1 files changed, 23 insertions, 8 deletions
diff --git a/include/llvm/Transforms/Scalar/LoopUnrollPass.h b/include/llvm/Transforms/Scalar/LoopUnrollPass.h
index e38e983cc9eb..a84d889a83ad 100644
--- a/include/llvm/Transforms/Scalar/LoopUnrollPass.h
+++ b/include/llvm/Transforms/Scalar/LoopUnrollPass.h
@@ -1,9 +1,8 @@
 //===- LoopUnrollPass.h -----------------------------------------*- C++ -*-===//
 //
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
+// 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
 //
 //===----------------------------------------------------------------------===//
 
@@ -16,6 +15,8 @@
 
 namespace llvm {
 
+extern cl::opt<bool> ForgetSCEVInLoopUnroll;
+
 class Function;
 class Loop;
 class LPMUpdater;
@@ -29,9 +30,16 @@ class LoopFullUnrollPass : public PassInfoMixin<LoopFullUnrollPass> {
   /// metadata are considered. All other loops are skipped.
   const bool OnlyWhenForced;
 
+  /// If true, forget all loops when unrolling. If false, forget top-most loop
+  /// of the currently processed loops, which removes one entry at a time from
+  /// the internal SCEV records. For large loops, the former is faster.
+  const bool ForgetSCEV;
+
 public:
-  explicit LoopFullUnrollPass(int OptLevel = 2, bool OnlyWhenForced = false)
-      : OptLevel(OptLevel), OnlyWhenForced(OnlyWhenForced) {}
+  explicit LoopFullUnrollPass(int OptLevel = 2, bool OnlyWhenForced = false,
+                              bool ForgetSCEV = false)
+      : OptLevel(OptLevel), OnlyWhenForced(OnlyWhenForced),
+        ForgetSCEV(ForgetSCEV) {}
 
   PreservedAnalyses run(Loop &L, LoopAnalysisManager &AM,
                         LoopStandardAnalysisResults &AR, LPMUpdater &U);
@@ -61,8 +69,15 @@ struct LoopUnrollOptions {
   /// metadata are considered. All other loops are skipped.
   bool OnlyWhenForced;
 
-  LoopUnrollOptions(int OptLevel = 2, bool OnlyWhenForced = false)
-      : OptLevel(OptLevel), OnlyWhenForced(OnlyWhenForced) {}
+  /// If true, forget all loops when unrolling. If false, forget top-most loop
+  /// of the currently processed loops, which removes one entry at a time from
+  /// the internal SCEV records. For large loops, the former is faster.
+  const bool ForgetSCEV;
+
+  LoopUnrollOptions(int OptLevel = 2, bool OnlyWhenForced = false,
+                    bool ForgetSCEV = false)
+      : OptLevel(OptLevel), OnlyWhenForced(OnlyWhenForced),
+        ForgetSCEV(ForgetSCEV) {}
 
   /// Enables or disables partial unrolling. When disabled only full unrolling
   /// is allowed.