[llvm] [SVE] Don't require lookup when demangling vector function mappings (PR #72260)

[Paul Walker via llvm-commits]

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@@ -374,6 +424,24 @@ std::optional<VFInfo> VFABI::tryDemangleForVFABI(StringRef MangledName,
   if (Parameters.empty())
     return std::nullopt;
 
+  // Figure out the number of lanes in vectors for this function variant. This
+  // is easy for fixed length, as the vlen encoding just gives us the value
+  // directly. However, if the vlen mangling indicated that this function
+  // variant expects scalable vectors, then we need to figure out the minimum
+  // based on the widest scalar types in vector arguments.
+  std::optional<ElementCount> EC;
+  if (ParsedVF.second) {
+    // Scalable VF, need to work out the minimum from the element types
+    // in the scalar function arguments.
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paulwalker-arm wrote:

As above, although personally I'd just remove this comment as the function name tells the reader all they need to know.

https://github.com/llvm/llvm-project/pull/72260