[clang] Use a StringRef instead of a raw char pointer to store builtin and call information

This avoids recomputing string length that is already known at compile time.

It has a slight impact on preprocessing / compile time, see

https://llvm-compile-time-tracker.com/compare.php?from=3f36d2d579d8b0e8824d9dd99bfa79f456858f88&to=e49640c507ddc6615b5e503144301c8e41f8f434&stat=instructions:u

This a recommit of e953ae5bbc313fd0cc980ce021d487e5b5199ea4 and the subsequent fixes caa713559bd38f337d7d35de35686775e8fb5175 and 06b90e2e9c991e211fecc97948e533320a825470.

The above patchset caused some version of GCC to take eons to compile clang/lib/Basic/Targets/AArch64.cpp, as spotted in aa171833ab0017d9732e82b8682c9848ab25ff9e.
The fix is to make BuiltinInfo tables a compilation unit static variable, instead of a private static variable.

Differential Revision: https://reviews.llvm.org/D139881

1 files changed, 15 insertions, 25 deletions

diff --git a/llvm/lib/Option/OptTable.cpp b/llvm/lib/Option/OptTable.cpp
index 786760f..c21072b 100644
--- a/llvm/lib/Option/OptTable.cpp
+++ b/llvm/lib/Option/OptTable.cpp
@@ -62,12 +62,10 @@ static inline bool operator<(const OptTable::Info &A, const OptTable::Info &B) {
   if (int N = StrCmpOptionName(A.Name, B.Name))
     return N < 0;
 
-  for (const char * const *APre = A.Prefixes,
-                  * const *BPre = B.Prefixes;
-                          *APre != nullptr && *BPre != nullptr; ++APre, ++BPre){
-    if (int N = StrCmpOptionName(*APre, *BPre))
+  for (size_t I = 0, K = std::min(A.Prefixes.size(), B.Prefixes.size()); I != K;
+       ++I)
+    if (int N = StrCmpOptionName(A.Prefixes[I], B.Prefixes[I]))
       return N < 0;
-  }
 
   // Names are the same, check that classes are in order; exactly one
   // should be joined, and it should succeed the other.
@@ -131,11 +129,8 @@ OptTable::OptTable(ArrayRef<Info> OptionInfos, bool IgnoreCase)
   // Build prefixes.
   for (unsigned i = FirstSearchableIndex + 1, e = getNumOptions() + 1;
                 i != e; ++i) {
-    if (const char *const *P = getInfo(i).Prefixes) {
-      for (; *P != nullptr; ++P) {
-        PrefixesUnion.insert(*P);
-      }
-    }
+    const auto &P = getInfo(i).Prefixes;
+    PrefixesUnion.insert(P.begin(), P.end());
   }
 
   // Build prefix chars.
@@ -168,8 +163,7 @@ static bool isInput(const StringSet<> &Prefixes, StringRef Arg) {
 /// \returns Matched size. 0 means no match.
 static unsigned matchOption(const OptTable::Info *I, StringRef Str,
                             bool IgnoreCase) {
-  for (const char * const *Pre = I->Prefixes; *Pre != nullptr; ++Pre) {
-    StringRef Prefix(*Pre);
+  for (auto Prefix : I->Prefixes) {
     if (Str.startswith(Prefix)) {
       StringRef Rest = Str.substr(Prefix.size());
       bool Matched = IgnoreCase ? Rest.startswith_insensitive(I->Name)
@@ -183,13 +177,10 @@ static unsigned matchOption(const OptTable::Info *I, StringRef Str,
 
 // Returns true if one of the Prefixes + In.Names matches Option
 static bool optionMatches(const OptTable::Info &In, StringRef Option) {
-  if (In.Prefixes) {
-    StringRef InName(In.Name);
-    for (size_t I = 0; In.Prefixes[I]; I++)
-      if (Option.endswith(InName))
-        if (Option.slice(0, Option.size() - InName.size()) == In.Prefixes[I])
-          return true;
-  }
+  for (auto Prefix : In.Prefixes)
+    if (Option.endswith(In.Name))
+      if (Option.slice(0, Option.size() - In.Name.size()) == Prefix)
+        return true;
   return false;
 }
 
@@ -221,13 +212,13 @@ OptTable::findByPrefix(StringRef Cur, unsigned int DisableFlags) const {
   std::vector<std::string> Ret;
   for (size_t I = FirstSearchableIndex, E = OptionInfos.size(); I < E; I++) {
     const Info &In = OptionInfos[I];
-    if (!In.Prefixes || (!In.HelpText && !In.GroupID))
+    if (In.Prefixes.empty() || (!In.HelpText && !In.GroupID))
       continue;
     if (In.Flags & DisableFlags)
       continue;
 
-    for (int I = 0; In.Prefixes[I]; I++) {
-      std::string S = std::string(In.Prefixes[I]) + std::string(In.Name) + "\t";
+    for (auto Prefix : In.Prefixes) {
+      std::string S = (Prefix + In.Name + "\t").str();
       if (In.HelpText)
         S += In.HelpText;
       if (StringRef(S).startswith(Cur) && S != std::string(Cur) + "\t")
@@ -265,7 +256,7 @@ unsigned OptTable::findNearest(StringRef Option, std::string &NearestString,
 
     // * Ignore positional argument option candidates (which do not
     //   have prefixes).
-    if (!CandidateInfo.Prefixes)
+    if (CandidateInfo.Prefixes.empty())
       continue;
 
     // Now check if the candidate ends with a character commonly used when
@@ -285,8 +276,7 @@ unsigned OptTable::findNearest(StringRef Option, std::string &NearestString,
     // Consider each possible prefix for each candidate to find the most
     // appropriate one. For example, if a user asks for "--helm", suggest
     // "--help" over "-help".
-    for (int P = 0;
-         const char *const CandidatePrefix = CandidateInfo.Prefixes[P]; P++) {
+    for (auto CandidatePrefix : CandidateInfo.Prefixes) {
       std::string Candidate = (CandidatePrefix + CandidateName).str();
       StringRef CandidateRef = Candidate;
       unsigned Distance =