[Core] Skip over target name in intrinsic name lookup (#109971)

When searching for an intrinsic name in a target specific slice of the
intrinsic name table, skip over the target prefix. For such cases,
currently the first loop iteration in `lookupLLVMIntrinsicByName` does
nothing (i.e., `Low` and `High` stay unchanged and it does not shrink
down the search window), so we can skip this useless first iteration by
skipping over the target prefix.

1 files changed, 10 insertions, 9 deletions

diff --git a/llvm/lib/IR/Function.cpp b/llvm/lib/IR/Function.cpp
index 8767c29..863900c 100644
--- a/llvm/lib/IR/Function.cpp
+++ b/llvm/lib/IR/Function.cpp
@@ -940,8 +940,8 @@ void Function::setOnlyAccessesInaccessibleMemOrArgMem() {
 }
 
 /// Table of string intrinsic names indexed by enum value.
-static const char * const IntrinsicNameTable[] = {
-  "not_intrinsic",
+static constexpr const char *const IntrinsicNameTable[] = {
+    "not_intrinsic",
 #define GET_INTRINSIC_NAME_TABLE
 #include "llvm/IR/IntrinsicImpl.inc"
 #undef GET_INTRINSIC_NAME_TABLE
@@ -963,8 +963,9 @@ bool Function::isTargetIntrinsic() const {
 /// Find the segment of \c IntrinsicNameTable for intrinsics with the same
 /// target as \c Name, or the generic table if \c Name is not target specific.
 ///
-/// Returns the relevant slice of \c IntrinsicNameTable
-static ArrayRef<const char *> findTargetSubtable(StringRef Name) {
+/// Returns the relevant slice of \c IntrinsicNameTable and the target name.
+static std::pair<ArrayRef<const char *>, StringRef>
+findTargetSubtable(StringRef Name) {
   assert(Name.starts_with("llvm."));
 
   ArrayRef<IntrinsicTargetInfo> Targets(TargetInfos);
@@ -976,14 +977,14 @@ static ArrayRef<const char *> findTargetSubtable(StringRef Name) {
   // We've either found the target or just fall back to the generic set, which
   // is always first.
   const auto &TI = It != Targets.end() && It->Name == Target ? *It : Targets[0];
-  return ArrayRef(&IntrinsicNameTable[1] + TI.Offset, TI.Count);
+  return {ArrayRef(&IntrinsicNameTable[1] + TI.Offset, TI.Count), TI.Name};
 }
 
-/// This does the actual lookup of an intrinsic ID which
-/// matches the given function name.
+/// This does the actual lookup of an intrinsic ID which matches the given
+/// function name.
 Intrinsic::ID Function::lookupIntrinsicID(StringRef Name) {
-  ArrayRef<const char *> NameTable = findTargetSubtable(Name);
-  int Idx = Intrinsic::lookupLLVMIntrinsicByName(NameTable, Name);
+  auto [NameTable, Target] = findTargetSubtable(Name);
+  int Idx = Intrinsic::lookupLLVMIntrinsicByName(NameTable, Name, Target);
   if (Idx == -1)
     return Intrinsic::not_intrinsic;