diff --git a/clang-tools-extra/clang-tidy/llvm/CMakeLists.txt b/clang-tools-extra/clang-tidy/llvm/CMakeLists.txt
--- a/clang-tools-extra/clang-tidy/llvm/CMakeLists.txt
+++ b/clang-tools-extra/clang-tidy/llvm/CMakeLists.txt
@@ -5,6 +5,7 @@
IncludeOrderCheck.cpp
LLVMTidyModule.cpp
PreferIsaOrDynCastInConditionalsCheck.cpp
+ PreferRegisterOverUnsignedCheck.cpp
TwineLocalCheck.cpp
LINK_LIBS
diff --git a/clang-tools-extra/clang-tidy/llvm/LLVMTidyModule.cpp b/clang-tools-extra/clang-tidy/llvm/LLVMTidyModule.cpp
--- a/clang-tools-extra/clang-tidy/llvm/LLVMTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/llvm/LLVMTidyModule.cpp
@@ -13,6 +13,7 @@
#include "HeaderGuardCheck.h"
#include "IncludeOrderCheck.h"
#include "PreferIsaOrDynCastInConditionalsCheck.h"
+#include "PreferRegisterOverUnsignedCheck.h"
#include "TwineLocalCheck.h"
namespace clang {
@@ -24,6 +25,8 @@
void addCheckFactories(ClangTidyCheckFactories &CheckFactories) override {
CheckFactories.registerCheck<LLVMHeaderGuardCheck>("llvm-header-guard");
CheckFactories.registerCheck<IncludeOrderCheck>("llvm-include-order");
+ CheckFactories.registerCheck<PreferRegisterOverUnsignedCheck>(
+ "llvm-prefer-register-over-unsigned");
CheckFactories.registerCheck<readability::NamespaceCommentCheck>(
"llvm-namespace-comment");
CheckFactories.registerCheck<PreferIsaOrDynCastInConditionalsCheck>(
diff --git a/clang-tools-extra/clang-tidy/llvm/PreferRegisterOverUnsignedCheck.h b/clang-tools-extra/clang-tidy/llvm/PreferRegisterOverUnsignedCheck.h
new file mode 100644
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/llvm/PreferRegisterOverUnsignedCheck.h
@@ -0,0 +1,36 @@
+//===--- PreferRegisterOverUnsignedCheck.h - clang-tidy ---------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_LLVM_PREFERREGISTEROVERUNSIGNEDCHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_LLVM_PREFERREGISTEROVERUNSIGNEDCHECK_H
+
+#include "../ClangTidyCheck.h"
+
+namespace clang {
+namespace tidy {
+namespace llvm_check {
+
+/// Historically, LLVM has used `unsigned` to represent registers. Since then
+/// a `Register` object has been introduced for improved type-safety and make
+/// the code more explicit.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/llvm-prefer-register-over-unsigned.html
+class PreferRegisterOverUnsignedCheck : public ClangTidyCheck {
+public:
+ PreferRegisterOverUnsignedCheck(StringRef Name, ClangTidyContext *Context)
+ : ClangTidyCheck(Name, Context) {}
+ void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+ void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+};
+
+} // namespace llvm_check
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_LLVM_PREFERREGISTEROVERUNSIGNEDCHECK_H
diff --git a/clang-tools-extra/clang-tidy/llvm/PreferRegisterOverUnsignedCheck.cpp b/clang-tools-extra/clang-tidy/llvm/PreferRegisterOverUnsignedCheck.cpp
new file mode 100644
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/llvm/PreferRegisterOverUnsignedCheck.cpp
@@ -0,0 +1,62 @@
+//===--- PreferRegisterOverUnsignedCheck.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 "PreferRegisterOverUnsignedCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+namespace llvm_check {
+
+void PreferRegisterOverUnsignedCheck::registerMatchers(MatchFinder *Finder) {
+ auto RegisterClassMatch = hasType(
+ cxxRecordDecl(hasName("llvm::Register")).bind("registerClassDecl"));
+
+ Finder->addMatcher(
+ valueDecl(allOf(
+ hasType(qualType(isUnsignedInteger()).bind("varType")),
+ varDecl(
+ hasInitializer(exprWithCleanups(
+ has(implicitCastExpr(has(cxxMemberCallExpr(allOf(
+ on(RegisterClassMatch),
+ has(memberExpr(hasDeclaration(
+ cxxConversionDecl().bind("operatorDecl"))))))))))))
+ .bind("var"))),
+ this);
+}
+
+void PreferRegisterOverUnsignedCheck::check(const MatchFinder::MatchResult &Result) {
+ const auto *VarType = Result.Nodes.getNodeAs<QualType>("varType");
+ const auto *UserVarDecl = Result.Nodes.getNodeAs<VarDecl>("var");
+
+ diag(UserVarDecl->getLocation(), "var %0 is %1 but holds a register")
+ << UserVarDecl << *VarType;
+ StringRef Replacement = "llvm::Register";
+ const DeclContext *Context = UserVarDecl->getDeclContext();
+ while((Context = Context->getParent()) != nullptr) {
+ if (const auto *Namespace = dyn_cast<NamespaceDecl>(Context))
+ if (Namespace->getQualifiedNameAsString() == "llvm")
+ Replacement = "Register";
+ for (const auto *UsingDirective: Context->using_directives())
+ if (UsingDirective->getNominatedNamespace()
+ ->getQualifiedNameAsString() == "llvm")
+ Replacement = "Register";
+ }
+ diag(UserVarDecl->getLocation(), "use '%0'", DiagnosticIDs::Note)
+ << Replacement
+ << FixItHint::CreateReplacement(
+ UserVarDecl->getTypeSourceInfo()->getTypeLoc().getSourceRange(),
+ Replacement);
+}
+
+} // namespace llvm_check
+} // namespace tidy
+} // namespace clang
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -79,6 +79,12 @@
Finds uses of deprecated Googletest APIs with names containing ``case`` and
replaces them with equivalent APIs with ``suite``.
+- New :doc:`llvm-prefer-register-over-unsigned
+ <clang-tidy/checks/llvm-prefer-register-over-unsigned>` check.
+
+ Finds historical use of ``unsigned`` to hold vregs and physregs and rewrites
+ them to use ``Register``
+
Improvements to include-fixer
-----------------------------
diff --git a/clang-tools-extra/docs/clang-tidy/checks/list.rst b/clang-tools-extra/docs/clang-tidy/checks/list.rst
--- a/clang-tools-extra/docs/clang-tidy/checks/list.rst
+++ b/clang-tools-extra/docs/clang-tidy/checks/list.rst
@@ -274,6 +274,7 @@
llvm-include-order
llvm-namespace-comment
llvm-prefer-isa-or-dyn-cast-in-conditionals
+ llvm-prefer-register-over-unsigned
llvm-twine-local
misc-definitions-in-headers
misc-misplaced-const
diff --git a/clang-tools-extra/docs/clang-tidy/checks/llvm-prefer-register-over-unsigned.rst b/clang-tools-extra/docs/clang-tidy/checks/llvm-prefer-register-over-unsigned.rst
new file mode 100644
--- /dev/null
+++ b/clang-tools-extra/docs/clang-tidy/checks/llvm-prefer-register-over-unsigned.rst
@@ -0,0 +1,27 @@
+.. title:: clang-tidy - llvm-prefer-register-over-unsigned
+
+llvm-prefer-register-over-unsigned
+==================================
+
+Finds historical use of ``unsigned`` to hold vregs and physregs and rewrites
+them to use ``Register``.
+
+Currently this works by finding all variables of unsigned integer type whose
+initialize begins with an implicit cast from ``Register`` to ``unsigned``.
+
+.. code-block:: c++
+
+ void example(MachineOperand &MO) {
+ unsigned Reg = MO.getReg();
+ ...
+ }
+
+becomes:
+
+.. code-block:: c++
+
+ void example(MachineOperand &MO) {
+ Register Reg = MO.getReg();
+ ...
+ }
+
diff --git a/clang-tools-extra/test/clang-tidy/llvm-prefer-register-over-unsigned.cpp b/clang-tools-extra/test/clang-tidy/llvm-prefer-register-over-unsigned.cpp
new file mode 100644
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/llvm-prefer-register-over-unsigned.cpp
@@ -0,0 +1,57 @@
+// RUN: %check_clang_tidy %s llvm-prefer-register-over-unsigned %t
+
+namespace llvm {
+class Register {
+public:
+ operator unsigned();
+};
+} // end namespace llvm
+
+llvm::Register getReg();
+
+void apply_1() {
+ unsigned Reg = getReg();
+ // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: var 'Reg' is 'unsigned int' but holds a register [llvm-prefer-register-over-unsigned]
+ // CHECK-FIXES: apply_1()
+ // CHECK-FIXES-NEXT: llvm::Register Reg = getReg();
+}
+
+void apply_2() {
+ using namespace llvm;
+ unsigned Reg = getReg();
+ // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: var 'Reg' is 'unsigned int' but holds a register [llvm-prefer-register-over-unsigned]
+ // CHECK-FIXES: apply_2()
+ // CHECK-FIXES-NEXT: using namespace llvm;
+ // CHECK-FIXES-NEXT: Register Reg = getReg();
+}
+
+namespace llvm {
+void apply_3() {
+ unsigned Reg = getReg();
+ // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: var 'Reg' is 'unsigned int' but holds a register [llvm-prefer-register-over-unsigned]
+ // CHECK-FIXES: apply_3()
+ // CHECK-FIXES-NEXT: Register Reg = getReg();
+}
+} // end namespace llvm
+
+void done_1() {
+ llvm::Register Reg = getReg();
+ // CHECK-FIXES: done_1()
+ // CHECK-FIXES-NEXT: llvm::Register Reg = getReg();
+}
+
+void done_2() {
+ using namespace llvm;
+ Register Reg = getReg();
+ // CHECK-FIXES: done_2()
+ // CHECK-FIXES-NEXT: using namespace llvm;
+ // CHECK-FIXES-NEXT: Register Reg = getReg();
+}
+
+namespace llvm {
+void done_3() {
+ Register Reg = getReg();
+ // CHECK-FIXES: done_3()
+ // CHECK-FIXES-NEXT: Register Reg = getReg();
+}
+} // end namespace llvm