Gemmini: integrate dialect and target plugin (matmul lowering) by 101sparsh · Pull Request #12 · ucb-bar/merlin

101sparsh · 2026-03-04T10:55:11Z

Summary
• Wire Gemmini as a Merlin target plugin under compiler/plugins/target/Gemmini.
• Hook Gemmini dialect + passes under compiler/src/merlin/Dialect/Gemmini (IR + LowerLinalgToGemmini + LowerGemmini + LegalizeForLLVMExport + IR dumps).
• Use iree_compiler_register_plugin(merlin_gemmini) and MERLIN_ENABLE_TARGET_GEMMINI cmake flag.
• Keep all IREE/LLVM changes routed through third_party/iree_bar as build.py expects (no direct edits to external forks here).

Copilot

Pull request overview

Integrates the Gemmini MLIR dialect + lowering passes into Merlin as an IREE compiler target plugin, including a lit test that exercises matmul lowering through to emitted RISC-V Gemmini intrinsics.

Changes:

Adds Gemmini dialect IR, lowering passes (Linalg→Gemmini, Gemmini→LLVM intrinsics), and IR dump pass under compiler/src/merlin/Dialect/Gemmini.
Wires up the Gemmini plugin registration/build under compiler/plugins/target/Gemmini and enables it via iree_compiler_plugin.cmake.
Adds a Gemmini matmul lit test.

Reviewed changes

Copilot reviewed 28 out of 33 changed files in this pull request and generated 11 comments.

Show a summary per file

File	Description
iree_compiler_plugin.cmake	Enables external Gemmini plugin + adds include paths and builds plugin subdir.
compiler/src/merlin/Dialect/Gemmini/_generated/merlin/Dialect/Gemmini/IR/GemminiDialect.h.inc	Generated Gemmini dialect declaration.
compiler/src/merlin/Dialect/Gemmini/_generated/merlin/Dialect/Gemmini/IR/GemminiDialect.cpp.inc	Generated Gemmini dialect definition/type ID.
compiler/src/merlin/Dialect/Gemmini/_generated/GemminiConversions.inc	Generated op→LLVM intrinsic conversion glue.
compiler/src/merlin/Dialect/Gemmini/Transforms/LowerLinalgToGemmini.cpp	New pass/patterns lowering selected Linalg ops to Gemmini tile ops.
compiler/src/merlin/Dialect/Gemmini/Transforms/LowerGemminiPass.cpp	New pass lowering Gemmini ops to LLVM intrinsics / C-stub calls; includes Print lowering.
compiler/src/merlin/Dialect/Gemmini/Transforms/LegalizeForLLVMExport.cpp	Legalizes Gemmini ops for LLVM export + rewrites to Gemmini intrinsic ops.
compiler/src/merlin/Dialect/Gemmini/Transforms/GemminiIRDumps.cpp	Adds IR dumping pass for Gemmini-related ops.
compiler/src/merlin/Dialect/Gemmini/Transforms/CMakeLists.txt	Builds Gemmini transforms as an `iree_cc_library`.
compiler/src/merlin/Dialect/Gemmini/RegisterGemmini.h	Declares dialect + pass registration and pass factory helpers.
compiler/src/merlin/Dialect/Gemmini/RegisterGemmini.cpp	Implements dialect/pass registration and pass factories.
compiler/src/merlin/Dialect/Gemmini/IR/GemminiOps.h	Updates Gemmini ops header includes (LLVM dialect).
compiler/src/merlin/Dialect/Gemmini/IR/Gemmini.td	Updates dialect namespace + defines additional intrinsic ops.
compiler/src/merlin/Dialect/Gemmini/IR/CMakeLists.txt	Builds Gemmini dialect IR as an `iree_cc_library`.
compiler/src/merlin/Dialect/Gemmini/CMakeLists.txt	Builds Gemmini registration library as an `iree_cc_library`.
compiler/plugins/target/Gemmini/test/lit.cfg.py	Lit config for Gemmini plugin tests.
compiler/plugins/target/Gemmini/test/gemmini_matmul_lowering.mlir	Lit test for matmul lowering to Gemmini intrinsics.
compiler/plugins/target/Gemmini/test/Output/gemmini_matmul_lowering.mlir.tmp.dir/module_matmul_dispatch_0_embedded_elf_riscv_64_benchmark.mlir	Generated test output artifact (should not be committed).
compiler/plugins/target/Gemmini/test/Output/gemmini_matmul_lowering.mlir.tmp.dir/module_matmul_dispatch_0_embedded_elf_riscv_64.optimized.bc	Generated test output artifact (should not be committed).
compiler/plugins/target/Gemmini/test/Output/gemmini_matmul_lowering.mlir.tmp.dir/module_matmul_dispatch_0_embedded_elf_riscv_64.linked.bc	Generated test output artifact (should not be committed).
compiler/plugins/target/Gemmini/test/Output/gemmini_matmul_lowering.mlir.tmp.dir/module_matmul_dispatch_0_embedded_elf_riscv_64.codegen.ll	Generated test output artifact (should not be committed).
compiler/plugins/target/Gemmini/test/Output/gemmini_matmul_lowering.mlir.tmp.dir/module_matmul_dispatch_0_embedded_elf_riscv_64.codegen.bc	Generated test output artifact (should not be committed).
compiler/plugins/target/Gemmini/test/Output/gemmini_matmul_lowering.mlir.tmp.dir/module_matmul_dispatch_0.mlir	Generated test output artifact (should not be committed).
compiler/plugins/target/Gemmini/test/Output/gemmini_matmul_lowering.mlir.tmp.dir/configured_module_matmul_dispatch_0.mlir	Generated test output artifact (should not be committed).
compiler/plugins/target/Gemmini/test/Output/gemmini_matmul_lowering.mlir.script	Generated test output artifact (should not be committed).
compiler/plugins/target/Gemmini/test/.lit_test_times.txt	Generated test timing artifact (should not be committed).
compiler/plugins/target/Gemmini/PluginRegistration.cpp	Simplifies plugin session to register dialect/passes and uses DefaultActivated policy.
compiler/plugins/target/Gemmini/CMakeLists.txt	Builds dialect/passes/registration and registers plugin; adds lit suite.

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

Copilot · 2026-03-04T11:09:42Z

+set(_GEMMINI_SRC_DIR "${MERLIN_COMPILER_SOURCE_DIR}/src/merlin/Dialect/Gemmini")
+
+# --- Gemmini Dialect IR Library ---
+iree_cc_library(
+  NAME
+    IR
+  SRCS
+    "${_GEMMINI_SRC_DIR}/IR/GemminiDialect.cpp"
+  DEPS
+    MLIRFuncDialect
+    MLIRIR
+    MLIRLLVMDialect
+    MLIRSideEffectInterfaces
+  PUBLIC
 )


These iree_cc_library targets compile sources that include headers from the Merlin source tree and the pre-generated _generated/ directory, but this CMakeLists doesn't add any target-scoped include directories. Right now it relies on the global include_directories(...) from iree_compiler_plugin.cmake, which makes the plugin harder to build/reuse in isolation.

Consider adding the required include paths via target-scoped includes (e.g. an INCLUDES/HDRS mechanism in iree_cc_library or target_include_directories) for ::IR/::Transforms instead of depending on global include state.

Copilot · 2026-03-04T11:09:43Z

+    Value input0 = inputs[0];
+    Value input1 = inputs[1];
+    Value output0 = ouputs[0];
+    MemRefType input0Type = dyn_cast<MemRefType>(input0.getType());


MatmulLowering assumes all operands are memref-typed and immediately dereferences input0Type (input0Type.getShape()). If linalg.matmul is still tensor-based (common pre-bufferization in IREE), dyn_cast<MemRefType> returns null and this will crash the compiler.

Add a type check (and emit notifyMatchFailure) before using the shapes, or explicitly restrict the pass pipeline so it only runs after bufferization/buffer semantics are guaranteed.

Suggested change

MemRefType input0Type = dyn_cast<MemRefType>(input0.getType());

MemRefType input0Type = dyn_cast<MemRefType>(input0.getType());

if (!input0Type) {

return rewriter.notifyMatchFailure(

matMulOp, "MatmulLowering expects memref-typed operands");

}

Copilot · 2026-03-04T11:09:43Z

+# Include paths so that #include "merlin/Dialect/Gemmini/..." resolves
+# from the source tree AND the pre-generated .inc files.
+include_directories(
+  "${MERLIN_COMPILER_SOURCE_DIR}/src"
+  "${MERLIN_COMPILER_SOURCE_DIR}/src/merlin/Dialect/Gemmini/_generated"
+)


include_directories(...) here sets global include paths for the entire IREE build when this plugin is enabled. That can mask missing includes, change header resolution order, and cause subtle ODR/build issues.

Prefer adding these include paths at the target level (e.g. via the iree_cc_library include/INCLUDES mechanism or target_include_directories on the Gemmini targets) so they only apply to the plugin’s libraries.

Copilot · 2026-03-04T11:09:43Z

@@ -0,0 +1 @@
+2.201907e+00 gemmini_matmul_lowering.mlir


.lit_test_times.txt is a generated file produced by lit test runs and is environment-dependent. It generally shouldn't be committed to the repository; consider removing it and adding it to .gitignore to keep diffs clean.

Suggested change

2.201907e+00 gemmini_matmul_lowering.mlir

# Intentionally left empty; lit test timing data is generated and should not be committed.

Copilot · 2026-03-04T11:09:43Z

+  // Override explicitly to allow conditional dialect dependence.
+  void getDependentDialects(DialectRegistry &registry) const override {
+    registry.insert<LLVM::LLVMDialect>();
+    registry.insert<LLVM::LLVMDialect>();


getDependentDialects inserts LLVM::LLVMDialect twice. This is harmless but redundant; consider removing the duplicate line to keep the dependency list clear.

Suggested change

registry.insert<LLVM::LLVMDialect>();

Copilot · 2026-03-04T11:09:44Z

+    auto ouputs = matMulOp.getOutputs();
+    Location loc = matMulOp.getLoc();
+    Value input0 = inputs[0];
+    Value input1 = inputs[1];
+    Value output0 = ouputs[0];


Typo: local variable ouputs is misspelled (should be outputs). This is a new identifier and makes the code harder to scan/search.

Suggested change

auto ouputs = matMulOp.getOutputs();

Location loc = matMulOp.getLoc();

Value input0 = inputs[0];

Value input1 = inputs[1];

Value output0 = ouputs[0];

auto outputs = matMulOp.getOutputs();

Location loc = matMulOp.getLoc();

Value input0 = inputs[0];

Value input1 = inputs[1];

Value output0 = outputs[0];

Copilot · 2026-03-04T11:09:44Z

+def Gemmini_ConifgLd_IntrOp : Gemmini_IntrOpBase<"config_ld">,
+  Arguments<(ins LLVM_Type, LLVM_Type)>;
+
+def Gemmini_ConfigSt_IntrOp : Gemmini_IntrOpBase<"config_st">,
+  Arguments<(ins LLVM_Type, LLVM_Type)>;
+


The intrinsic op name Gemmini_ConifgLd_IntrOp appears to be misspelled (Conifg vs Config). Since this becomes part of the C++ op class name (and is referenced from multiple passes), it's worth fixing now to avoid a permanent API typo.

Copilot · 2026-03-04T11:09:44Z

+# --- Gemmini Plugin ---
+# Disable the in-tree gemmini plugin (from the IREE fork) in favour of
+# the one provided here in Merlin.
+set(IREE_GEMMINI_EXTERNAL_PLUGIN ON CACHE BOOL "" FORCE)

-# --- Target Plugins ---
-# We use the same flags defined in build.py and the runtime plugin.
+# Include paths so that #include "merlin/Dialect/Gemmini/..." resolves
+# from the source tree AND the pre-generated .inc files.
+include_directories(
+  "${MERLIN_COMPILER_SOURCE_DIR}/src"
+  "${MERLIN_COMPILER_SOURCE_DIR}/src/merlin/Dialect/Gemmini/_generated"
+)

-# 1. SpacemiT X60 Support
-if(MERLIN_BUILD_SPACEMITX60)
-  if(NOT MERLIN_ENABLE_CORE)
-    message(FATAL_ERROR "MERLIN_BUILD_SPACEMITX60 requires MERLIN_ENABLE_CORE=ON")
-  endif()
-
-  if(EXISTS "${MERLIN_COMPILER_SOURCE_DIR}/plugins/target/SpacemiT/CMakeLists.txt")
-    add_subdirectory("${MERLIN_COMPILER_SOURCE_DIR}/plugins/target/SpacemiT"
-                     "${MERLIN_COMPILER_BINARY_ROOT}/target/SpacemiT")
-  endif()
-endif()
-
-# 2. Saturn OPU Support
-if(MERLIN_BUILD_SATURN_OPU)
-  if(NOT MERLIN_ENABLE_CORE)
-    message(FATAL_ERROR "MERLIN_BUILD_SATURN_OPU requires MERLIN_ENABLE_CORE=ON")
-  endif()
-
-  if(EXISTS "${MERLIN_COMPILER_SOURCE_DIR}/plugins/target/Saturn/CMakeLists.txt")
-    add_subdirectory("${MERLIN_COMPILER_SOURCE_DIR}/plugins/target/Saturn"
-                     "${MERLIN_COMPILER_BINARY_ROOT}/target/Saturn")
-  endif()
-endif()
-
-# 3. Gemmini Support
-# If Gemmini is still used by specific targets (like FireSim), 
-# you can gate it with MERLIN_BUILD_GEMMINI or a similar flag.
-if(MERLIN_BUILD_GEMMINI)
-  add_subdirectory("${MERLIN_COMPILER_SOURCE_DIR}/plugins/target/Gemmini"
-                   "${MERLIN_COMPILER_BINARY_ROOT}/target/Gemmini")
-endif()
+# Build the Gemmini plugin (dialect + passes + registration) in one package.
+add_subdirectory(
+  "${MERLIN_COMPILER_SOURCE_DIR}/plugins/target/Gemmini"
+  "${MERLIN_COMPILER_BINARY_ROOT}/target/Gemmini"
+)


add_subdirectory for Gemmini is unconditional, so -DMERLIN_ENABLE_TARGET_GEMMINI=ON/OFF (used by tools/build.py) no longer has any effect. If this is intended to be optional, gate the plugin build on the flag (and consider keeping the previous fatal-error checks for required dependencies).

Copilot · 2026-03-04T11:09:45Z

+@iree_hal_executable_library_query_v0_attrs = private constant [1 x %iree_hal_executable_dispatch_attrs_v0_t] [%iree_hal_executable_dispatch_attrs_v0_t { i64 0, i16 0, i8 0, i8 3, i32 1, i32 1, i16 1, i16 0, i64 0, i64 0, i64 0, i64 0, i64 0 }]
+@3 = private constant [35 x i8] c"matmul_dispatch_0_matmul_4x4x4_f32\00", align 1
+@iree_hal_executable_library_query_v0_names = private constant [1 x ptr] [ptr @3]
+@4 = private constant [153 x i8] c"/Users/sparshsingh/work/merlin/compiler/plugins/target/Gemmini/test/Output/gemmini_matmul_lowering.mlir.tmp.dir/configured_module_matmul_dispatch_0.mlir\00", align 1


This file appears to be a generated test artifact (LLVM IR dumped by the lit RUN pipeline) and it embeds an absolute path from the local machine (/Users/...). These test/Output/... and *.tmp.dir/* artifacts should not be committed (they are non-hermetic, noisy in diffs, and can leak local path/user info).

Recommend deleting the committed Output directory contents and ensuring lit writes to a temporary directory only (plus add a .gitignore rule to prevent re-adding them).

Suggested change

@4 = private constant [153 x i8] c"/Users/sparshsingh/work/merlin/compiler/plugins/target/Gemmini/test/Output/gemmini_matmul_lowering.mlir.tmp.dir/configured_module_matmul_dispatch_0.mlir\00", align 1

@4 = private constant [65 x i8] c"configured_module_matmul_dispatch_0.mlir\00", align 1

Copilot · 2026-03-04T11:09:45Z

+    } else if (memElementType == rewriter.getI8Type() ||
+               memElementType == rewriter.getI32Type()) {
+      formatSpecifierCst = getOrCreateGlobalString(
+          loc, rewriter, "frmt_spec", StringRef("%d \0", 4), parentModule);


formatSpecifierCst is only assigned for f32/f64 and i8/i32 element types. For other element types (e.g. i16/i64, which are otherwise supported by the pass options), it remains uninitialized and is still used in the final LLVM::CallOp, which is undefined behavior.

Handle the default case (emit a match failure / pass error) or initialize formatSpecifierCst for all supported element types.

Suggested change

loc, rewriter, "frmt_spec", StringRef("%d \0", 4), parentModule);

loc, rewriter, "frmt_spec", StringRef("%d \0", 4), parentModule);

} else {

return rewriter.notifyMatchFailure(

op, "unsupported memref element type in Gemmini print lowering");

copparihollmann · 2026-03-04T19:42:04Z

I would suggest that we don't include all the generated files (e.g.: *.mlir, *.s, etc)

These files can be generated by the user.

I would still suggest to have a /test/ folder in the corresponding Gemmini dialect folder to test this.

The correct to use this is either with mlir-lit or iree-lit

Example on how to write those test is this -> LINK TO RELEVANT TEST

copparihollmann · 2026-03-04T19:49:19Z

Also lets not include h.inc files.

Think it from an user perspective :)

What can they generate themselves automatically. Everything that we expose for them to generate we shouldnt include

- Remove pre-generated .inc files and test Output/ artifacts from git - Use iree_tablegen_library to generate .inc from Gemmini.td at build time - Move lit test to compiler/src/merlin/Dialect/Gemmini/test/ - Add .gitignore for generated artifacts (_generated/, *.inc, Output/) - Simplify lit.cfg.py (iree_lit_test handles tool paths) - Update iree_compiler_plugin.cmake to drop _generated include path - Add -DIREE_GEMMINI_EXTERNAL_PLUGIN=ON to tools/build.py

Gemmini: integrate dialect and target plugin (matmul lowering)

7feb46d

101sparsh marked this pull request as draft March 4, 2026 10:59

101sparsh requested review from Copilot and copparihollmann March 4, 2026 10:59

Copilot started reviewing on behalf of 101sparsh March 4, 2026 11:00 View session

Copilot AI reviewed Mar 4, 2026

View reviewed changes

101sparsh assigned 101sparsh and copparihollmann Mar 4, 2026

Docs: add host pybuild instructions; build: Gemmini plugin flag

02fe759

-    MemRefType input0Type = dyn_cast<MemRefType>(input0.getType());
+    MemRefType input0Type = dyn_cast<MemRefType>(input0.getType());
+    if (!input0Type) {
+      return rewriter.notifyMatchFailure(
+          matMulOp, "MatmulLowering expects memref-typed operands");
+    }

	2.201907e+00 gemmini_matmul_lowering.mlir
	# Intentionally left empty; lit test timing data is generated and should not be committed.

	@4 = private constant [153 x i8] c"/Users/sparshsingh/work/merlin/compiler/plugins/target/Gemmini/test/Output/gemmini_matmul_lowering.mlir.tmp.dir/configured_module_matmul_dispatch_0.mlir\00", align 1
	@4 = private constant [65 x i8] c"configured_module_matmul_dispatch_0.mlir\00", align 1

Conversation

101sparsh commented Mar 4, 2026

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Reviewed changes

Uh oh!

Copilot AI Mar 4, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Mar 4, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Mar 4, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Mar 4, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Mar 4, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Mar 4, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Mar 4, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Mar 4, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Mar 4, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Mar 4, 2026

Choose a reason for hiding this comment

Uh oh!

copparihollmann commented Mar 4, 2026

Uh oh!

copparihollmann commented Mar 4, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants