[llvm] [LV][VPlan] Add initial support for CSA vectorization (PR #106560)

[Ramkumar Ramachandra via llvm-commits]

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@@ -0,0 +1,73 @@
+//=== llvm/Analysis/CSADescriptors.cpp - CSA Descriptors -*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file "describes" conditional scalar assignments (CSA).
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Analysis/CSADescriptors.h"
+#include "llvm/IR/PatternMatch.h"
+#include "llvm/IR/Type.h"
+
+using namespace llvm;
+using namespace llvm::PatternMatch;
+
+#define DEBUG_TYPE "csa-descriptors"
+
+CSADescriptor CSADescriptor::isCSAPhi(PHINode *Phi, Loop *TheLoop) {
+  // Return CSADescriptor that describes a CSA that matches one of these
+  // patterns:
+  //   phi loop_inv, (select cmp, value, phi)
+  //   phi loop_inv, (select cmp, phi, value)
+  //   phi (select cmp, value, phi), loop_inv
+  //   phi (select cmp, phi, value), loop_inv
+  // If the CSA does not match any of these paterns, return a CSADescriptor
+  // that describes an InvalidCSA.
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artagnon wrote:

Move above function declaration (one line), and use `///`?

https://github.com/llvm/llvm-project/pull/106560