[llvm] LoopIdiomRecognize: update comment about ctpop (NFC) (PR #70812)

[Ramkumar Ramachandra via llvm-commits]

https://github.com/artagnon created https://github.com/llvm/llvm-project/pull/70812

Ever since 95de7c3, LoopIdiomRecognize has been able to recognize the ctpop idiom, with target-specific lowering information. However, the comment in the header about ctpop not being recognized is outdated. Remove it.

>From 3c6b6b57d0ac4b2ccb7bfa9272fadd4b84c36433 Mon Sep 17 00:00:00 2001
From: Ramkumar Ramachandra <Ramkumar.Ramachandra at imgtec.com>
Date: Tue, 31 Oct 2023 14:24:58 +0000
Subject: [PATCH] LoopIdiomRecognize: update comment about ctpop (NFC)

Ever since 95de7c3, LoopIdiomRecognize has been able to recognize the
ctpop idiom, with target-specific lowering information. However, the
comment in the header about ctpop not being recognized is outdated.
Remove it.
---
 llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp b/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
index b85178585e0ada0..3b2a7b03dd6d34e 100644
--- a/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
@@ -24,12 +24,6 @@
 //   memcmp, strlen, etc.
 // Future floating point idioms to recognize in -ffast-math mode:
 //   fpowi
-// Future integer operation idioms to recognize:
-//   ctpop
-//
-// Beware that isel's default lowering for ctpop is highly inefficient for
-// i64 and larger types when i64 is legal and the value has few bits set.  It
-// would be good to enhance isel to emit a loop for ctpop in this case.
 //
 // This could recognize common matrix multiplies and dot product idioms and
 // replace them with calls to BLAS (if linked in??).