[PM] Port IndVarSimplify to the new pass manager

[sanjoy]

Summary

There are some rough corners, since the new pass manager doesn't have
(as far as I can tell) LoopSimplify and LCSSA, so I've updated the
tests to run them separately in the old pass manager in the lit tests.

[davide]

The general structure looks fine to me. I left a comment for something that we should take care of (but we can't yet).
Would love to get a second opinion on it.

Thanks!

lib/Transforms/Scalar/IndVarSimplify.cpp

2238

The old PM 'preserves the CFG'. We can't do that yet in the new PM. Can you please add a FIXME here so we won't forget?

[chandlerc]

LGTM

lib/Transforms/Scalar/IndVarSimplify.cpp

2238

Yea, good to add a FIXME.

include/llvm/Transforms/Scalar/IndVarSimplify.h

+//===- IndVarSimplify.h - Induction Variable Simplification -----*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file provides the interface for the Induction Variable
+// Simplification pass.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_SCALAR_INDVARSIMPLIFY_H
+#define LLVM_TRANSFORMS_SCALAR_INDVARSIMPLIFY_H
+
+#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/IR/PassManager.h"
+
+namespace llvm {
+
+class IndVarSimplifyPass : public PassInfoMixin<IndVarSimplifyPass> {
+public:
+  PreservedAnalyses run(Loop &L, AnalysisManager<Loop> &AM);
+};
+}
+
+#endif // LLVM_TRANSFORMS_SCALAR_INDVARSIMPLIFY_H

lib/Passes/PassBuilder.cpp

 #include "llvm/Transforms/SampleProfile.h"
 #include "llvm/Transforms/Scalar/ADCE.h"
 #include "llvm/Transforms/Scalar/BDCE.h"
 #include "llvm/Transforms/Scalar/DCE.h"
 #include "llvm/Transforms/Scalar/DeadStoreElimination.h"
 #include "llvm/Transforms/Scalar/EarlyCSE.h"
 #include "llvm/Transforms/Scalar/GVN.h"
 #include "llvm/Transforms/Scalar/GuardWidening.h"
+#include "llvm/Transforms/Scalar/IndVarSimplify.h"
 #include "llvm/Transforms/Scalar/LoopRotation.h"
 #include "llvm/Transforms/Scalar/LoopSimplifyCFG.h"
 #include "llvm/Transforms/Scalar/LowerAtomic.h"
 #include "llvm/Transforms/Scalar/LowerExpectIntrinsic.h"
 #include "llvm/Transforms/Scalar/PartiallyInlineLibCalls.h"
 #include "llvm/Transforms/Scalar/Reassociate.h"
 #include "llvm/Transforms/Scalar/SCCP.h"
 #include "llvm/Transforms/Scalar/SROA.h"

lib/Passes/PassRegistry.def

 #ifndef LOOP_PASS
 #define LOOP_PASS(NAME, CREATE_PASS)
 #endif
 LOOP_PASS("invalidate<all>", InvalidateAllAnalysesPass())
 LOOP_PASS("rotate", LoopRotatePass())
 LOOP_PASS("no-op-loop", NoOpLoopPass())
 LOOP_PASS("print", PrintLoopPass(dbgs()))
 LOOP_PASS("simplify-cfg", LoopSimplifyCFGPass())
+LOOP_PASS("indvars", IndVarSimplifyPass())
 #undef LOOP_PASS

lib/Transforms/Scalar/IndVarSimplify.cpp

 //   2. Any use outside of the loop of an expression derived from the indvar
 //      is changed to compute the derived value outside of the loop, eliminating
 //      the dependence on the exit value of the induction variable.  If the only
 //      purpose of the loop is to compute the exit value of some derived
 //      expression, this transformation will make the loop dead.
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm/Transforms/Scalar/IndVarSimplify.h"
 #include "llvm/Transforms/Scalar.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/Analysis/GlobalsModRef.h"
 #include "llvm/Analysis/LoopInfo.h"
 #include "llvm/Analysis/LoopPass.h"
+#include "llvm/Analysis/LoopPassManager.h"
 #include "llvm/Analysis/ScalarEvolutionExpander.h"
 #include "llvm/Analysis/ScalarEvolutionAliasAnalysis.h"
 #include "llvm/Analysis/TargetLibraryInfo.h"
 #include "llvm/Analysis/TargetTransformInfo.h"
 #include "llvm/IR/BasicBlock.h"
 #include "llvm/IR/CFG.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/DataLayout.h"
else
                                                  NewBECount->getType());
     assert(BackedgeTakenCount == NewBECount && "indvars must preserve SCEV");
   }
 #endif
 
   return Changed;
 }
 
+PreservedAnalyses IndVarSimplifyPass::run(Loop &L, AnalysisManager<Loop> &AM) {
+  auto &FAM = AM.getResult<FunctionAnalysisManagerLoopProxy>(L).getManager();
+  Function *F = L.getHeader()->getParent();
+  const DataLayout &DL = F->getParent()->getDataLayout();
+
+  auto *LI = FAM.getCachedResult<LoopAnalysis>(*F);
+  auto *SE = FAM.getCachedResult<ScalarEvolutionAnalysis>(*F);
+  auto *DT = FAM.getCachedResult<DominatorTreeAnalysis>(*F);
+
+  assert((LI && SE && DT) &&
+         "Analyses required for indvarsimplify not available!");
+
+  // Optional analyses.
+  auto *TTI = FAM.getCachedResult<TargetIRAnalysis>(*F);
+  auto *TLI = FAM.getCachedResult<TargetLibraryAnalysis>(*F);
+
+  IndVarSimplify IVS(LI, SE, DT, DL, TLI, TTI);
+  if (!IVS.run(&L))
+    return PreservedAnalyses::all();
+
+  return getLoopPassPreservedAnalyses();
+}
+
 namespace {
 struct IndVarSimplifyLegacyPass : public LoopPass {
   static char ID; // Pass identification, replacement for typeid
   IndVarSimplifyLegacyPass() : LoopPass(ID) {
     initializeIndVarSimplifyLegacyPassPass(*PassRegistry::getPassRegistry());
   }
 
   bool runOnLoop(Loop *L, LPPassManager &LPM) override {

test/Transforms/IndVarSimplify/backedge-on-min-max.ll

 ; RUN: opt < %s -indvars -S | FileCheck %s
+; RUN: opt -lcssa -loop-simplify -S < %s | opt -S -passes='require<targetir>,require<scalar-evolution>,require<domtree>,loop(indvars)'
 
 ;; --- signed ---
 
 define void @min.signed.1(i32* %a, i32 %a_len, i32 %n) {
 ; CHECK-LABEL: @min.signed.1
  entry:
   %smin.cmp = icmp slt i32 %a_len, %n
   %smin = select i1 %smin.cmp, i32 %a_len, i32 %n

test/Transforms/IndVarSimplify/iv-widen.ll

 ; RUN: opt < %s -indvars -S | FileCheck %s
+; RUN: opt -lcssa -loop-simplify -S < %s | opt -S -passes='require<targetir>,require<scalar-evolution>,require<domtree>,loop(indvars)'
 
 ; Provide legal integer types.
 target datalayout = "n8:16:32:64"
 
 
 target triple = "x86_64-apple-darwin"
 
 ; CHECK-LABEL: @loop_0

test/Transforms/IndVarSimplify/sharpen-range.ll

 ;; RUN: opt -S < %s -indvars | FileCheck %s
+; RUN: opt -lcssa -loop-simplify -S < %s | opt -S -passes='require<targetir>,require<scalar-evolution>,require<domtree>,loop(indvars)'
 
 ;; Check if llvm can narrow !range metadata based on loop entry
 ;; predicates.
 
 declare void @abort()
 
 define i1 @bounded_below_slt(i32* nocapture readonly %buffer) {
 ; CHECK-LABEL: bounded_below_slt