[driver] Pass LLVM target_features to flang

Port commit 64bf2a6 to LLVM 16 and resolve merge conflicts. The original
commit message follows:

Pass LLVM target features (-mattr strings) to flang to embed in generated
.ll files. For normal compilation this won't make much difference as the
attributes are passed to clang after flang2 and can be applied there but this
is crucial to enable LTO with flang as clang will not apply the attributes
when building the flang2 output. libLTO will need to read these out of the
object files to apply them.

Signed-off-by: Richard Barton <[email protected]>

Author: RichBarton-Arm

clang/lib/Driver/ToolChains/ClassicFlang.cpp

@@ -60,6 +60,8 @@ class ClassicFlangMacroBuilder : public MacroBuilder {
 void ClassicFlang::ConstructJob(Compilation &C, const JobAction &JA,
                          const InputInfo &Output, const InputInfoList &Inputs,
                          const ArgList &Args, const char *LinkingOutput) const {
+  const Driver &D = getToolChain().getDriver();
+  const llvm::Triple &Triple = getToolChain().getEffectiveTriple();
   ArgStringList CommonCmdArgs;
   ArgStringList UpperCmdArgs;
   ArgStringList LowerCmdArgs;
@@ -374,13 +376,13 @@ void ClassicFlang::ConstructJob(Compilation &C, const JobAction &JA,
 
   // -Mipa has no effect
   if (Arg *A = Args.getLastArg(options::OPT_Mipa)) {
-    getToolChain().getDriver().Diag(diag::warn_drv_clang_unsupported)
+    D.Diag(diag::warn_drv_clang_unsupported)
       << A->getAsString(Args);
   }
 
   // -Minline has no effect
   if (Arg *A = Args.getLastArg(options::OPT_Minline_on)) {
-    getToolChain().getDriver().Diag(diag::warn_drv_clang_unsupported)
+    D.Diag(diag::warn_drv_clang_unsupported)
       << A->getAsString(Args);
   }
 
@@ -654,14 +656,14 @@ void ClassicFlang::ConstructJob(Compilation &C, const JobAction &JA,
   // Use clang's predefined macros
   DiagnosticsEngine DE(new DiagnosticIDs(), new DiagnosticOptions, new IgnoringDiagConsumer());
   std::shared_ptr<clang::TargetOptions> TO = std::make_shared<clang::TargetOptions>();
-  TO->Triple = getToolChain().getEffectiveTriple().getTriple();
+  TO->Triple = Triple.getTriple();
   std::shared_ptr<TargetInfo> TI(clang::TargetInfo::CreateTargetInfo(DE, TO));
   std::string PredefineBuffer;
   llvm::raw_string_ostream Predefines(PredefineBuffer);
   ClassicFlangMacroBuilder Builder(UpperCmdArgs, Args, Predefines);
 
   LangOptions LO;
-  VersionTuple VT = getToolChain().computeMSVCVersion(&getToolChain().getDriver(), Args);
+  VersionTuple VT = getToolChain().computeMSVCVersion(&D, Args);
   if (!VT.empty()) {
     // Set the MSCompatibility version. Subminor version has 5 decimal digits.
     // Minor and major versions have 2 decimal digits each.
@@ -694,7 +696,7 @@ void ClassicFlang::ConstructJob(Compilation &C, const JobAction &JA,
   DefineTypeSize("__LONG_MAX__", TargetInfo::SignedLong, *TI, Builder);
 
   // Add additional predefined macros
-  switch (getToolChain().getEffectiveTriple().getArch()) {
+  switch (Triple.getArch()) {
   case llvm::Triple::aarch64:
     UpperCmdArgs.push_back("-def"); UpperCmdArgs.push_back("__ARM_ARCH__=8");
     break;
@@ -788,7 +790,7 @@ void ClassicFlang::ConstructJob(Compilation &C, const JobAction &JA,
       Arg->claim();
       UpperCmdArgs.push_back("-extend");
     } else {
-      getToolChain().getDriver().Diag(diag::err_drv_unsupported_fixed_line_length)
+      D.Diag(diag::err_drv_unsupported_fixed_line_length)
         << Arg->getAsString(Args);
     }
   }
@@ -832,7 +834,7 @@ void ClassicFlang::ConstructJob(Compilation &C, const JobAction &JA,
     } else if (Value == "95") { // Enable Fortran 2003 semantics
       UpperCmdArgs.push_back("-y"); // Unset XBIT
     } else {
-      getToolChain().getDriver().Diag(diag::err_drv_invalid_allocatable_mode)
+      D.Diag(diag::err_drv_invalid_allocatable_mode)
         << A->getAsString(Args);
     }
   } else { // No argument passed
@@ -982,6 +984,22 @@ void ClassicFlang::ConstructJob(Compilation &C, const JobAction &JA,
   // Remove "noinline" attriblute
   LowerCmdArgs.push_back("-x"); LowerCmdArgs.push_back("183"); LowerCmdArgs.push_back("0x10");
 
+  // Add target features
+  std::vector<StringRef> Features;
+  std::string FeatureList = "";
+  getTargetFeatureList(D, Triple, Args, UpperCmdArgs, false, Features);
+  if (!Features.empty()) {
+    for (unsigned I = 0, N = Features.size(); I < N; ++I) {
+      StringRef Name = Features[I];
+      FeatureList += Name.str();
+      if (I < (N - 1))
+        FeatureList += ',';
+    }
+
+    LowerCmdArgs.push_back("-target_features");
+    LowerCmdArgs.push_back(Args.MakeArgString(FeatureList));
+  }
+
   // Set a -x flag for second part of Fortran frontend
   for (Arg *A : Args.filtered(options::OPT_Mx_EQ)) {
     A->claim();

clang/lib/Driver/ToolChains/CommonArgs.cpp

@@ -765,10 +765,18 @@ static void getWebAssemblyTargetFeatures(const Driver &D,
                             options::OPT_m_wasm_Features_Group);
 }
 
+#ifndef ENABLE_CLASSIC_FLANG
 void tools::getTargetFeatures(const Driver &D, const llvm::Triple &Triple,
                               const ArgList &Args, ArgStringList &CmdArgs,
                               bool ForAS, bool IsAux) {
   std::vector<StringRef> Features;
+#else
+void tools::getTargetFeatureList(const Driver &D,
+                                 const llvm::Triple &Triple,
+                                 const ArgList &Args, ArgStringList &CmdArgs,
+                                 bool ForAS,
+                                 std::vector<StringRef> &Features) {
+#endif
   switch (Triple.getArch()) {
   default:
     break;
@@ -843,6 +851,15 @@ void tools::getTargetFeatures(const Driver &D, const llvm::Triple &Triple,
     loongarch::getLoongArchTargetFeatures(D, Triple, Args, Features);
     break;
   }
+#ifdef ENABLE_CLASSIC_FLANG
+}
+
+void tools::getTargetFeatures(const Driver &D, const llvm::Triple &Triple,
+                              const ArgList &Args, ArgStringList &CmdArgs,
+                              bool ForAS, bool IsAux) {
+  std::vector<StringRef> Features;
+  getTargetFeatureList(D, Triple, Args, CmdArgs, ForAS, Features);
+#endif
 
   for (auto Feature : unifyTargetFeatures(Features)) {
     CmdArgs.push_back(IsAux ? "-aux-target-feature" : "-target-feature");

clang/lib/Driver/ToolChains/CommonArgs.h

@@ -174,6 +174,17 @@ void AddTargetFeature(const llvm::opt::ArgList &Args,
 std::string getCPUName(const Driver &D, const llvm::opt::ArgList &Args,
                        const llvm::Triple &T, bool FromAs = false);
 
+#ifdef ENABLE_CLASSIC_FLANG
+// Helper function extracted from upstream getTargetFeatures. Classic Flang
+// uses this helper to render the target feature options for the Fortran
+// frontend.
+void getTargetFeatureList(const Driver &D,
+                          const llvm::Triple &Triple,
+                          const llvm::opt::ArgList &Args,
+                          llvm::opt::ArgStringList &CmdArgs,
+                          bool ForAS, std::vector<StringRef> &Features);
+#endif
+
 void getTargetFeatures(const Driver &D, const llvm::Triple &Triple,
                        const llvm::opt::ArgList &Args,
                        llvm::opt::ArgStringList &CmdArgs, bool ForAS,

clang/test/Driver/emit-flang-attrs.f90

@@ -0,0 +1,11 @@
+// REQUIRES: aarch64-registered-target
+// REQUIRES: classic_flang
+// RUN: %flang -### -target aarch64-linux-gnu -march=armv8-a -c %s 2>&1 | FileCheck --check-prefix=CHECK-ATTRS-NEON %s
+// RUN: %flang -### -target aarch64-linux-gnu -march=armv8-a+sve -c %s 2>&1 | FileCheck --check-prefix=CHECK-ATTRS-SVE %s
+// RUN: %flang -### -target aarch64-linux-gnu -march=armv8-a+nosve -c %s 2>&1 | FileCheck --check-prefix=CHECK-ATTRS-NOSVE %s
+// CHECK-ATTRS-NEON: "{{.*}}flang2"
+// CHECK-ATTRS-NEON-SAME: "-target_features" "+neon,+v8a
+// CHECK-ATTRS-SVE: "{{.*}}flang2"
+// CHECK-ATTRS-SVE-SAME: "-target_features" "+neon,+v8a,+sve
+// CHECK-ATTRS-NOSVE: "{{.*}}flang2"
+// CHECK-ATTRS-NOSVE-SAME: "-target_features" "+neon,+v8a,-sve