[flang][mlir] Add llvm.ident metadata when compiling with flang

This brings the behavior of flang in line with clang which also adds
this metadata unconditionally.

Co-authored-by: Tarun Prabhu <[email protected]>

Author: tarunprabhu

flang/include/flang/Optimizer/Dialect/Support/FIRContext.h

@@ -71,6 +71,12 @@ void setTargetFeatures(mlir::ModuleOp mod, llvm::StringRef features);
 /// Get the target features from the Module.
 mlir::LLVM::TargetFeaturesAttr getTargetFeatures(mlir::ModuleOp mod);
 
+/// Set the compiler identifier for the module.
+void setIdent(mlir::ModuleOp mod, llvm::StringRef ident);
+
+/// Get the compiler identifier from the Module.
+llvm::StringRef getIdent(mlir::ModuleOp mod);
+
 /// Helper for determining the target from the host, etc. Tools may use this
 /// function to provide a consistent interpretation of the `--target=<string>`
 /// command-line option.

flang/lib/Lower/Bridge.cpp

@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "flang/Lower/Bridge.h"
+#include "flang/Common/Version.h"
 #include "flang/Lower/Allocatable.h"
 #include "flang/Lower/CallInterface.h"
 #include "flang/Lower/Coarray.h"
@@ -6125,6 +6126,7 @@ Fortran::lower::LoweringBridge::LoweringBridge(
   fir::setTargetFeatures(*module.get(), targetMachine.getTargetFeatureString());
   fir::support::setMLIRDataLayout(*module.get(),
                                   targetMachine.createDataLayout());
+  fir::setIdent(*module.get(), Fortran::common::getFlangFullVersion());
 }
 
 void Fortran::lower::genCleanUpInRegionIfAny(

flang/lib/Optimizer/Dialect/Support/FIRContext.cpp

@@ -114,6 +114,22 @@ mlir::LLVM::TargetFeaturesAttr fir::getTargetFeatures(mlir::ModuleOp mod) {
   return {};
 }
 
+void fir::setIdent(mlir::ModuleOp mod, llvm::StringRef ident) {
+  if (ident.empty())
+    return;
+
+  mlir::MLIRContext *ctx = mod.getContext();
+  mod->setAttr(mlir::LLVM::LLVMDialect::getIdentAttrName(),
+               mlir::StringAttr::get(ctx, ident));
+}
+
+llvm::StringRef fir::getIdent(mlir::ModuleOp mod) {
+  if (auto attr = mod->getAttrOfType<mlir::StringAttr>(
+          mlir::LLVM::LLVMDialect::getIdentAttrName()))
+    return attr;
+  return {};
+}
+
 std::string fir::determineTargetTriple(llvm::StringRef triple) {
   // Treat "" or "default" as stand-ins for the default machine.
   if (triple.empty() || triple == "default")

flang/test/Lower/ident.f90

@@ -0,0 +1,5 @@
+! RUN: bbc -emit-fir %s -o - | FileCheck %s
+! RUN: %flang_fc1 -emit-fir %s -o - | FileCheck %s
+
+! CHECK: module attributes {
+! CHECK-SAME: llvm.ident = "flang version {{.+}}"

mlir/include/mlir/Dialect/LLVMIR/LLVMDialect.td

@@ -32,6 +32,7 @@ def LLVM_Dialect : Dialect {
     static StringRef getNoAliasScopesAttrName() { return "noalias_scopes"; }
     static StringRef getAliasScopesAttrName() { return "alias_scopes"; }
     static StringRef getAccessGroupsAttrName() { return "access_groups"; }
+    static StringRef getIdentAttrName() { return "llvm.ident"; }
 
     /// Names of llvm parameter attributes.
     static StringRef getAlignAttrName() { return "llvm.align"; }

mlir/include/mlir/Target/LLVMIR/ModuleImport.h

@@ -196,6 +196,9 @@ class ModuleImport {
   /// LLVM dialect operation.
   LogicalResult convertLinkerOptionsMetadata();
 
+  /// Converts !llvm.ident metadata to the llvm.ident LLVM ModuleOp attribute.
+  LogicalResult convertIdentMetadata();
+
   /// Converts all LLVM metadata nodes that translate to attributes such as
   /// alias analysis or access group metadata, and builds a map from the
   /// metadata nodes to the converted attributes.

mlir/include/mlir/Target/LLVMIR/ModuleTranslation.h

@@ -329,6 +329,9 @@ class ModuleTranslation {
   /// metadata nodes for them.
   LogicalResult createTBAAMetadata();
 
+  /// Process the ident LLVM Metadata, if it exists.
+  LogicalResult createIdentMetadata();
+
   /// Translates dialect attributes attached to the given operation.
   LogicalResult
   convertDialectAttributes(Operation *op,

mlir/lib/Target/LLVMIR/ModuleImport.cpp

@@ -518,6 +518,23 @@ LogicalResult ModuleImport::convertLinkerOptionsMetadata() {
   return success();
 }
 
+LogicalResult ModuleImport::convertIdentMetadata() {
+  for (const llvm::NamedMDNode &named : llvmModule->named_metadata()) {
+    // llvm.ident should have a single operand. That operand is itself an
+    // MDNode with a single string operand.
+    if (named.getName() != LLVMDialect::getIdentAttrName())
+      continue;
+
+    if (named.getNumOperands() == 1)
+      if (auto *md = dyn_cast<llvm::MDNode>(named.getOperand(0)))
+        if (md->getNumOperands() == 1)
+          if (auto *mdStr = dyn_cast<llvm::MDString>(md->getOperand(0)))
+            mlirModule->setAttr(LLVMDialect::getIdentAttrName(),
+                                builder.getStringAttr(mdStr->getString()));
+  }
+  return success();
+}
+
 LogicalResult ModuleImport::convertMetadata() {
   OpBuilder::InsertionGuard guard(builder);
   builder.setInsertionPointToEnd(mlirModule.getBody());
@@ -546,6 +563,8 @@ LogicalResult ModuleImport::convertMetadata() {
   }
   if (failed(convertLinkerOptionsMetadata()))
     return failure();
+  if (failed(convertIdentMetadata()))
+    return failure();
   return success();
 }
 

mlir/lib/Target/LLVMIR/ModuleTranslation.cpp

@@ -1814,6 +1814,20 @@ LogicalResult ModuleTranslation::createTBAAMetadata() {
   return success();
 }
 
+LogicalResult ModuleTranslation::createIdentMetadata() {
+  if (auto attr = mlirModule->getAttrOfType<StringAttr>(
+          LLVMDialect::getIdentAttrName())) {
+    StringRef ident = attr;
+    llvm::LLVMContext &ctx = llvmModule->getContext();
+    llvm::NamedMDNode *namedMd =
+        llvmModule->getOrInsertNamedMetadata(LLVMDialect::getIdentAttrName());
+    llvm::MDNode *md = llvm::MDNode::get(ctx, llvm::MDString::get(ctx, ident));
+    namedMd->addOperand(md);
+  }
+
+  return success();
+}
+
 void ModuleTranslation::setLoopMetadata(Operation *op,
                                         llvm::Instruction *inst) {
   LoopAnnotationAttr attr =
@@ -1965,6 +1979,8 @@ mlir::translateModuleToLLVMIR(Operation *module, llvm::LLVMContext &llvmContext,
     return nullptr;
   if (failed(translator.createTBAAMetadata()))
     return nullptr;
+  if (failed(translator.createIdentMetadata()))
+    return nullptr;
 
   // Convert other top-level operations if possible.
   for (Operation &o : getModuleBody(module).getOperations()) {

mlir/test/Target/LLVMIR/Import/ident.ll

@@ -0,0 +1,6 @@
+; RUN: mlir-translate -import-llvm -split-input-file %s | FileCheck %s
+
+; CHECK: module attributes {
+; CHECK-SAME: llvm.ident = "flang version 61.7.4"
+!llvm.ident = !{!0}
+!0 = !{!"flang version 61.7.4"}

mlir/test/Target/LLVMIR/ident.mlir

@@ -0,0 +1,6 @@
+// RUN: mlir-translate -mlir-to-llvmir %s | FileCheck %s
+
+// CHECK: !llvm.ident = !{![[ID:[0-9]+]]}
+// CHECK: ![[ID]] = !{!"flang version 61.7.4"}
+module attributes {llvm.ident = "flang version 61.7.4"} {
+}