[clang] c11ff4b - Define __GCC_HAVE_DWARF2_CFI_ASM if applicable

[Fangrui Song via cfe-commits]

Author: Fangrui Song
Date: 2021-03-09T10:52:26-08:00
New Revision: c11ff4bbada3b5127a1f010e0a97a1e6e46fb61a

URL: https://github.com/llvm/llvm-project/commit/c11ff4bbada3b5127a1f010e0a97a1e6e46fb61a
DIFF: https://github.com/llvm/llvm-project/commit/c11ff4bbada3b5127a1f010e0a97a1e6e46fb61a.diff

LOG: Define __GCC_HAVE_DWARF2_CFI_ASM if applicable

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
(integrated assembler: `this directive must appear between .cfi_startproc and .cfi_endproc directives`).

Differential Revision: https://reviews.llvm.org/D97743

Added: 
    clang/test/Preprocessor/unwind-tables.c

Modified: 
    clang/lib/Frontend/CompilerInvocation.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 2606e9f1b185..bd0240870706 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -4355,6 +4355,11 @@ bool CompilerInvocation::CreateFromArgsImpl(
   Res.getCodeGenOpts().Argv0 = Argv0;
   Res.getCodeGenOpts().CommandLineArgs = CommandLineArgs;
 
+  if ((T.isOSBinFormatELF() || T.isOSBinFormatMachO()) &&
+      (Res.getLangOpts()->Exceptions || Res.getCodeGenOpts().UnwindTables ||
+       Res.getCodeGenOpts().getDebugInfo() != codegenoptions::NoDebugInfo))
+    Res.getPreprocessorOpts().addMacroDef("__GCC_HAVE_DWARF2_CFI_ASM=1");
+
   Success &= FixupInvocation(Res, Diags, Args, DashX);
 
   return Success;

diff  --git a/clang/test/Preprocessor/unwind-tables.c b/clang/test/Preprocessor/unwind-tables.c
new file mode 100644
index 000000000000..2f769761b6c6
--- /dev/null
+++ b/clang/test/Preprocessor/unwind-tables.c
@@ -0,0 +1,19 @@
+// RUN: %clang_cc1 %s -verify -munwind-tables -triple x86_64-windows
+// RUN: %clang_cc1 %s -verify -triple x86_64-unknown-elf
+
+// 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 -debug-info-kind=line-tables-only -DCFI_ASM -triple x86_64-unknown-elf
+// RUN: %clang_cc1 %s -verify -fexceptions -DCFI_ASM -triple x86_64-unknown-elf
+
+// 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