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[clang-tidy] Add MLIR check for old op builder usage. #149148

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Moving towards new create method invocation, add check to flag old usage.

@jpienaar jpienaar force-pushed the clangtidy-mlir branch 8 times, most recently from b24a881 to f5d8059 Compare July 16, 2025 18:57
@jpienaar jpienaar marked this pull request as ready for review July 16, 2025 19:14
@jpienaar jpienaar requested review from kadircet and PiotrZSL July 16, 2025 19:15
@llvmbot
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llvmbot commented Jul 16, 2025

@llvm/pr-subscribers-clang-tidy

@llvm/pr-subscribers-clang-tools-extra

Author: Jacques Pienaar (jpienaar)

Changes

Moving towards new create method invocation, add check to flag old usage.


Full diff: https://github.com/llvm/llvm-project/pull/149148.diff

10 Files Affected:

  • (modified) clang-tools-extra/clang-tidy/CMakeLists.txt (+2)
  • (modified) clang-tools-extra/clang-tidy/ClangTidyForceLinker.h (+5)
  • (added) clang-tools-extra/clang-tidy/mlir/CMakeLists.txt (+28)
  • (added) clang-tools-extra/clang-tidy/mlir/MLIRTidyModule.cpp (+39)
  • (added) clang-tools-extra/clang-tidy/mlir/OpBuilderCheck.cpp (+102)
  • (added) clang-tools-extra/clang-tidy/mlir/OpBuilderCheck.h (+21)
  • (modified) clang-tools-extra/docs/ReleaseNotes.rst (+5)
  • (modified) clang-tools-extra/docs/clang-tidy/checks/list.rst (+2)
  • (added) clang-tools-extra/docs/clang-tidy/checks/mlir/op-builder.rst (+22)
  • (added) clang-tools-extra/test/clang-tidy/checkers/mlir/op_builder.cpp (+51)
diff --git a/clang-tools-extra/clang-tidy/CMakeLists.txt b/clang-tools-extra/clang-tidy/CMakeLists.txt
index 93117cf1d6373..b89003bf6c926 100644
--- a/clang-tools-extra/clang-tidy/CMakeLists.txt
+++ b/clang-tools-extra/clang-tidy/CMakeLists.txt
@@ -66,6 +66,7 @@ add_subdirectory(linuxkernel)
 add_subdirectory(llvm)
 add_subdirectory(llvmlibc)
 add_subdirectory(misc)
+add_subdirectory(mlir)
 add_subdirectory(modernize)
 if(CLANG_TIDY_ENABLE_STATIC_ANALYZER)
   add_subdirectory(mpi)
@@ -93,6 +94,7 @@ set(ALL_CLANG_TIDY_CHECKS
   clangTidyLLVMModule
   clangTidyLLVMLibcModule
   clangTidyMiscModule
+  clangTidyMLIRModule
   clangTidyModernizeModule
   clangTidyObjCModule
   clangTidyOpenMPModule
diff --git a/clang-tools-extra/clang-tidy/ClangTidyForceLinker.h b/clang-tools-extra/clang-tidy/ClangTidyForceLinker.h
index adde9136ff1dd..3cde93124c6e4 100644
--- a/clang-tools-extra/clang-tidy/ClangTidyForceLinker.h
+++ b/clang-tools-extra/clang-tidy/ClangTidyForceLinker.h
@@ -94,6 +94,11 @@ extern volatile int MiscModuleAnchorSource;
 static int LLVM_ATTRIBUTE_UNUSED MiscModuleAnchorDestination =
     MiscModuleAnchorSource;
 
+// This anchor is used to force the linker to link the MLIRModule.
+extern volatile int MLIRModuleAnchorSource;
+static int LLVM_ATTRIBUTE_UNUSED MLIRModuleAnchorDestination =
+    MLIRModuleAnchorSource;
+
 // This anchor is used to force the linker to link the ModernizeModule.
 extern volatile int ModernizeModuleAnchorSource;
 static int LLVM_ATTRIBUTE_UNUSED ModernizeModuleAnchorDestination =
diff --git a/clang-tools-extra/clang-tidy/mlir/CMakeLists.txt b/clang-tools-extra/clang-tidy/mlir/CMakeLists.txt
new file mode 100644
index 0000000000000..7d0b2de1df24c
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/mlir/CMakeLists.txt
@@ -0,0 +1,28 @@
+set(LLVM_LINK_COMPONENTS
+  FrontendOpenMP
+  Support
+  )
+
+add_clang_library(clangTidyMLIRModule STATIC
+  MLIRTidyModule.cpp
+  OpBuilderCheck.cpp
+
+  LINK_LIBS
+  clangTidy
+  clangTidyReadabilityModule
+  clangTidyUtils
+  clangTransformer
+
+  DEPENDS
+  omp_gen
+  ClangDriverOptions
+  )
+
+clang_target_link_libraries(clangTidyMLIRModule
+  PRIVATE
+  clangAST
+  clangASTMatchers
+  clangBasic
+  clangLex
+  clangTooling
+  )
diff --git a/clang-tools-extra/clang-tidy/mlir/MLIRTidyModule.cpp b/clang-tools-extra/clang-tidy/mlir/MLIRTidyModule.cpp
new file mode 100644
index 0000000000000..f542020a0afdd
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/mlir/MLIRTidyModule.cpp
@@ -0,0 +1,39 @@
+//===--- MLIRTidyModule.cpp - clang-tidy ----------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "../ClangTidy.h"
+#include "../ClangTidyModule.h"
+#include "../ClangTidyModuleRegistry.h"
+#include "OpBuilderCheck.h"
+
+namespace clang::tidy {
+namespace mlir_check {
+
+class MLIRModule : public ClangTidyModule {
+public:
+  void addCheckFactories(ClangTidyCheckFactories &CheckFactories) override {
+    CheckFactories.registerCheck<OpBuilderCheck>("mlir-op-builder");
+  }
+
+  ClangTidyOptions getModuleOptions() override {
+    ClangTidyOptions Options;
+    return Options;
+  }
+};
+
+// Register the ModuleModule using this statically initialized variable.
+static ClangTidyModuleRegistry::Add<MLIRModule> X("mlir-module",
+                                                  "Adds MLIR lint checks.");
+
+} // namespace mlir_check
+
+// This anchor is used to force the linker to link in the generated object file
+// and thus register the MLIRModule.
+volatile int MLIRModuleAnchorSource = 0; // NOLINT(misc-use-internal-linkage)
+
+} // namespace clang::tidy
diff --git a/clang-tools-extra/clang-tidy/mlir/OpBuilderCheck.cpp b/clang-tools-extra/clang-tidy/mlir/OpBuilderCheck.cpp
new file mode 100644
index 0000000000000..7521096d5b91d
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/mlir/OpBuilderCheck.cpp
@@ -0,0 +1,102 @@
+//===--- OpBuilderCheck.cpp - clang-tidy ----------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "OpBuilderCheck.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
+#include "clang/Basic/LLVM.h"
+#include "clang/Lex/Lexer.h"
+#include "clang/Tooling/Transformer/RangeSelector.h"
+#include "clang/Tooling/Transformer/RewriteRule.h"
+#include "clang/Tooling/Transformer/SourceCode.h"
+#include "clang/Tooling/Transformer/Stencil.h"
+#include "llvm/Support/Error.h"
+
+namespace clang::tidy::mlir_check {
+namespace {
+
+using namespace ::clang::ast_matchers; // NOLINT: Too many names.
+using namespace ::clang::transformer;  // NOLINT: Too many names.
+
+class TypeAsWrittenStencil : public StencilInterface {
+public:
+  explicit TypeAsWrittenStencil(std::string S) : id(std::move(S)) {}
+  std::string toString() const override {
+    return (llvm::Twine("TypeAsWritten(\"") + id + "\")").str();
+  }
+
+  llvm::Error eval(const MatchFinder::MatchResult &match,
+                   std::string *result) const override {
+    auto n = node(id)(match);
+    if (!n)
+      return n.takeError();
+    auto srcRange = n->getAsRange();
+    if (srcRange.isInvalid()) {
+      return llvm::make_error<llvm::StringError>(llvm::errc::invalid_argument,
+                                                 "srcRange is invalid");
+    }
+    auto range = n->getTokenRange(srcRange);
+    auto nextToken = [&](std::optional<Token> token) {
+      if (!token)
+        return token;
+      return clang::Lexer::findNextToken(token->getLocation(),
+                                         *match.SourceManager,
+                                         match.Context->getLangOpts());
+    };
+    auto lessToken = clang::Lexer::findNextToken(
+        range.getBegin(), *match.SourceManager, match.Context->getLangOpts());
+    while (lessToken && lessToken->getKind() != clang::tok::less) {
+      lessToken = nextToken(lessToken);
+    }
+    if (!lessToken) {
+      return llvm::make_error<llvm::StringError>(llvm::errc::invalid_argument,
+                                                 "missing '<' token");
+    }
+    std::optional<Token> endToken = nextToken(lessToken);
+    for (auto greaterToken = nextToken(endToken);
+         greaterToken && greaterToken->getKind() != clang::tok::greater;
+         greaterToken = nextToken(greaterToken)) {
+      endToken = greaterToken;
+    }
+    if (!endToken) {
+      return llvm::make_error<llvm::StringError>(llvm::errc::invalid_argument,
+                                                 "missing '>' token");
+    }
+    *result += clang::tooling::getText(
+        CharSourceRange::getTokenRange(lessToken->getEndLoc(),
+                                       endToken->getLastLoc()),
+        *match.Context);
+    return llvm::Error::success();
+  }
+  std::string id;
+};
+
+Stencil typeAsWritten(StringRef Id) {
+  // Using this instead of `describe` so that we get the exact same spelling.
+  return std::make_shared<TypeAsWrittenStencil>(std::string(Id));
+}
+
+RewriteRuleWith<std::string> OpBuilderCheckRule() {
+  return makeRule(
+      cxxMemberCallExpr(
+          on(expr(hasType(
+                      cxxRecordDecl(isSameOrDerivedFrom("::mlir::OpBuilder"))))
+                 .bind("builder")),
+          callee(cxxMethodDecl(hasTemplateArgument(0, templateArgument()))),
+          callee(cxxMethodDecl(hasName("create"))))
+          .bind("call"),
+      changeTo(cat(typeAsWritten("call"), "::create(", node("builder"), ", ",
+                   callArgs("call"), ")")),
+      cat("Use OpType::create(builder, ...) instead of "
+          "builder.create<OpType>(...)"));
+}
+} // namespace
+
+OpBuilderCheck::OpBuilderCheck(StringRef Name, ClangTidyContext *Context)
+    : TransformerClangTidyCheck(OpBuilderCheckRule(), Name, Context) {}
+
+} // namespace clang::tidy::mlir_check
diff --git a/clang-tools-extra/clang-tidy/mlir/OpBuilderCheck.h b/clang-tools-extra/clang-tidy/mlir/OpBuilderCheck.h
new file mode 100644
index 0000000000000..792ac7b782add
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/mlir/OpBuilderCheck.h
@@ -0,0 +1,21 @@
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MLIR_OPBUILDERCHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MLIR_OPBUILDERCHECK_H
+
+#include "../utils/TransformerClangTidyCheck.h"
+
+namespace clang::tidy::mlir_check {
+
+/// Checks for uses of `OpBuilder::create<T>` and suggests using `T::create`
+/// instead.
+class OpBuilderCheck : public utils::TransformerClangTidyCheck {
+public:
+  OpBuilderCheck(StringRef Name, ClangTidyContext *Context);
+
+  bool isLanguageVersionSupported(const LangOptions &LangOpts) const override {
+    return getLangOpts().CPlusPlus;
+  }
+};
+
+} // namespace clang::tidy::mlir_check
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MLIR_OPBUILDERCHECK_H
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index 9eb3835fe8340..466b2a9a7e84c 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -162,6 +162,11 @@ New checks
   Finds uses of ``std::lock_guard`` and suggests replacing them with C++17's
   alternative ``std::scoped_lock``.
 
+- New :doc:`mlir-op-builder
+  <clang-tidy/checks/mlir/op-builder>` check.
+
+  Flags usage of old OpBuilder format.
+
 - New :doc:`portability-avoid-pragma-once
   <clang-tidy/checks/portability/avoid-pragma-once>` check.
 
diff --git a/clang-tools-extra/docs/clang-tidy/checks/list.rst b/clang-tools-extra/docs/clang-tidy/checks/list.rst
index 0cffbd323caa2..49cd008e7588c 100644
--- a/clang-tools-extra/docs/clang-tidy/checks/list.rst
+++ b/clang-tools-extra/docs/clang-tidy/checks/list.rst
@@ -24,6 +24,7 @@ Clang-Tidy Checks
    llvm/*
    llvmlibc/*
    misc/*
+   mlir/*
    modernize/*
    mpi/*
    objc/*
@@ -279,6 +280,7 @@ Clang-Tidy Checks
    :doc:`misc-unused-using-decls <misc/unused-using-decls>`, "Yes"
    :doc:`misc-use-anonymous-namespace <misc/use-anonymous-namespace>`,
    :doc:`misc-use-internal-linkage <misc/use-internal-linkage>`, "Yes"
+   :doc:`mlir-op-builder <mlir/op-builder>`, "Yes"
    :doc:`modernize-avoid-bind <modernize/avoid-bind>`, "Yes"
    :doc:`modernize-avoid-c-arrays <modernize/avoid-c-arrays>`,
    :doc:`modernize-concat-nested-namespaces <modernize/concat-nested-namespaces>`, "Yes"
diff --git a/clang-tools-extra/docs/clang-tidy/checks/mlir/op-builder.rst b/clang-tools-extra/docs/clang-tidy/checks/mlir/op-builder.rst
new file mode 100644
index 0000000000000..30bae06a36836
--- /dev/null
+++ b/clang-tools-extra/docs/clang-tidy/checks/mlir/op-builder.rst
@@ -0,0 +1,22 @@
+.. title:: clang-tidy - mlir-op-builder
+
+mlir-op-builder
+===============
+
+Flags usage of old form of invoking create on `OpBuilder` and suggesting new
+form.
+
+Example
+-------
+
+.. code-block:: c++
+
+  builder.create<FooOp>(builder.getUnknownLoc(), "baz");
+
+
+Transforms to:
+
+.. code-block:: c++
+
+  FooOp::create(builder, builder.getUnknownLoc(), "baz");
+
diff --git a/clang-tools-extra/test/clang-tidy/checkers/mlir/op_builder.cpp b/clang-tools-extra/test/clang-tidy/checkers/mlir/op_builder.cpp
new file mode 100644
index 0000000000000..bf60c665e86ad
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/checkers/mlir/op_builder.cpp
@@ -0,0 +1,51 @@
+// RUN: %check_clang_tidy --match-partial-fixes %s mlir-op-builder %t
+
+namespace mlir {
+class Location {};
+class OpBuilder {
+public:
+  template <typename OpTy, typename... Args>
+  OpTy create(Location location, Args &&...args) {
+    return OpTy(args...);
+  }
+  Location getUnknownLoc() { return Location(); }
+};
+class ImplicitLocOpBuilder : public OpBuilder {
+public:
+  template <typename OpTy, typename... Args>
+  OpTy create(Args &&...args) {
+    return OpTy(args...);
+  }
+};
+struct ModuleOp {
+  ModuleOp() {}
+  static ModuleOp create(OpBuilder &builder, Location location) {
+    return ModuleOp();
+  }
+};
+struct NamedOp {
+  NamedOp(const char* name) {}
+  static NamedOp create(OpBuilder &builder, Location location, const char* name) {
+    return NamedOp(name);
+  }
+};
+} // namespace mlir
+
+void f() {
+  mlir::OpBuilder builder;
+  // CHECK-MESSAGES: :[[@LINE+2]]:3: warning: Use OpType::create(builder, ...) instead of builder.create<OpType>(...) [mlir-op-builder]
+  // CHECK-FIXES: mlir::  ModuleOp::create(builder, builder.getUnknownLoc())
+  builder.create<mlir::  ModuleOp>(builder.getUnknownLoc());
+
+  using mlir::NamedOp;
+  // CHECK-MESSAGES: :[[@LINE+2]]:3: warning: Use OpType::create(builder, ...) instead of builder.create<OpType>(...) [mlir-op-builder]
+  // CHECK-FIXES: NamedOp::create(builder, builder.getUnknownLoc(), "baz")
+  builder.create<NamedOp>(builder.getUnknownLoc(), "baz");
+
+  mlir::ImplicitLocOpBuilder ib;
+  // Note: extra space in the case where there is no other arguments. Could be
+  // improved, but also clang-format will do that just post.
+  // CHECK-MESSAGES: :[[@LINE+2]]:3: warning: Use OpType::create(builder, ...) instead of builder.create<OpType>(...) [mlir-op-builder]
+  // CHECK-FIXES: mlir::ModuleOp::create(ib )
+  ib.create<mlir::ModuleOp>();
+}

@vbvictor
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I think we should go through an RFC before creating a new module.

TBH, I don't think we need a new module for MLIR in upstream since it is not a widely known thing in C++ community. Would it be viable for MLIR folks to use plugins or have a dedicated directory with custom checks in MLIR project like libcxx do.

@jpienaar
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I considered placing it in LLVM module instead given part of LLVM project.

@carlosgalvezp
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I agree that a new module seems unnecessary, do we know that it will contain more checks in the future? If not moving to llvm or plugins would perhaps be more suitable.

@jpienaar
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Good question. I think there are a few style things we could flag, but nothing planned. And this current one I'd assume lives for like 6-9 months and then we remove it. Having this flagged on commits to both MLIR & Flang to reduce migration need later. Well I know a couple of downstream projects that would want this too and I'd mass apply this across multiple projects while guarding against new additions before deprecation. I can move to LLVM module and then delete it in like 9 months.

@EugeneZelenko EugeneZelenko requested a review from vbvictor July 17, 2025 01:31
jpienaar and others added 4 commits July 17, 2025 14:28
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I think we need a more verbose check name for users to understand what is the check about, e.g.
llvm-prefer-new-mlir-op-builder
llvm-use-new-mlir-op-builder
llvm-use-static-function-mlir-op-builder

};
} // namespace mlir

void f() {
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Could you add tests with builder.create

  • inside macros
  • inside template functions when template parameter of create is dependent.
  • when builder.create is in multiple lines like:
builder.
   create<NamedOp>(
     builder.getUnknownLoc(),
     "baz");

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For the macro case, the matcher matches, but the rewrite is never attempted. Its been a few years since I last wrote a clang-tidy check, so not sure why. If I change to a noopEdit then it is flagged not sure if due to returning an ASTEdit rather than EditGenerator. Using the latter may be possible, is rather low level but perhaps possible. Is there a pattern I'm missing here?

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