Fix a bug in TableGen where the intrinsic function name recognizer could mis-identify names if one was a prefix substring of the other

For two intrinsics 'llvm.nvvm.texsurf.handle' and 'llvm.nvvm.texsurf.handle.internal',
TableGen was emitting matching code like:

  if (Name.startswith("llvm.nvvm.texsurf.handle")) ...
  if (Name.startswith("llvm.nvvm.texsurf.handle.internal")) ...

We can never match "llvm.nvvm.texsurf.handle.internal" here because it will
always be erroneously matched by the first condition.

The fix is to sort the intrinsic names and emit them in reverse order.

llvm-svn: 187119

1 files changed, 18 insertions, 0 deletions

diff --git a/llvm/utils/TableGen/IntrinsicEmitter.cpp b/llvm/utils/TableGen/IntrinsicEmitter.cpp
index c83797c25df..c508795cc88 100644
--- a/llvm/utils/TableGen/IntrinsicEmitter.cpp
+++ b/llvm/utils/TableGen/IntrinsicEmitter.cpp
@@ -131,6 +131,20 @@ void IntrinsicEmitter::EmitEnumInfo(const std::vector<CodeGenIntrinsic> &Ints,
   OS << "#endif\n\n";
 }
 
+struct IntrinsicNameSorter {
+  IntrinsicNameSorter(const std::vector<CodeGenIntrinsic> &I)
+  : Ints(I) {}
+
+  // Sort in reverse order of intrinsic name so "abc.def" appears after
+  // "abd.def.ghi" in the overridden name matcher
+  bool operator()(unsigned i, unsigned j) {
+    return Ints[i].Name > Ints[j].Name;
+  }
+
+private:
+  const std::vector<CodeGenIntrinsic> &Ints;
+};
+
 void IntrinsicEmitter::
 EmitFnNameRecognizer(const std::vector<CodeGenIntrinsic> &Ints, 
                      raw_ostream &OS) {
@@ -144,12 +158,16 @@ EmitFnNameRecognizer(const std::vector<CodeGenIntrinsic> &Ints,
   OS << "  StringRef NameR(Name+6, Len-6);   // Skip over 'llvm.'\n";
   OS << "  switch (Name[5]) {                  // Dispatch on first letter.\n";
   OS << "  default: break;\n";
+  IntrinsicNameSorter Sorter(Ints);
   // Emit the intrinsic matching stuff by first letter.
   for (std::map<char, std::vector<unsigned> >::iterator I = IntMapping.begin(),
        E = IntMapping.end(); I != E; ++I) {
     OS << "  case '" << I->first << "':\n";
     std::vector<unsigned> &IntList = I->second;
 
+    // Sort intrinsics in reverse order of their names
+    std::sort(IntList.begin(), IntList.end(), Sorter);
+
     // Emit all the overloaded intrinsics first, build a table of the
     // non-overloaded ones.
     std::vector<StringMatcher::StringPair> MatchTable;