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

[Alex MacLean 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 << "_$_";
-    } else {
+    if (isAlnum(C) || C == '_' || C == '$') {
       ValidNameStream << C;
+    } else {
+      ValidNameStream << "_$_";
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AlexMaclean wrote:

`setName` will add a postfix number to avoid collisions, so I think correctness is fine. Do you think adding the hex values in necessary for readability? I agree the current renaming leaves much to be desired but the hex scheme suggested will also have ambiguous cases. (i.e. `str.` and `str$2E`)

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