[llvm] [NVPTX] improve identifier renaming for PTX (PR #79459)

[Artem Belevich via llvm-commits]

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@@ -73,10 +74,10 @@ std::string NVPTXAssignValidGlobalNames::cleanUpName(StringRef Name) {
   std::string ValidName;
   raw_string_ostream ValidNameStream(ValidName);
   for (char C : Name) {
-    if (C == '.' || C == '@' || C == '<' || C == '>') {
-      ValidNameStream << "_$_";
-    } else {
+    if (isAlnum(C) || C == '_' || C == '$') {
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Artem-B wrote:

PTX also allows '%' as the first character:
https://docs.nvidia.com/cuda/parallel-thread-execution/index.html#identifiers
> followsym:   [a-zA-Z0-9_$]
> identifier:  [a-zA-Z]{followsym}* | {[_$%]{followsym}+


https://github.com/llvm/llvm-project/pull/79459