verilog location
@@ -612,6 +656,19 @@ int main(int argc, char **argv) {
   // MLIR options are added below.
   cl::HideUnrelatedOptions(mainCategory);
 
+  /// Set the callback to load a pass plugin.
+  passPlugins.setCallback([&](const std::string &pluginPath) {
+    llvm::errs() << "[firtool] load plugin " << pluginPath << '\n';
+    auto plugin = PassPlugin::load(pluginPath);
+    if (!plugin) {
+      errs() << plugin.takeError() << '\n';
+      errs() << "Failed to load passes from '" << pluginPath
+             << "'. Request ignored.\n";
+      return;
+    }
+    plugin.get().registerPassRegistryCallbacks();
+  });
+
   // Register passes before parsing command-line options, so that they are
   // available for use with options like `--mlir-print-ir-before`.
   {