[ARM] Improve diagnostics message when Neon is unsupported

Summary:
Whenever Neon is not supported, a generic message is printed:

  error: "NEON support not enabled"

Followed by a series of other error messages that are not useful once
the first one is printed.

This patch gives a more precise message in the case where Neon is
unsupported because an invalid float ABI was specified: the soft float
ABI.

  error: "NEON intrinsics not available with the soft-float ABI. Please
  use -mfloat-abi=softfp or -mfloat-abi=hard"

This message is the same one that GCC gives, so it is also making their
diagnostics more compatible with each other.

Also, by rearranging preprocessor directives, these "unsupported" error
messages are now the only ones printed out, which is also GCC's
behaviour.

Differential Revision: https://reviews.llvm.org/D81847

diff --git a/clang/utils/TableGen/NeonEmitter.cpp b/clang/utils/TableGen/NeonEmitter.cpp
index 813a0c8..d5bf59e 100644 (file)
--- a/clang/utils/TableGen/NeonEmitter.cpp
+++ b/clang/utils/TableGen/NeonEmitter.cpp
@@ -2312,9 +2312,14 @@ void NeonEmitter::run(raw_ostream &OS) {
   OS << "#ifndef __ARM_NEON_H\n";
   OS << "#define __ARM_NEON_H\n\n";
 
+  OS << "#ifndef __ARM_FP\n";
+  OS << "#error \"NEON intrinsics not available with the soft-float ABI. "
+        "Please use -mfloat-abi=softfp or -mfloat-abi=hard\"\n";
+  OS << "#else\n\n";
+
   OS << "#if !defined(__ARM_NEON)\n";
   OS << "#error \"NEON support not enabled\"\n";
-  OS << "#endif\n\n";
+  OS << "#else\n\n";
 
   OS << "#include <stdint.h>\n\n";
 
@@ -2404,6 +2409,8 @@ void NeonEmitter::run(raw_ostream &OS) {
 
   OS << "\n";
   OS << "#undef __ai\n\n";
+  OS << "#endif /* if !defined(__ARM_NEON) */\n";
+  OS << "#endif /* ifndef __ARM_FP */\n";
   OS << "#endif /* __ARM_NEON_H */\n";
 }