Handle more edge cases in intrinsic name binary search

I tried to make the AMDGPU intrinsic info table use this instead of
another StringMatcher, and some issues arose.

llvm-svn: 258871

1 files changed, 1 insertions, 40 deletions

diff --git a/llvm/lib/IR/Function.cpp b/llvm/lib/IR/Function.cpp
index 4e08000..40a8ec6 100644
--- a/llvm/lib/IR/Function.cpp
+++ b/llvm/lib/IR/Function.cpp
@@ -414,53 +414,14 @@ static const char * const IntrinsicNameTable[] = {
 #undef GET_INTRINSIC_NAME_TABLE
 };
 
-static int lookupLLVMIntrinsicByName(ArrayRef<const char *> NameTable,
-                                     StringRef Name) {
-  // Do a binary search over the table of intrinsic names.
-  const char *const *NameEntry =
-      std::lower_bound(NameTable.begin(), NameTable.end(), Name.data(),
-                       [](const char *LHS, const char *RHS) {
-                         // Don't compare the first 5 characters, they are
-                         // always "llvm.".
-                         return strcmp(LHS + 5, RHS + 5) < 0;
-                       });
-  unsigned Idx = NameEntry - NameTable.begin();
-
-  // Check if this is a direct match.
-  if (Idx < NameTable.size() && strcmp(Name.data(), NameTable[Idx]) == 0)
-    return Idx;
-
-  // Otherwise, back up one entry to look for a prefix of Name where the next
-  // character in Name is a dot.
-  if (Idx == 0)
-    return -1;
-  --Idx;
-  bool CheckPrefixes = true;
-  while (CheckPrefixes) {
-    StringRef FoundName = NameTable[Idx];
-    if (Name.startswith(FoundName) && Name[FoundName.size()] == '.')
-      return Idx;
-    if (Idx == 0)
-      return -1;
-    --Idx;
-    // We have to keep scanning backwards until the previous entry is not a
-    // prefix of the current entry. Consider a key of llvm.foo.f64 and a table
-    // of llvm.foo and llvm.foo.bar.
-    CheckPrefixes = FoundName.startswith(NameTable[Idx]);
-  }
-
-  return -1;
-}
-
 /// \brief This does the actual lookup of an intrinsic ID which
 /// matches the given function name.
 static Intrinsic::ID lookupIntrinsicID(const ValueName *ValName) {
   StringRef Name = ValName->getKey();
-  assert(Name.data()[Name.size()] == '\0' && "non-null terminated ValueName");
 
   ArrayRef<const char *> NameTable(&IntrinsicNameTable[1],
                                    std::end(IntrinsicNameTable));
-  int Idx = lookupLLVMIntrinsicByName(NameTable, Name);
+  int Idx = Intrinsic::lookupLLVMIntrinsicByName(NameTable, Name);
   Intrinsic::ID ID = static_cast<Intrinsic::ID>(Idx + 1);
   if (ID == Intrinsic::not_intrinsic)
     return ID;