Added a SimplifyIndVar utility to simplify induction variable users

based on ScalarEvolution without changing the induction variable phis.

This utility is the main tool of IndVarSimplifyPass, but the pass also
restructures induction variables in strange ways that are sensitive to
pass ordering. This provides a way for other loop passes to simplify
new uses of induction variables created during transformation. The
utility may be used by any pass that preserves ScalarEvolution. Soon
LoopUnroll will use it.

The net effect in this checkin is to cleanup the IndVarSimplify pass
by factoring out the SimplifyIndVar algorithm into a standalone utility.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@137197 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 58 insertions, 0 deletions

diff --git a/include/llvm/Transforms/Utils/SimplifyIndVar.h b/include/llvm/Transforms/Utils/SimplifyIndVar.h
new file mode 100644
index 0000000..46e4aaf
--- /dev/null
+++ b/include/llvm/Transforms/Utils/SimplifyIndVar.h
@@ -0,0 +1,58 @@
+//===-- llvm/Transforms/Utils/SimplifyIndVar.h - Indvar Utils ---*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines in interface for induction variable simplification. It does
+// not define any actual pass or policy, but provides a single function to
+// simplify a loop's induction variables based on ScalarEvolution.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_UTILS_SIMPLIFYINDVAR_H
+#define LLVM_TRANSFORMS_UTILS_SIMPLIFYINDVAR_H
+
+#include "llvm/Support/CommandLine.h"
+
+namespace llvm {
+
+extern cl::opt<bool> DisableIVRewrite;
+
+class Loop;
+class LoopInfo;
+class DominatorTree;
+class ScalarEvolution;
+class LPPassManager;
+class IVUsers;
+
+/// Interface for visiting interesting IV users that are recognized but not
+/// simplified by this utility.
+class IVVisitor {
+public:
+  virtual ~IVVisitor() {}
+  virtual void visitCast(CastInst *Cast) = 0;
+};
+
+/// simplifyUsersOfIV - Simplify instructions that use this induction variable
+/// by using ScalarEvolution to analyze the IV's recurrence.
+bool simplifyUsersOfIV(PHINode *CurrIV, LPPassManager *LPM,
+                       SmallVectorImpl<WeakVH> &Dead, IVVisitor *V = NULL);
+
+/// SimplifyLoopIVs - Simplify users of induction variables within this
+/// loop. This does not actually change or add IVs.
+bool simplifyLoopIVs(Loop *L, LPPassManager *LPM,
+                     SmallVectorImpl<WeakVH> &Dead);
+
+/// simplifyIVUsers - Simplify instructions recorded by the IVUsers pass.
+/// This is a legacy implementation to reproduce the behavior of the
+/// IndVarSimplify pass prior to DisableIVRewrite.
+bool simplifyIVUsers(IVUsers *IU, LPPassManager *LPM,
+                     SmallVectorImpl<WeakVH> &Dead);
+
+} // namespace llvm
+
+#endif