[firtool] Add option to disable layer sink

The layer sink pass is showing some performance problems, and we want the ability to turn it off to work around the issue, until we can properly fix it.
llvm · Dec 13, 2024 · f1582ed · f1582ed
1 parent 2aaf978
commit f1582ed
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Showing 4 changed files with 29 additions and 5 deletions.
diff --git a/include/circt-c/Firtool/Firtool.h b/include/circt-c/Firtool/Firtool.h
@@ -103,6 +103,9 @@ circtFirtoolOptionsSetEnableDebugInfo(CirctFirtoolFirtoolOptions options,
 MLIR_CAPI_EXPORTED void
 circtFirtoolOptionsSetBuildMode(CirctFirtoolFirtoolOptions options,
                                 CirctFirtoolBuildMode value);
+MLIR_CAPI_EXPORTED void
+circtFirtoolOptionsSetDisableLayerSink(CirctFirtoolFirtoolOptions options,
+                                       bool value);
 
 MLIR_CAPI_EXPORTED void
 circtFirtoolOptionsSetDisableOptimization(CirctFirtoolFirtoolOptions options,

diff --git a/include/circt/Firtool/Firtool.h b/include/circt/Firtool/Firtool.h
@@ -96,6 +96,7 @@ class FirtoolOptions {
   }
   bool shouldConvertProbesToSignals() const { return probesToSignals; }
   bool shouldReplaceSequentialMemories() const { return replSeqMem; }
+  bool shouldDisableLayerSink() const { return disableLayerSink; }
   bool shouldDisableOptimization() const { return disableOptimization; }
   bool shouldAdvancedLayerSink() const { return advancedLayerSink; }
   bool shouldLowerMemories() const { return lowerMemories; }
@@ -189,6 +190,11 @@ class FirtoolOptions {
     return *this;
   }
 
+  FirtoolOptions &setDisableLayerSink(bool value) {
+    disableLayerSink = value;
+    return *this;
+  }
+
   FirtoolOptions &setDisableOptimization(bool value) {
     disableOptimization = value;
     return *this;
@@ -381,6 +387,7 @@ class FirtoolOptions {
   firrtl::PreserveValues::PreserveMode preserveMode;
   bool enableDebugInfo;
   BuildMode buildMode;
+  bool disableLayerSink;
   bool disableOptimization;
   bool exportChiselInterface;
   std::string chiselInterfaceOutDirectory;

diff --git a/lib/CAPI/Firtool/Firtool.cpp b/lib/CAPI/Firtool/Firtool.cpp
@@ -125,6 +125,11 @@ void circtFirtoolOptionsSetBuildMode(CirctFirtoolFirtoolOptions options,
   unwrap(options)->setBuildMode(converted);
 }
 
+void circtFirtoolOptionsSetDisableLayerSink(CirctFirtoolFirtoolOptions options,
+                                            bool value) {
+  unwrap(options)->setDisableLayerSink(value);
+}
+
 void circtFirtoolOptionsSetDisableOptimization(
     CirctFirtoolFirtoolOptions options, bool value) {
   unwrap(options)->setDisableOptimization(value);

diff --git a/lib/Firtool/Firtool.cpp b/lib/Firtool/Firtool.cpp
@@ -228,11 +228,14 @@ LogicalResult firtool::populateCHIRRTLToLowFIRRTL(mlir::PassManager &pm,
   //
   // TODO: Improve LowerLayers to avoid the need for canonicalization. See:
   //   https://github.com/llvm/circt/issues/7896
-  if (opt.shouldAdvancedLayerSink())
-    pm.nest<firrtl::CircuitOp>().addPass(firrtl::createAdvancedLayerSinkPass());
-  else
-    pm.nest<firrtl::CircuitOp>().nest<firrtl::FModuleOp>().addPass(
-        firrtl::createLayerSinkPass());
+  if (!opt.shouldDisableLayerSink()) {
+    if (opt.shouldAdvancedLayerSink())
+      pm.nest<firrtl::CircuitOp>().addPass(
+          firrtl::createAdvancedLayerSinkPass());
+    else
+      pm.nest<firrtl::CircuitOp>().nest<firrtl::FModuleOp>().addPass(
+          firrtl::createLayerSinkPass());
+  }
   pm.nest<firrtl::CircuitOp>().addPass(firrtl::createLowerLayersPass());
   if (!opt.shouldDisableOptimization())
     pm.nest<firrtl::CircuitOp>().nest<firrtl::FModuleOp>().addPass(
@@ -522,6 +525,11 @@ struct FirtoolCmdOptions {
                                   "release", "Compile with optimizations")),
       llvm::cl::init(firtool::FirtoolOptions::BuildModeDefault)};
 
+  llvm::cl::opt<bool> disableLayerSink{
+      "disable-layer-sink",
+      llvm::cl::desc("Disable layer sink"),
+  };
+
   llvm::cl::opt<bool> disableOptimization{
       "disable-opt",
       llvm::cl::desc("Disable optimizations"),
@@ -789,6 +797,7 @@ circt::firtool::FirtoolOptions::FirtoolOptions()
   preserveMode = clOptions->preserveMode;
   enableDebugInfo = clOptions->enableDebugInfo;
   buildMode = clOptions->buildMode;
+  disableLayerSink = clOptions->disableLayerSink;
   disableOptimization = clOptions->disableOptimization;
   exportChiselInterface = clOptions->exportChiselInterface;
   chiselInterfaceOutDirectory = clOptions->chiselInterfaceOutDirectory;