[llvm] [llvm] Improve implementation of StringRef::find_last_of and cie (PR #71865)

[Alexandre Ganea via llvm-commits]

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@@ -268,17 +272,44 @@ StringRef::size_type StringRef::find_first_not_of(StringRef Chars,
   return npos;
 }
 
+#ifdef __SSE2__
+
+StringRef::size_type vectorized_find_last_of_specialized(const char *Data,
+                                                         size_t Sz, char C0,
+                                                         char C1) {
+  __m128i Needle0 = _mm_set1_epi8(C0);
+  __m128i Needle1 = _mm_set1_epi8(C1);
+  do {
+    Sz = Sz < 16 ? 0 : Sz - 16;
+    __m128i Buffer = _mm_loadu_si128((const __m128i *)(Data + Sz));
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aganea wrote:

This load instruction will generate an out-of-bounds access if `strlen(Data)<15`.  Do you think you can use the "slow" algorithm when that happens?

https://github.com/llvm/llvm-project/pull/71865