[clangd] Disable msan instrumentation for generated Evaluate().

[usaxena95]

Summary

MSAN build times out for generated DecisionForest inference runtime.

A solution worth trying is splitting the function into 300 smaller
functions and then re-enable msan.

For now we are disabling instrumentation for the generated function.

[adamcz]

clang-tools-extra/clangd/quality/CompletionModelCodegen.py

164

Please add a comment here explaining why this is disabled.

[usaxena95]

Addressed comments.

clang-tools-extra/clangd/quality/CompletionModelCodegen.py

def gen_header_code(features_json, cpp_class, filename):
     # Class members represent all the features of the Example.
     class_members = ["uint32_t %s = 0;" % f['name'] for f in features_json]
 
     nline = "\n  "
     guard = header_guard(filename)
     return """#ifndef %s
 #define %s
 #include <cstdint>
+#include "llvm/Support/Compiler.h"
 
 %s
 class %s {
 public:
   %s
 
 private:
   %s
 
   // Produces an integer that sorts in the same order as F.
   // That is: a < b <==> orderEncode(a) < orderEncode(b).
   static uint32_t OrderEncode(float F);
   friend float Evaluate(const %s&);
 };
 
+// The function may have large number of lines of code. MSAN
+// build times out in such case.
+LLVM_NO_SANITIZE("memory")
 float Evaluate(const %s&);
 %s
 #endif // %s
 """ % (guard, guard, cpp_class.ns_begin(), cpp_class.name, nline.join(setters),
         nline.join(class_members), cpp_class.name, cpp_class.name,
         cpp_class.ns_end(), guard)