Driver: render arguments for the embedded bitcode correctly

[compnerd]

Summary

When embedding bitcode, only a subset of the arguments should be recorded into
the bitcode compilation command line. The frontend job is split into two jobs,
one which will generate the bitcode. Ensure that the arguments for the
compilation to bitcode is properly stripped so that the embedded arguments are
the permitted subset.

[steven_wu]

Thanks for doing this!

Can you add some test cases just to be complete? Other than that, LGTM!

[compnerd]

SVN r342929 (with tests)

include/clang/Basic/DiagnosticDriverKinds.td

 def warn_drv_omp_offload_target_missingbcruntime : Warning<
   "No library '%0' found in the default clang lib directory or in LIBRARY_PATH. Expect degraded performance due to no inlining of runtime functions on target devices.">,
   InGroup<OpenMPTarget>;
+def err_drv_unsupported_embed_bitcode
+    : Error<"%0 is not supported with -fembed-bitcode">;
 def err_drv_bitcode_unsupported_on_toolchain : Error<
   "-fembed-bitcode is not supported on versions of iOS prior to 6.0">;
 

lib/Driver/ToolChains/Clang.cpp

   }
 }
 
-void Clang::AddARMTargetArgs(const llvm::Triple &Triple, const ArgList &Args,
-                             ArgStringList &CmdArgs, bool KernelOrKext) const {
+namespace {
+void RenderARMABI(const llvm::Triple &Triple, const ArgList &Args,
+                  ArgStringList &CmdArgs) {
   // Select the ABI to use.
   // FIXME: Support -meabi.
   // FIXME: Parts of this are duplicated in the backend, unify this somehow.
   const char *ABIName = nullptr;
-  if (Arg *A = Args.getLastArg(options::OPT_mabi_EQ))
+  if (Arg *A = Args.getLastArg(options::OPT_mabi_EQ)) {
     ABIName = A->getValue();
-  else {
+  } else {
     std::string CPU = getCPUName(Args, Triple, /*FromAs*/ false);
     ABIName = llvm::ARM::computeDefaultTargetABI(Triple, CPU).data();
   }
 
   CmdArgs.push_back("-target-abi");
   CmdArgs.push_back(ABIName);
+}
+}
+
+void Clang::AddARMTargetArgs(const llvm::Triple &Triple, const ArgList &Args,
+                             ArgStringList &CmdArgs, bool KernelOrKext) const {
+  RenderARMABI(Triple, Args, CmdArgs);
 
   // Determine floating point ABI from the options & target defaults.
   arm::FloatABI ABI = arm::getARMFloatABI(getToolChain(), Args);

   }
 }
 
+namespace {
+void RenderAArch64ABI(const llvm::Triple &Triple, const ArgList &Args,
+                      ArgStringList &CmdArgs) {
+  const char *ABIName = nullptr;
+  if (Arg *A = Args.getLastArg(options::OPT_mabi_EQ))
+    ABIName = A->getValue();
+  else if (Triple.isOSDarwin())
+    ABIName = "darwinpcs";
+  else
+    ABIName = "aapcs";
+
+  CmdArgs.push_back("-target-abi");
+  CmdArgs.push_back(ABIName);
+}
+}
+
 void Clang::AddAArch64TargetArgs(const ArgList &Args,
                                  ArgStringList &CmdArgs) const {
   const llvm::Triple &Triple = getToolChain().getEffectiveTriple();

                     options::OPT_mno_implicit_float, true))
     CmdArgs.push_back("-no-implicit-float");
 
-  const char *ABIName = nullptr;
-  if (Arg *A = Args.getLastArg(options::OPT_mabi_EQ))
-    ABIName = A->getValue();
-  else if (Triple.isOSDarwin())
-    ABIName = "darwinpcs";
-  else
-    ABIName = "aapcs";
-
-  CmdArgs.push_back("-target-abi");
-  CmdArgs.push_back(ABIName);
+  RenderAArch64ABI(Triple, Args, CmdArgs);
 
   if (Arg *A = Args.getLastArg(options::OPT_mfix_cortex_a53_835769,
                                options::OPT_mno_fix_cortex_a53_835769)) {

     Args.AddLastArg(CmdArgs, options::OPT_save_temps_EQ);
 
   // Embed-bitcode option.
+  // Only white-listed flags below are allowed to be embedded.
   if (C.getDriver().embedBitcodeInObject() && !C.getDriver().isUsingLTO() &&
       (isa<BackendJobAction>(JA) || isa<AssembleJobAction>(JA))) {
     // Add flags implied by -fembed-bitcode.
     Args.AddLastArg(CmdArgs, options::OPT_fembed_bitcode_EQ);
     // Disable all llvm IR level optimizations.
     CmdArgs.push_back("-disable-llvm-passes");
+
+    // reject options that shouldn't be supported in bitcode
+    // also reject kernel/kext
+    static const constexpr unsigned kBitcodeOptionBlacklist[] = {
+        options::OPT_mkernel,
+        options::OPT_fapple_kext,
+        options::OPT_ffunction_sections,
+        options::OPT_fno_function_sections,
+        options::OPT_fdata_sections,
+        options::OPT_fno_data_sections,
+        options::OPT_funique_section_names,
+        options::OPT_fno_unique_section_names,
+        options::OPT_mrestrict_it,
+        options::OPT_mno_restrict_it,
+        options::OPT_mstackrealign,
+        options::OPT_mno_stackrealign,
+        options::OPT_mstack_alignment,
+        options::OPT_mcmodel_EQ,
+        options::OPT_mlong_calls,
+        options::OPT_mno_long_calls,
+        options::OPT_ggnu_pubnames,
+        options::OPT_gdwarf_aranges,
+        options::OPT_fdebug_types_section,
+        options::OPT_fno_debug_types_section,
+        options::OPT_fdwarf_directory_asm,
+        options::OPT_fno_dwarf_directory_asm,
+        options::OPT_mrelax_all,
+        options::OPT_mno_relax_all,
+        options::OPT_ftrap_function_EQ,
+        options::OPT_ffixed_r9,
+        options::OPT_mfix_cortex_a53_835769,
+        options::OPT_mno_fix_cortex_a53_835769,
+        options::OPT_ffixed_x18,
+        options::OPT_mglobal_merge,
+        options::OPT_mno_global_merge,
+        options::OPT_mred_zone,
+        options::OPT_mno_red_zone,
+        options::OPT_Wa_COMMA,
+        options::OPT_Xassembler,
+        options::OPT_mllvm,
+    };
+    for (const auto &A : Args)
+      if (std::find(std::begin(kBitcodeOptionBlacklist),
+                    std::end(kBitcodeOptionBlacklist),
+                    A->getOption().getID()) !=
+          std::end(kBitcodeOptionBlacklist))
+        D.Diag(diag::err_drv_unsupported_embed_bitcode) << A->getSpelling();
+
+    // Render the CodeGen options that need to be passed.
+    if (!Args.hasFlag(options::OPT_foptimize_sibling_calls,
+                      options::OPT_fno_optimize_sibling_calls))
+      CmdArgs.push_back("-mdisable-tail-calls");
+
+    RenderFloatingPointOptions(TC, D, isOptimizationLevelFast(Args), Args,
+                               CmdArgs);
+
+    // Render ABI arguments
+    switch (TC.getArch()) {
+    default: break;
+    case llvm::Triple::arm:
+    case llvm::Triple::armeb:
+    case llvm::Triple::thumbeb:
+      RenderARMABI(Triple, Args, CmdArgs);
+      break;
+    case llvm::Triple::aarch64:
+    case llvm::Triple::aarch64_be:
+      RenderAArch64ABI(Triple, Args, CmdArgs);
+      break;
+    }
+
+    // Optimization level for CodeGen.
+    if (const Arg *A = Args.getLastArg(options::OPT_O_Group)) {
+      if (A->getOption().matches(options::OPT_O4)) {
+        CmdArgs.push_back("-O3");
+        D.Diag(diag::warn_O4_is_O3);
+      } else {
+        A->render(Args, CmdArgs);
+      }
+    }
+
+    // Input/Output file.
+    if (Output.getType() == types::TY_Dependencies) {
+      // Handled with other dependency code.
+    } else if (Output.isFilename()) {
+      CmdArgs.push_back("-o");
+      CmdArgs.push_back(Output.getFilename());
+    } else {
+      assert(Output.isNothing() && "Input output.");
+    }
+
+    for (const auto &II : Inputs) {
+      addDashXForInput(Args, II, CmdArgs);
+      if (II.isFilename())
+        CmdArgs.push_back(II.getFilename());
+      else
+        II.getInputArg().renderAsInput(Args, CmdArgs);
+    }
+
+    C.addCommand(llvm::make_unique<Command>(JA, *this, D.getClangProgramPath(),
+                                            CmdArgs, Inputs));
+    return;
   }
+
   if (C.getDriver().embedBitcodeMarkerOnly() && !C.getDriver().isUsingLTO())
     CmdArgs.push_back("-fembed-bitcode=marker");