[Clang] Improve diagnostic message for loop hint pragma

[eopXD]

Summary

Originally the loop hint is not displayed correctly in the diagnostic.
This patch fixes it.

[eopXD]

Trigger upon parent revision.

[SjoerdMeijer]

clang/lib/Parse/ParsePragma.cpp

1306

We've got some duplication now, as "loop" is also checked in line 1310. Can you see if you can merge these checks, simplify things here a bit?

[eopXD]

Rebase upon latest main and simplify existing checks.

[eopXD]

clang/lib/Parse/ParsePragma.cpp

1306

Yes, the case for loop in below can now be removed. Thank you.

[SjoerdMeijer]

clang/lib/Parse/ParsePragma.cpp

1306

I was hoping that modifying the "loop" case would work:

.Case("loop", (llvm::Twine("clang loop ") + Option.getIdentifierInfo()->getName()).str());

[eopXD]

Update code based on suggestion.

[eopXD]

clang/lib/Parse/ParsePragma.cpp

1306

Your suggestion is better than mine, thank you :)

[Meinersbur]

LGTM

clang/lib/Parse/ParsePragma.cpp

1308

ClangLoopStr is unused now

[eopXD]

Update code to handle when IdentifierInfo is null.
The .Case syntax seems to evaulate expression in other non-trigger cases.
The "loop" case was triggered for test case in loop unroll and jam, resulting
in segmentation fault. Anyway the updated code shall be safe now.

clang/lib/Parse/ParsePragma.cpp

struct PragmaLoopHintInfo {
   Token PragmaName;
   Token Option;
   ArrayRef<Token> Toks;
 };
 } // end anonymous namespace
 
 static std::string PragmaLoopHintString(Token PragmaName, Token Option) {
   StringRef Str = PragmaName.getIdentifierInfo()->getName();
+  if (Str == "loop")
+    return (llvm::Twine("clang loop ") + Option.getIdentifierInfo()->getName()).str();
   std::string ClangLoopStr = (llvm::Twine("clang loop ") + Str).str();
   return std::string(llvm::StringSwitch<StringRef>(Str)
                          .Case("loop", ClangLoopStr)
                          .Case("unroll_and_jam", Str)
                          .Case("unroll", Str)
                          .Default(""));
 }
 
 bool Parser::HandlePragmaLoopHint(LoopHint &Hint) {

clang/test/Parser/pragma-loop.cpp

 
 void foo(void) {
 #pragma clang loop vectorize_predicate(enable)
 /* expected-error {{expected statement}} */ }
 
 void foo(int *List, int Length) {
   int i;
 #pragma clang loop vectorize(enable, extra)
-/* expected-warning {{extra tokens at end of '#pragma clang loop loop' - ignored}}*/ while (i-6 < Length) {
+/* expected-warning {{extra tokens at end of '#pragma clang loop vectorize' - ignored}}*/ while (i-6 < Length) {
     List[i] = i;
   }
 
 #pragma clang loop interleave(enable, extra)
-/* expected-warning {{extra tokens at end of '#pragma clang loop loop' - ignored}}*/ while (i-6 < Length) {
+/* expected-warning {{extra tokens at end of '#pragma clang loop interleave' - ignored}}*/ while (i-6 < Length) {
     List[i] = i;
   }
 
 #pragma clang loop unroll(enable, extra)
-/* expected-warning {{extra tokens at end of '#pragma clang loop loop' - ignored}}*/ while (i-6 < Length) {
+/* expected-warning {{extra tokens at end of '#pragma clang loop unroll' - ignored}}*/ while (i-6 < Length) {
     List[i] = i;
   }
 
 #pragma clang loop vectorize_predicate(enable, extra)
-/* expected-warning {{extra tokens at end of '#pragma clang loop loop' - ignored}}*/ while (i-6 < Length) {
+/* expected-warning {{extra tokens at end of '#pragma clang loop vectorize_predicate' - ignored}}*/ while (i-6 < Length) {
     List[i] = i;
   }
 
 #pragma clang loop pipeline(disable, extra)
-/* expected-warning {{extra tokens at end of '#pragma clang loop loop' - ignored}}*/ while (i-6 < Length) {
+/* expected-warning {{extra tokens at end of '#pragma clang loop pipeline' - ignored}}*/ while (i-6 < Length) {
     List[i] = i;
   }
 
-/* expected-warning {{extra tokens at end of '#pragma clang loop loop' - ignored}}*/ #pragma clang loop vectorize_width(2, scalable, extra)
-/* expected-warning {{extra tokens at end of '#pragma clang loop loop' - ignored}}*/ #pragma clang loop interleave_count(2, extra)
-/* expected-warning {{extra tokens at end of '#pragma clang loop loop' - ignored}}*/ #pragma clang loop unroll_count(2, extra)
-/* expected-warning {{extra tokens at end of '#pragma clang loop loop' - ignored}}*/ #pragma clang loop pipeline_initiation_interval(2, extra)
+/* expected-warning {{extra tokens at end of '#pragma clang loop vectorize_width' - ignored}}*/ #pragma clang loop vectorize_width(2, scalable, extra)
+/* expected-warning {{extra tokens at end of '#pragma clang loop interleave_count' - ignored}}*/ #pragma clang loop interleave_count(2, extra)
+/* expected-warning {{extra tokens at end of '#pragma clang loop unroll_count' - ignored}}*/ #pragma clang loop unroll_count(2, extra)
+/* expected-warning {{extra tokens at end of '#pragma clang loop pipeline_initiation_interval' - ignored}}*/ #pragma clang loop pipeline_initiation_interval(2, extra)
   while (i-6 < Length) {
     List[i] = i;
   }
 }