Define __GCC_HAVE_DWARF2_CFI_ASM if applicable

[MaskRay]

Summary

In -fno-exceptions -fno-asynchronous-unwind-tables -g0 mode,
GCC does not emit .cfi_* directives.

% diff <(gcc -fno-asynchronous-unwind-tables -dM -E a.c) <(gcc -dM -E a.c)
130a131
> #define __GCC_HAVE_DWARF2_CFI_ASM 1

This macro is useful because code can decide whether inline asm should include .cfi_* directives.
.cfi_* directives without .cfi_startproc can cause assembler errors.

[MaskRay]

Check -g and exceptions

[MaskRay]

@jansvoboda11 :)

[jansvoboda11]

Could the logic be implemented in the driver?

LGTM regardless.

[MaskRay]

In D97743#2613629, @jansvoboda11 wrote:

Could the logic be implemented in the driver?

LGTM regardless.

No. Res is a clang::CompilerInvocation object. CompilerInvocation is not in the driver... -D -U and __CET__ are implemented in this file, too.

[thakis]

This seems to break tests everywhere: http://45.33.8.238/linux/41275/step_7.txt

[MaskRay]

In D97743#2614792, @thakis wrote:

This seems to break tests everywhere: http://45.33.8.238/linux/41275/step_7.txt

My bad. Fixed by df67d3526962ae51446b1390e7c40e045e580ec2

[thakis]

Still broken: http://45.33.8.238/linux/41278/step_7.txt

[MaskRay]

In D97743#2614827, @thakis wrote:

Still broken: http://45.33.8.238/linux/41278/step_7.txt

b4948c27d2e40586c0c4fa7cbf20b9c40a9f7584

The green Harbomaster misled me..

[jansvoboda11]

In D97743#2614480, @MaskRay wrote:

In D97743#2613629, @jansvoboda11 wrote:

Could the logic be implemented in the driver?

LGTM regardless.

No. Res is a clang::CompilerInvocation object. CompilerInvocation is not in the driver... -D -U and __CET__ are implemented in this file, too.

Right. I meant if it would be possible to move the logic to the driver and pass -D__GCC_HAVE_DWARF2_CFI_ASM=1 explicitly from the driver to -cc1, keeping CompilerInvocation as simple as possible.

[MaskRay]

Move to driver

[jansvoboda11]

In D97743#2614899, @MaskRay wrote:

Move to driver

Thanks!

[MaskRay]

There are some side effects: because -D is passed as command line options, it has <command line> in its filename, so isWrittenInBuiltinFile will not match it (isWrittenInBuiltinFile can match other built-in macros)...

clang/lib/Frontend/CompilerInvocation.cpp

for (const auto &RF : Opts.RemappedFiles)
     GenerateArg(Args, OPT_remap_file, RF.first + ";" + RF.second, SA);
 
   // Don't handle LexEditorPlaceholders. It is implied by the action that is
   // generated elsewhere.
 }
 
 static bool ParsePreprocessorArgs(PreprocessorOptions &Opts, ArgList &Args,
                                   DiagnosticsEngine &Diags,
-                                  frontend::ActionKind Action,
-                                  const FrontendOptions &FrontendOpts) {
+                                  const FrontendOptions &FrontendOpts,
+                                  const llvm::Triple &T) {
   PreprocessorOptions *PreprocessorOpts = &Opts;
   bool Success = true;
 
 #define PREPROCESSOR_OPTION_WITH_MARSHALLING(                                  \
     PREFIX_TYPE, NAME, ID, KIND, GROUP, ALIAS, ALIASARGS, FLAGS, PARAM,        \
     HELPTEXT, METAVAR, VALUES, SPELLING, SHOULD_PARSE, ALWAYS_EMIT, KEYPATH,   \
     DEFAULT_VALUE, IMPLIED_CHECK, IMPLIED_VALUE, NORMALIZER, DENORMALIZER,     \
     MERGER, EXTRACTOR, TABLE_INDEX)                                            \
if (const Arg *A = Args.getLastArg(OPT_fcf_protection_EQ)) {
     if (Name == "branch")
       Opts.addMacroDef("__CET__=1");
     else if (Name == "return")
       Opts.addMacroDef("__CET__=2");
     else if (Name == "full")
       Opts.addMacroDef("__CET__=3");
   }
 
+  if (Args.hasArg(OPT_munwind_tables) &&
+      (T.isOSBinFormatELF() || T.isOSBinFormatMachO()))
+    Opts.addMacroDef("__GCC_HAVE_DWARF2_CFI_ASM=1");
+
   // Add macros from the command line.
   for (const auto *A : Args.filtered(OPT_D, OPT_U)) {
     if (A->getOption().matches(OPT_D))
       Opts.addMacroDef(A->getValue());
     else
       Opts.addMacroUndef(A->getValue());
   }
 
for (const auto *A : Args.filtered(OPT_remap_file)) {
     }
 
     Opts.addRemappedFile(Split.first, Split.second);
   }
 
   // Always avoid lexing editor placeholders when we're just running the
   // preprocessor as we never want to emit the
   // "editor placeholder in source file" error in PP only mode.
-  if (isStrictlyPreprocessorAction(Action))
+  if (isStrictlyPreprocessorAction(FrontendOpts.ProgramAction))
     Opts.LexEditorPlaceholders = false;
 
   return Success;
 }
 
 static void GeneratePreprocessorOutputArgs(
     const PreprocessorOutputOptions &Opts, SmallVectorImpl<const char *> &Args,
     CompilerInvocation::StringAllocator SA, frontend::ActionKind Action) {
bool CompilerInvocation::CreateFromArgsImpl(
   // names.
   Res.getCodeGenOpts().DiscardValueNames &=
       !LangOpts.Sanitize.has(SanitizerKind::Address) &&
       !LangOpts.Sanitize.has(SanitizerKind::KernelAddress) &&
       !LangOpts.Sanitize.has(SanitizerKind::Memory) &&
       !LangOpts.Sanitize.has(SanitizerKind::KernelMemory);
 
   ParsePreprocessorArgs(Res.getPreprocessorOpts(), Args, Diags,
-                        Res.getFrontendOpts().ProgramAction,
-                        Res.getFrontendOpts());
+                        Res.getFrontendOpts(), T);
   ParsePreprocessorOutputArgs(Res.getPreprocessorOutputOpts(), Args, Diags,
                               Res.getFrontendOpts().ProgramAction);
 
   ParseDependencyOutputArgs(Res.getDependencyOutputOpts(), Args, Diags,
                             Res.getFrontendOpts().ProgramAction,
                             Res.getPreprocessorOutputOpts().ShowLineMarkers);
   if (!Res.getDependencyOutputOpts().OutputFile.empty() &&
       Res.getDependencyOutputOpts().Targets.empty()) {

clang/test/Preprocessor/unwind-tables.c

+// RUN: %clang_cc1 %s -verify -munwind-tables -DCFI_ASM -triple x86_64-unknown-elf
+// RUN: %clang_cc1 %s -verify -munwind-tables -DCFI_ASM -triple aarch64-apple-darwin
+// RUN: %clang_cc1 %s -verify -munwind-tables -triple x86_64-windows
+
+// expected-no-diagnostics
+
+#ifdef CFI_ASM
+  #if __GCC_HAVE_DWARF2_CFI_ASM != 1
+  #error "__GCC_HAVE_DWARF2_CFI_ASM not defined"
+  #endif
+#else
+  #ifdef __GCC_HAVE_DWARF2_CFI_ASM
+  #error "__GCC_HAVE_DWARF2_CFI_ASM defined"
+  #endif
+#endif