[clang] [CIR] Set the module name to the input filename (PR #160934)

[Andy Kaylor via cfe-commits]

https://github.com/andykaylor created https://github.com/llvm/llvm-project/pull/160934

This sets the MLIR module name to the main filename (according to the SourceManager), if one is available. The module name gets used when creating global init functions, so we will need it to be set.

>From 34bb7014dabb813e6844fb8974992e7d035003e9 Mon Sep 17 00:00:00 2001
From: Andy Kaylor <akaylor at nvidia.com>
Date: Fri, 26 Sep 2025 12:34:22 -0700
Subject: [PATCH] [CIR] Set the module name to the TU filename

The module name gets used when creating global init functions, so we will
need it to be set.
---
 clang/lib/CIR/CodeGen/CIRGenModule.cpp     | 13 +++++++++++++
 clang/test/CIR/CodeGen/lang-c-cpp.cpp      |  4 ++--
 clang/test/CIR/CodeGen/module-filename.cpp | 11 +++++++++++
 clang/test/CIR/CodeGen/opt-info-attr.cpp   | 12 ++++++------
 4 files changed, 32 insertions(+), 8 deletions(-)
 create mode 100644 clang/test/CIR/CodeGen/module-filename.cpp

diff --git a/clang/lib/CIR/CodeGen/CIRGenModule.cpp b/clang/lib/CIR/CodeGen/CIRGenModule.cpp
index eef23a0ebda7f..c977ff9f06de6 100644
--- a/clang/lib/CIR/CodeGen/CIRGenModule.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenModule.cpp
@@ -119,6 +119,19 @@ CIRGenModule::CIRGenModule(mlir::MLIRContext &mlirContext,
                        cir::OptInfoAttr::get(&mlirContext,
                                              cgo.OptimizationLevel,
                                              cgo.OptimizeSize));
+  // Set the module name to be the name of the main file. TranslationUnitDecl
+  // often contains invalid source locations and isn't a reliable source for the
+  // module location.
+  FileID mainFileId = astContext.getSourceManager().getMainFileID();
+  const FileEntry &mainFile =
+      *astContext.getSourceManager().getFileEntryForID(mainFileId);
+  StringRef path = mainFile.tryGetRealPathName();
+  if (!path.empty()) {
+    theModule.setSymName(path);
+    theModule->setLoc(mlir::FileLineColLoc::get(&mlirContext, path,
+                                                /*line=*/0,
+                                                /*column=*/0));
+  }
 }
 
 CIRGenModule::~CIRGenModule() = default;
diff --git a/clang/test/CIR/CodeGen/lang-c-cpp.cpp b/clang/test/CIR/CodeGen/lang-c-cpp.cpp
index e126932104de2..893178384b472 100644
--- a/clang/test/CIR/CodeGen/lang-c-cpp.cpp
+++ b/clang/test/CIR/CodeGen/lang-c-cpp.cpp
@@ -3,8 +3,8 @@
 // RUN: %clang_cc1 -x c -triple x86_64-unknown-linux-gnu -fclangir -emit-cir %s -o %t.c.cir
 // RUN: FileCheck --check-prefix=CIR-C --input-file=%t.c.cir %s
 
-// CIR-CPP: module attributes {{{.*}}cir.lang = #cir.lang<cxx>{{.*}}}
-// CIR-C: module attributes {{{.*}}cir.lang = #cir.lang<c>{{.*}}}
+// CIR-CPP: module{{.*}} attributes {{{.*}}cir.lang = #cir.lang<cxx>{{.*}}}
+// CIR-C: module{{.*}} attributes {{{.*}}cir.lang = #cir.lang<c>{{.*}}}
 
 int main() {
   return 0;
diff --git a/clang/test/CIR/CodeGen/module-filename.cpp b/clang/test/CIR/CodeGen/module-filename.cpp
new file mode 100644
index 0000000000000..05e2e929e3238
--- /dev/null
+++ b/clang/test/CIR/CodeGen/module-filename.cpp
@@ -0,0 +1,11 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir %s -o %t.cir
+// RUN: FileCheck --check-prefix=CIR --input-file=%t.cir %s
+
+// Normally, we try to avoid checking the filename of a test, but that's the
+// entire point of this test, so we use a wildcard for the path but check the
+// filename.
+// CIR: module @"{{.*}}module-filename.cpp"
+
+int main() {
+  return 0;
+}
diff --git a/clang/test/CIR/CodeGen/opt-info-attr.cpp b/clang/test/CIR/CodeGen/opt-info-attr.cpp
index 444286b8db8a9..97071d7ac2b2b 100644
--- a/clang/test/CIR/CodeGen/opt-info-attr.cpp
+++ b/clang/test/CIR/CodeGen/opt-info-attr.cpp
@@ -13,10 +13,10 @@
 
 void f() {}
 
-// CHECK-O0: module attributes
+// CHECK-O0: module{{.*}} attributes
 // CHECK-O0-NOT: cir.opt_info
-// CHECK-O1: module attributes {{.+}}cir.opt_info = #cir.opt_info<level = 1, size = 0>{{.+}}
-// CHECK-O2: module attributes {{.+}}cir.opt_info = #cir.opt_info<level = 2, size = 0>{{.+}}
-// CHECK-O3: module attributes {{.+}}cir.opt_info = #cir.opt_info<level = 3, size = 0>{{.+}}
-// CHECK-Os: module attributes {{.+}}cir.opt_info = #cir.opt_info<level = 2, size = 1>{{.+}}
-// CHECK-Oz: module attributes {{.+}}cir.opt_info = #cir.opt_info<level = 2, size = 2>{{.+}}
+// CHECK-O1: module{{.*}} attributes {{.+}}cir.opt_info = #cir.opt_info<level = 1, size = 0>{{.+}}
+// CHECK-O2: module{{.*}} attributes {{.+}}cir.opt_info = #cir.opt_info<level = 2, size = 0>{{.+}}
+// CHECK-O3: module{{.*}} attributes {{.+}}cir.opt_info = #cir.opt_info<level = 3, size = 0>{{.+}}
+// CHECK-Os: module{{.*}} attributes {{.+}}cir.opt_info = #cir.opt_info<level = 2, size = 1>{{.+}}
+// CHECK-Oz: module{{.*}} attributes {{.+}}cir.opt_info = #cir.opt_info<level = 2, size = 2>{{.+}}