[llvm] dc28675 - Revert "[SCEVExpander] Add option to preserve LCSSA directly."

Florian Hahn via llvm-commits llvm-commits at lists.llvm.org
Wed Jul 29 11:19:22 PDT 2020


Author: Florian Hahn
Date: 2020-07-29T19:19:04+01:00
New Revision: dc2867576886247cbe351e7c63618c09ab6af808

URL: https://github.com/llvm/llvm-project/commit/dc2867576886247cbe351e7c63618c09ab6af808
DIFF: https://github.com/llvm/llvm-project/commit/dc2867576886247cbe351e7c63618c09ab6af808.diff

LOG: Revert "[SCEVExpander] Add option to preserve LCSSA directly."

This reverts commit 99166fd4fb422351f131fb1265cb85d5f6c5b8da, because it
breaks the polly builders.

polly/test/Isl/CodeGen/invariant_load_escaping_second_scop.ll fails
because a apparently unnecessary LCSSA phi node is introduced.

Make the bots green again, while I take a closer look.

Added: 
    

Modified: 
    llvm/include/llvm/Transforms/Utils/ScalarEvolutionExpander.h
    llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
    llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
    llvm/unittests/Transforms/Utils/ScalarEvolutionExpanderTest.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/Transforms/Utils/ScalarEvolutionExpander.h b/llvm/include/llvm/Transforms/Utils/ScalarEvolutionExpander.h
index cb212b2705ee..6e53d15d25fc 100644
--- a/llvm/include/llvm/Transforms/Utils/ScalarEvolutionExpander.h
+++ b/llvm/include/llvm/Transforms/Utils/ScalarEvolutionExpander.h
@@ -52,9 +52,6 @@ class SCEVExpander : public SCEVVisitor<SCEVExpander, Value *> {
   // New instructions receive a name to identify them with the current pass.
   const char *IVName;
 
-  /// Indicates whether LCSSA phis should be created for inserted values.
-  bool PreserveLCSSA;
-
   // InsertedExpressions caches Values for reuse, so must track RAUW.
   DenseMap<std::pair<const SCEV *, Instruction *>, TrackingVH<Value>>
       InsertedExpressions;
@@ -149,10 +146,9 @@ class SCEVExpander : public SCEVVisitor<SCEVExpander, Value *> {
 public:
   /// Construct a SCEVExpander in "canonical" mode.
   explicit SCEVExpander(ScalarEvolution &se, const DataLayout &DL,
-                        const char *name, bool PreserveLCSSA = true)
-      : SE(se), DL(DL), IVName(name), PreserveLCSSA(PreserveLCSSA),
-        IVIncInsertLoop(nullptr), IVIncInsertPos(nullptr), CanonicalMode(true),
-        LSRMode(false),
+                        const char *name)
+      : SE(se), DL(DL), IVName(name), IVIncInsertLoop(nullptr),
+        IVIncInsertPos(nullptr), CanonicalMode(true), LSRMode(false),
         Builder(se.getContext(), TargetFolder(DL),
                 IRBuilderCallbackInserter(
                     [this](Instruction *I) { rememberInstruction(I); })) {
@@ -227,18 +223,14 @@ class SCEVExpander : public SCEVVisitor<SCEVExpander, Value *> {
                                const TargetTransformInfo *TTI = nullptr);
 
   /// Insert code to directly compute the specified SCEV expression into the
-  /// program.  The code is inserted into the specified block.
-  Value *expandCodeFor(const SCEV *SH, Type *Ty, Instruction *I) {
-    return expandCodeForImpl(SH, Ty, I, true);
-  }
+  /// program.  The inserted code is inserted into the specified block.
+  Value *expandCodeFor(const SCEV *SH, Type *Ty, Instruction *I);
 
   /// Insert code to directly compute the specified SCEV expression into the
-  /// program.  The code is inserted into the SCEVExpander's current
+  /// program.  The inserted code is inserted into the SCEVExpander's current
   /// insertion point. If a type is specified, the result will be expanded to
   /// have that type, with a cast if necessary.
-  Value *expandCodeFor(const SCEV *SH, Type *Ty = nullptr) {
-    return expandCodeForImpl(SH, Ty, true);
-  }
+  Value *expandCodeFor(const SCEV *SH, Type *Ty = nullptr);
 
   /// Generates a code sequence that evaluates this predicate.  The inserted
   /// instructions will be at position \p Loc.  The result will be of type i1
@@ -346,20 +338,6 @@ class SCEVExpander : public SCEVVisitor<SCEVExpander, Value *> {
 private:
   LLVMContext &getContext() const { return SE.getContext(); }
 
-  /// Insert code to directly compute the specified SCEV expression into the
-  /// program. The code is inserted into the SCEVExpander's current
-  /// insertion point. If a type is specified, the result will be expanded to
-  /// have that type, with a cast if necessary. If \p Root is true, this
-  /// indicates that \p SH is the top-level expression to expand passed from
-  /// an external client call.
-  Value *expandCodeForImpl(const SCEV *SH, Type *Ty, bool Root);
-
-  /// Insert code to directly compute the specified SCEV expression into the
-  /// program. The code is inserted into the specified block. If \p
-  /// Root is true, this indicates that \p SH is the top-level expression to
-  /// expand passed from an external client call.
-  Value *expandCodeForImpl(const SCEV *SH, Type *Ty, Instruction *I, bool Root);
-
   /// Recursive helper function for isHighCostExpansion.
   bool isHighCostExpansionHelper(const SCEV *S, Loop *L, const Instruction &At,
                                  int &BudgetRemaining,
@@ -441,11 +419,6 @@ class SCEVExpander : public SCEVVisitor<SCEVExpander, Value *> {
                       Instruction *Pos, PHINode *LoopPhi);
 
   void fixupInsertPoints(Instruction *I);
-
-  /// If required, create LCSSA PHIs for \p Users' operand \p OpIdx. If new
-  /// LCSSA PHIs have been created, return the LCSSA PHI available at \p User.
-  /// If no PHIs have been created, return the unchanged operand \p OpIdx.
-  Value *fixupLCSSAFormFor(Instruction *User, unsigned OpIdx);
 };
 } // namespace llvm
 

diff  --git a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index c3e46c1fadef..cf02ef1e83f3 100644
--- a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -5514,8 +5514,8 @@ void LSRInstance::ImplementSolution(
   // we can remove them after we are done working.
   SmallVector<WeakTrackingVH, 16> DeadInsts;
 
-  SCEVExpander Rewriter(SE, L->getHeader()->getModule()->getDataLayout(), "lsr",
-                        false);
+  SCEVExpander Rewriter(SE, L->getHeader()->getModule()->getDataLayout(),
+                        "lsr");
 #ifndef NDEBUG
   Rewriter.setDebugType(DEBUG_TYPE);
 #endif
@@ -5780,7 +5780,7 @@ static bool ReduceLoopStrength(Loop *L, IVUsers &IU, ScalarEvolution &SE,
   if (EnablePhiElim && L->isLoopSimplifyForm()) {
     SmallVector<WeakTrackingVH, 16> DeadInsts;
     const DataLayout &DL = L->getHeader()->getModule()->getDataLayout();
-    SCEVExpander Rewriter(SE, DL, "lsr", false);
+    SCEVExpander Rewriter(SE, DL, "lsr");
 #ifndef NDEBUG
     Rewriter.setDebugType(DEBUG_TYPE);
 #endif

diff  --git a/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp b/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
index 1a10e580c68c..c99d612a7768 100644
--- a/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
+++ b/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
@@ -27,7 +27,6 @@
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
-#include "llvm/Transforms/Utils/LoopUtils.h"
 
 using namespace llvm;
 
@@ -462,10 +461,9 @@ Value *SCEVExpander::expandAddToGEP(const SCEV *const *op_begin,
     // we didn't find any operands that could be factored, tentatively
     // assume that element zero was selected (since the zero offset
     // would obviously be folded away).
-    Value *Scaled =
-        ScaledOps.empty()
-            ? Constant::getNullValue(Ty)
-            : expandCodeForImpl(SE.getAddExpr(ScaledOps), Ty, false);
+    Value *Scaled = ScaledOps.empty() ?
+                    Constant::getNullValue(Ty) :
+                    expandCodeFor(SE.getAddExpr(ScaledOps), Ty);
     GepIndices.push_back(Scaled);
 
     // Collect struct field index operands.
@@ -524,7 +522,7 @@ Value *SCEVExpander::expandAddToGEP(const SCEV *const *op_begin,
            SE.DT.dominates(cast<Instruction>(V), &*Builder.GetInsertPoint()));
 
     // Expand the operands for a plain byte offset.
-    Value *Idx = expandCodeForImpl(SE.getAddExpr(Ops), Ty, false);
+    Value *Idx = expandCodeFor(SE.getAddExpr(Ops), Ty);
 
     // Fold a GEP with constant operands.
     if (Constant *CLHS = dyn_cast<Constant>(V))
@@ -745,14 +743,14 @@ Value *SCEVExpander::visitAddExpr(const SCEVAddExpr *S) {
       Sum = expandAddToGEP(NewOps.begin(), NewOps.end(), PTy, Ty, expand(Op));
     } else if (Op->isNonConstantNegative()) {
       // Instead of doing a negate and add, just do a subtract.
-      Value *W = expandCodeForImpl(SE.getNegativeSCEV(Op), Ty, false);
+      Value *W = expandCodeFor(SE.getNegativeSCEV(Op), Ty);
       Sum = InsertNoopCastOfTo(Sum, Ty);
       Sum = InsertBinop(Instruction::Sub, Sum, W, SCEV::FlagAnyWrap,
                         /*IsSafeToHoist*/ true);
       ++I;
     } else {
       // A simple add.
-      Value *W = expandCodeForImpl(Op, Ty, false);
+      Value *W = expandCodeFor(Op, Ty);
       Sum = InsertNoopCastOfTo(Sum, Ty);
       // Canonicalize a constant to the RHS.
       if (isa<Constant>(Sum)) std::swap(Sum, W);
@@ -804,7 +802,7 @@ Value *SCEVExpander::visitMulExpr(const SCEVMulExpr *S) {
 
     // Calculate powers with exponents 1, 2, 4, 8 etc. and include those of them
     // that are needed into the result.
-    Value *P = expandCodeForImpl(I->second, Ty, false);
+    Value *P = expandCodeFor(I->second, Ty);
     Value *Result = nullptr;
     if (Exponent & 1)
       Result = P;
@@ -863,7 +861,7 @@ Value *SCEVExpander::visitMulExpr(const SCEVMulExpr *S) {
 Value *SCEVExpander::visitUDivExpr(const SCEVUDivExpr *S) {
   Type *Ty = SE.getEffectiveSCEVType(S->getType());
 
-  Value *LHS = expandCodeForImpl(S->getLHS(), Ty, false);
+  Value *LHS = expandCodeFor(S->getLHS(), Ty);
   if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(S->getRHS())) {
     const APInt &RHS = SC->getAPInt();
     if (RHS.isPowerOf2())
@@ -872,7 +870,7 @@ Value *SCEVExpander::visitUDivExpr(const SCEVUDivExpr *S) {
                          SCEV::FlagAnyWrap, /*IsSafeToHoist*/ true);
   }
 
-  Value *RHS = expandCodeForImpl(S->getRHS(), Ty, false);
+  Value *RHS = expandCodeFor(S->getRHS(), Ty);
   return InsertBinop(Instruction::UDiv, LHS, RHS, SCEV::FlagAnyWrap,
                      /*IsSafeToHoist*/ SE.isKnownNonZero(S->getRHS()));
 }
@@ -1267,9 +1265,8 @@ SCEVExpander::getAddRecExprPHILiterally(const SCEVAddRecExpr *Normalized,
   // Expand code for the start value into the loop preheader.
   assert(L->getLoopPreheader() &&
          "Can't expand add recurrences without a loop preheader!");
-  Value *StartV =
-      expandCodeForImpl(Normalized->getStart(), ExpandTy,
-                        L->getLoopPreheader()->getTerminator(), false);
+  Value *StartV = expandCodeFor(Normalized->getStart(), ExpandTy,
+                                L->getLoopPreheader()->getTerminator());
 
   // StartV must have been be inserted into L's preheader to dominate the new
   // phi.
@@ -1287,8 +1284,8 @@ SCEVExpander::getAddRecExprPHILiterally(const SCEVAddRecExpr *Normalized,
   if (useSubtract)
     Step = SE.getNegativeSCEV(Step);
   // Expand the step somewhere that dominates the loop header.
-  Value *StepV = expandCodeForImpl(
-      Step, IntTy, &*L->getHeader()->getFirstInsertionPt(), false);
+  Value *StepV = expandCodeFor(Step, IntTy,
+                               &*L->getHeader()->getFirstInsertionPt());
 
   // The no-wrap behavior proved by IsIncrement(NUW|NSW) is only applicable if
   // we actually do emit an addition.  It does not apply if we emit a
@@ -1433,8 +1430,8 @@ Value *SCEVExpander::expandAddRecExprLiterally(const SCEVAddRecExpr *S) {
       {
         // Expand the step somewhere that dominates the loop header.
         SCEVInsertPointGuard Guard(Builder, this);
-        StepV = expandCodeForImpl(
-            Step, IntTy, &*L->getHeader()->getFirstInsertionPt(), false);
+        StepV = expandCodeFor(Step, IntTy,
+                              &*L->getHeader()->getFirstInsertionPt());
       }
       Result = expandIVInc(PN, StepV, L, ExpandTy, IntTy, useSubtract);
     }
@@ -1453,8 +1450,8 @@ Value *SCEVExpander::expandAddRecExprLiterally(const SCEVAddRecExpr *S) {
 
     // Invert the result.
     if (InvertStep)
-      Result = Builder.CreateSub(
-          expandCodeForImpl(Normalized->getStart(), TruncTy, false), Result);
+      Result = Builder.CreateSub(expandCodeFor(Normalized->getStart(), TruncTy),
+                                 Result);
   }
 
   // Re-apply any non-loop-dominating scale.
@@ -1462,22 +1459,22 @@ Value *SCEVExpander::expandAddRecExprLiterally(const SCEVAddRecExpr *S) {
     assert(S->isAffine() && "Can't linearly scale non-affine recurrences.");
     Result = InsertNoopCastOfTo(Result, IntTy);
     Result = Builder.CreateMul(Result,
-                               expandCodeForImpl(PostLoopScale, IntTy, false));
+                               expandCodeFor(PostLoopScale, IntTy));
   }
 
   // Re-apply any non-loop-dominating offset.
   if (PostLoopOffset) {
     if (PointerType *PTy = dyn_cast<PointerType>(ExpandTy)) {
       if (Result->getType()->isIntegerTy()) {
-        Value *Base = expandCodeForImpl(PostLoopOffset, ExpandTy, false);
+        Value *Base = expandCodeFor(PostLoopOffset, ExpandTy);
         Result = expandAddToGEP(SE.getUnknown(Result), PTy, IntTy, Base);
       } else {
         Result = expandAddToGEP(PostLoopOffset, PTy, IntTy, Result);
       }
     } else {
       Result = InsertNoopCastOfTo(Result, IntTy);
-      Result = Builder.CreateAdd(
-          Result, expandCodeForImpl(PostLoopOffset, IntTy, false));
+      Result = Builder.CreateAdd(Result,
+                                 expandCodeFor(PostLoopOffset, IntTy));
     }
   }
 
@@ -1519,8 +1516,8 @@ Value *SCEVExpander::visitAddRecExpr(const SCEVAddRecExpr *S) {
                                        S->getNoWrapFlags(SCEV::FlagNW)));
     BasicBlock::iterator NewInsertPt =
         findInsertPointAfter(cast<Instruction>(V), Builder.GetInsertBlock());
-    V = expandCodeForImpl(SE.getTruncateExpr(SE.getUnknown(V), Ty), nullptr,
-                          &*NewInsertPt, false);
+    V = expandCodeFor(SE.getTruncateExpr(SE.getUnknown(V), Ty), nullptr,
+                      &*NewInsertPt);
     return V;
   }
 
@@ -1635,25 +1632,22 @@ Value *SCEVExpander::visitAddRecExpr(const SCEVAddRecExpr *S) {
 
 Value *SCEVExpander::visitTruncateExpr(const SCEVTruncateExpr *S) {
   Type *Ty = SE.getEffectiveSCEVType(S->getType());
-  Value *V = expandCodeForImpl(
-      S->getOperand(), SE.getEffectiveSCEVType(S->getOperand()->getType()),
-      false);
+  Value *V = expandCodeFor(S->getOperand(),
+                           SE.getEffectiveSCEVType(S->getOperand()->getType()));
   return Builder.CreateTrunc(V, Ty);
 }
 
 Value *SCEVExpander::visitZeroExtendExpr(const SCEVZeroExtendExpr *S) {
   Type *Ty = SE.getEffectiveSCEVType(S->getType());
-  Value *V = expandCodeForImpl(
-      S->getOperand(), SE.getEffectiveSCEVType(S->getOperand()->getType()),
-      false);
+  Value *V = expandCodeFor(S->getOperand(),
+                           SE.getEffectiveSCEVType(S->getOperand()->getType()));
   return Builder.CreateZExt(V, Ty);
 }
 
 Value *SCEVExpander::visitSignExtendExpr(const SCEVSignExtendExpr *S) {
   Type *Ty = SE.getEffectiveSCEVType(S->getType());
-  Value *V = expandCodeForImpl(
-      S->getOperand(), SE.getEffectiveSCEVType(S->getOperand()->getType()),
-      false);
+  Value *V = expandCodeFor(S->getOperand(),
+                           SE.getEffectiveSCEVType(S->getOperand()->getType()));
   return Builder.CreateSExt(V, Ty);
 }
 
@@ -1668,7 +1662,7 @@ Value *SCEVExpander::visitSMaxExpr(const SCEVSMaxExpr *S) {
       Ty = SE.getEffectiveSCEVType(Ty);
       LHS = InsertNoopCastOfTo(LHS, Ty);
     }
-    Value *RHS = expandCodeForImpl(S->getOperand(i), Ty, false);
+    Value *RHS = expandCodeFor(S->getOperand(i), Ty);
     Value *ICmp = Builder.CreateICmpSGT(LHS, RHS);
     Value *Sel = Builder.CreateSelect(ICmp, LHS, RHS, "smax");
     LHS = Sel;
@@ -1691,7 +1685,7 @@ Value *SCEVExpander::visitUMaxExpr(const SCEVUMaxExpr *S) {
       Ty = SE.getEffectiveSCEVType(Ty);
       LHS = InsertNoopCastOfTo(LHS, Ty);
     }
-    Value *RHS = expandCodeForImpl(S->getOperand(i), Ty, false);
+    Value *RHS = expandCodeFor(S->getOperand(i), Ty);
     Value *ICmp = Builder.CreateICmpUGT(LHS, RHS);
     Value *Sel = Builder.CreateSelect(ICmp, LHS, RHS, "umax");
     LHS = Sel;
@@ -1714,7 +1708,7 @@ Value *SCEVExpander::visitSMinExpr(const SCEVSMinExpr *S) {
       Ty = SE.getEffectiveSCEVType(Ty);
       LHS = InsertNoopCastOfTo(LHS, Ty);
     }
-    Value *RHS = expandCodeForImpl(S->getOperand(i), Ty, false);
+    Value *RHS = expandCodeFor(S->getOperand(i), Ty);
     Value *ICmp = Builder.CreateICmpSLT(LHS, RHS);
     Value *Sel = Builder.CreateSelect(ICmp, LHS, RHS, "smin");
     LHS = Sel;
@@ -1737,7 +1731,7 @@ Value *SCEVExpander::visitUMinExpr(const SCEVUMinExpr *S) {
       Ty = SE.getEffectiveSCEVType(Ty);
       LHS = InsertNoopCastOfTo(LHS, Ty);
     }
-    Value *RHS = expandCodeForImpl(S->getOperand(i), Ty, false);
+    Value *RHS = expandCodeFor(S->getOperand(i), Ty);
     Value *ICmp = Builder.CreateICmpULT(LHS, RHS);
     Value *Sel = Builder.CreateSelect(ICmp, LHS, RHS, "umin");
     LHS = Sel;
@@ -1749,43 +1743,15 @@ Value *SCEVExpander::visitUMinExpr(const SCEVUMinExpr *S) {
   return LHS;
 }
 
-Value *SCEVExpander::expandCodeForImpl(const SCEV *SH, Type *Ty,
-                                       Instruction *IP, bool Root) {
+Value *SCEVExpander::expandCodeFor(const SCEV *SH, Type *Ty,
+                                   Instruction *IP) {
   setInsertPoint(IP);
-  Value *V = expandCodeForImpl(SH, Ty, Root);
-  return V;
+  return expandCodeFor(SH, Ty);
 }
 
-Value *SCEVExpander::expandCodeForImpl(const SCEV *SH, Type *Ty, bool Root) {
+Value *SCEVExpander::expandCodeFor(const SCEV *SH, Type *Ty) {
   // Expand the code for this SCEV.
   Value *V = expand(SH);
-
-  if (PreserveLCSSA) {
-    if (auto *Inst = dyn_cast<Instruction>(V)) {
-      // Create a temporary instruction to at the current insertion point, so we
-      // can hand it off to the helper to create LCSSA PHIs if required for the
-      // new use.
-      // FIXME: Ideally formLCSSAForInstructions (used in fixupLCSSAFormFor)
-      // would accept a insertion point and return an LCSSA phi for that
-      // insertion point, so there is no need to insert & remove the temporary
-      // instruction.
-      Instruction *Tmp;
-      if (Inst->getType()->isIntegerTy())
-        Tmp = cast<Instruction>(Builder.CreateAdd(Inst, Inst));
-      else {
-        assert(Inst->getType()->isPointerTy());
-        Tmp = cast<Instruction>(Builder.CreateGEP(Inst, Builder.getInt32(1)));
-      }
-      V = fixupLCSSAFormFor(Tmp, 0);
-
-      // Clean up temporary instruction.
-      InsertedValues.erase(Tmp);
-      InsertedPostIncValues.erase(Tmp);
-      Tmp->eraseFromParent();
-    }
-  }
-
-  InsertedExpressions[std::make_pair(SH, &*Builder.GetInsertPoint())] = V;
   if (Ty) {
     assert(SE.getTypeSizeInBits(Ty) == SE.getTypeSizeInBits(SH->getType()) &&
            "non-trivial casts should be done with the SCEVs directly!");
@@ -1925,28 +1891,10 @@ Value *SCEVExpander::expand(const SCEV *S) {
 }
 
 void SCEVExpander::rememberInstruction(Value *I) {
-  auto DoInsert = [this](Value *V) {
-    if (!PostIncLoops.empty())
-      InsertedPostIncValues.insert(V);
-    else
-      InsertedValues.insert(V);
-  };
-  DoInsert(I);
-
-  if (!PreserveLCSSA)
-    return;
-
-  if (auto *Inst = dyn_cast<Instruction>(I)) {
-    // A new instruction has been added, which might introduce new uses outside
-    // a defining loop. Fix LCSSA from for each operand of the new instruction,
-    // if required.
-    for (unsigned OpIdx = 0, OpEnd = Inst->getNumOperands(); OpIdx != OpEnd;
-         OpIdx++) {
-      auto *V = fixupLCSSAFormFor(Inst, OpIdx);
-      if (V != I)
-        DoInsert(V);
-    }
-  }
+  if (!PostIncLoops.empty())
+    InsertedPostIncValues.insert(I);
+  else
+    InsertedValues.insert(I);
 }
 
 /// getOrInsertCanonicalInductionVariable - This method returns the
@@ -1965,8 +1913,9 @@ SCEVExpander::getOrInsertCanonicalInductionVariable(const Loop *L,
 
   // Emit code for it.
   SCEVInsertPointGuard Guard(Builder, this);
-  PHINode *V = cast<PHINode>(expandCodeForImpl(
-      H, nullptr, &*L->getHeader()->getFirstInsertionPt(), false));
+  PHINode *V =
+      cast<PHINode>(expandCodeFor(H, nullptr,
+                                  &*L->getHeader()->getFirstInsertionPt()));
 
   return V;
 }
@@ -2366,10 +2315,8 @@ Value *SCEVExpander::expandCodeForPredicate(const SCEVPredicate *Pred,
 
 Value *SCEVExpander::expandEqualPredicate(const SCEVEqualPredicate *Pred,
                                           Instruction *IP) {
-  Value *Expr0 =
-      expandCodeForImpl(Pred->getLHS(), Pred->getLHS()->getType(), IP, false);
-  Value *Expr1 =
-      expandCodeForImpl(Pred->getRHS(), Pred->getRHS()->getType(), IP, false);
+  Value *Expr0 = expandCodeFor(Pred->getLHS(), Pred->getLHS()->getType(), IP);
+  Value *Expr1 = expandCodeFor(Pred->getRHS(), Pred->getRHS()->getType(), IP);
 
   Builder.SetInsertPoint(IP);
   auto *I = Builder.CreateICmpNE(Expr0, Expr1, "ident.check");
@@ -2401,16 +2348,15 @@ Value *SCEVExpander::generateOverflowCheck(const SCEVAddRecExpr *AR,
 
   IntegerType *CountTy = IntegerType::get(Loc->getContext(), SrcBits);
   Builder.SetInsertPoint(Loc);
-  Value *TripCountVal = expandCodeForImpl(ExitCount, CountTy, Loc, false);
+  Value *TripCountVal = expandCodeFor(ExitCount, CountTy, Loc);
 
   IntegerType *Ty =
       IntegerType::get(Loc->getContext(), SE.getTypeSizeInBits(ARTy));
   Type *ARExpandTy = DL.isNonIntegralPointerType(ARTy) ? ARTy : Ty;
 
-  Value *StepValue = expandCodeForImpl(Step, Ty, Loc, false);
-  Value *NegStepValue =
-      expandCodeForImpl(SE.getNegativeSCEV(Step), Ty, Loc, false);
-  Value *StartValue = expandCodeForImpl(Start, ARExpandTy, Loc, false);
+  Value *StepValue = expandCodeFor(Step, Ty, Loc);
+  Value *NegStepValue = expandCodeFor(SE.getNegativeSCEV(Step), Ty, Loc);
+  Value *StartValue = expandCodeFor(Start, ARExpandTy, Loc);
 
   ConstantInt *Zero =
       ConstantInt::get(Loc->getContext(), APInt::getNullValue(DstBits));
@@ -2513,25 +2459,6 @@ Value *SCEVExpander::expandUnionPredicate(const SCEVUnionPredicate *Union,
   return Check;
 }
 
-Value *SCEVExpander::fixupLCSSAFormFor(Instruction *User, unsigned OpIdx) {
-  assert(PreserveLCSSA);
-  SmallVector<Instruction *, 1> ToUpdate;
-
-  auto *OpV = User->getOperand(OpIdx);
-  auto *OpI = dyn_cast<Instruction>(OpV);
-  if (!OpI)
-    return OpV;
-
-  Loop *DefLoop = SE.LI.getLoopFor(OpI->getParent());
-  Loop *UseLoop = SE.LI.getLoopFor(User->getParent());
-  if (!DefLoop || UseLoop == DefLoop || DefLoop->contains(UseLoop))
-    return OpV;
-
-  ToUpdate.push_back(OpI);
-  formLCSSAForInstructions(ToUpdate, SE.DT, SE.LI, &SE);
-  return User->getOperand(OpIdx);
-}
-
 namespace {
 // Search for a SCEV subexpression that is not safe to expand.  Any expression
 // that may expand to a !isSafeToSpeculativelyExecute value is unsafe, namely

diff  --git a/llvm/unittests/Transforms/Utils/ScalarEvolutionExpanderTest.cpp b/llvm/unittests/Transforms/Utils/ScalarEvolutionExpanderTest.cpp
index 6e83370dfeb9..c146d155ffbe 100644
--- a/llvm/unittests/Transforms/Utils/ScalarEvolutionExpanderTest.cpp
+++ b/llvm/unittests/Transforms/Utils/ScalarEvolutionExpanderTest.cpp
@@ -265,7 +265,7 @@ TEST_F(ScalarEvolutionExpanderTest, SCEVExpanderIsSafeToExpandAt) {
   Phi->addIncoming(Add, L);
 
   Builder.SetInsertPoint(Post);
-  Instruction *Ret = Builder.CreateRetVoid();
+  Builder.CreateRetVoid();
 
   ScalarEvolution SE = buildSE(*F);
   const SCEV *S = SE.getSCEV(Phi);
@@ -276,11 +276,6 @@ TEST_F(ScalarEvolutionExpanderTest, SCEVExpanderIsSafeToExpandAt) {
   EXPECT_FALSE(isSafeToExpandAt(AR, LPh->getTerminator(), SE));
   EXPECT_TRUE(isSafeToExpandAt(AR, L->getTerminator(), SE));
   EXPECT_TRUE(isSafeToExpandAt(AR, Post->getTerminator(), SE));
-
-  EXPECT_TRUE(LI->getLoopFor(L)->isLCSSAForm(*DT));
-  SCEVExpander Exp(SE, M.getDataLayout(), "expander");
-  Exp.expandCodeFor(SE.getSCEV(Add), nullptr, Ret);
-  EXPECT_TRUE(LI->getLoopFor(L)->isLCSSAForm(*DT));
 }
 
 // Check that SCEV expander does not use the nuw instruction


        


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