Simplify name reversal, add # to separate name from number (#48710)

src/cgutils.cpp

@@ -325,29 +325,29 @@ static Value *julia_pgv(jl_codectx_t &ctx, const char *cname, void *addr)
 static Value *julia_pgv(jl_codectx_t &ctx, const char *prefix, jl_sym_t *name, jl_module_t *mod, void *addr)
 {
  // emit a GlobalVariable for a jl_value_t, using the prefix, name, and module to
- // to create a readable name of the form prefixModA.ModB.name
- size_t len = strlen(jl_symbol_name(name)) + strlen(prefix) + 1;
+ // to create a readable name of the form prefixModA.ModB.name#
+ // reverse-of-reverse algorithm
+ std::string finalname;
+ StringRef name_str(jl_symbol_name(name));
+ finalname.resize(name_str.size() + 1);
+ finalname[0] = '#';
+ std::reverse_copy(name_str.begin(), name_str.end(), finalname.begin() + 1);
  jl_module_t *parent = mod, *prev = NULL;
- while (parent != NULL && parent != prev) {
- len += strlen(jl_symbol_name(parent->name))+1;
+ while (parent && parent != prev) {
+ size_t orig_end = finalname.size() + 1;
+ StringRef parent_name(jl_symbol_name(parent->name));
+ finalname.resize(orig_end + parent_name.size());
+ finalname[orig_end - 1] = '.';
+ std::reverse_copy(parent_name.begin(), parent_name.end(), finalname.begin() + orig_end);
  prev = parent;
  parent = parent->parent;
  }
- char *fullname = (char*)alloca(len);
- strcpy(fullname, prefix);
- len -= strlen(jl_symbol_name(name)) + 1;
- strcpy(fullname + len, jl_symbol_name(name));
- parent = mod;
- prev = NULL;
- while (parent != NULL && parent != prev) {
- size_t part = strlen(jl_symbol_name(parent->name)) + 1;
- strcpy(fullname + len - part, jl_symbol_name(parent->name));
- fullname[len - 1] = '.';
- len -= part;
- prev = parent;
- parent = parent->parent;
- }
- return julia_pgv(ctx, fullname, addr);
+ size_t orig_end = finalname.size();
+ StringRef prefix_name(prefix);
+ finalname.resize(orig_end + prefix_name.size());
+ std::reverse_copy(prefix_name.begin(), prefix_name.end(), finalname.begin() + orig_end);
+ std::reverse(finalname.begin(), finalname.end());
+ return julia_pgv(ctx, finalname.c_str(), addr);
 }
 
 static JuliaVariable *julia_const_gv(jl_value_t *val);