Revert r26084: Enable loopreroll for sext of loop control only IV

llvm-svn: 269119

llvm/lib/Transforms/Scalar/LoopRerollPass.cpp

@@ -512,11 +512,11 @@ static const SCEVConstant *getIncrmentFactorSCEV(ScalarEvolution *SE,
 
 // Check if an IV is only used to control the loop. There are two cases:
 // 1. It only has one use which is loop increment, and the increment is only
-// used by comparison and the PHI (could has sext with nsw in between), and the
+// used by comparison and the PHI, and the comparison is only used by branch.
-// comparison is only used by branch.
 // 2. It is used by loop increment and the comparison, the loop increment is
 // only used by the PHI, and the comparison is used only by the branch.
 bool LoopReroll::isLoopControlIV(Loop *L, Instruction *IV) {
+
   unsigned IVUses = IV->getNumUses();
   if (IVUses != 2 && IVUses != 1)
     return false;
@@ -551,17 +551,9 @@ bool LoopReroll::isLoopControlIV(Loop *L, Instruction *IV) {
             if (PN != IV)
               return false;
           }
-          // Must be a CMP or an ext (of a value with nsw) then CMP
+          // Must be a CMP
-          else {
+          else if (!isCompareUsedByBranch(dyn_cast<Instruction>(UU)))
-            Instruction *UUser = dyn_cast<Instruction>(UU);
+            return false;
-            // Skip SExt if we are extending an nsw value
-            // TODO: Allow ZExt too
-            if (BO->hasNoSignedWrap() && UUser && UUser->getNumUses() == 1 &&
-                isa<SExtInst>(UUser))
-              UUser = dyn_cast<Instruction>(*(UUser->user_begin()));
-            if (!isCompareUsedByBranch(UUser))
-              return false;
-          }
         }
       } else
         return false;
@@ -1169,11 +1161,6 @@ bool LoopReroll::DAGRootTracker::validate(ReductionTracker &Reductions) {
         Instruction *UUser = dyn_cast<Instruction>(UU);
         // UUser could be compare, PHI or branch
         Uses[UUser].set(IL_All);
-        // Skip SExt
-        if (isa<SExtInst>(UUser)) {
-          UUser = dyn_cast<Instruction>(*(UUser->user_begin()));
-          Uses[UUser].set(IL_All);
-        }
         // Is UUser a compare instruction?
         if (UU->hasOneUse()) {
           Instruction *BI = dyn_cast<BranchInst>(*UUser->user_begin());
@@ -1515,6 +1502,8 @@ void LoopReroll::DAGRootTracker::replaceIV(Instruction *Inst,
         if (NeedNewIV)
           ICSCEV = SE->getMulExpr(IterCount,
                                   SE->getConstant(IterCount->getType(), Scale));
+        else
+          ICSCEV = RealIVSCEV->evaluateAtIteration(IterCount, *SE);
 
         // Iteration count SCEV minus or plus 1
         const SCEV *MinusPlus1SCEV =
@@ -1526,26 +1515,18 @@ void LoopReroll::DAGRootTracker::replaceIV(Instruction *Inst,
 
         const SCEV *ICMinusPlus1SCEV = SE->getMinusSCEV(ICSCEV, MinusPlus1SCEV);
         // Iteration count minus 1
-        Instruction *InsertPtr = nullptr;
+        Value *ICMinusPlus1 = nullptr;
         if (isa<SCEVConstant>(ICMinusPlus1SCEV)) {
-          InsertPtr = BI;
+          ICMinusPlus1 =
+              Expander.expandCodeFor(ICMinusPlus1SCEV, NewIV->getType(), BI);
         } else {
           BasicBlock *Preheader = L->getLoopPreheader();
           if (!Preheader)
             Preheader = InsertPreheaderForLoop(L, DT, LI, PreserveLCSSA);
-          InsertPtr = Preheader->getTerminator();
+          ICMinusPlus1 = Expander.expandCodeFor(
+              ICMinusPlus1SCEV, NewIV->getType(), Preheader->getTerminator());
         }
 
-        if (!isa<PointerType>(NewIV->getType()) && NeedNewIV &&
-            (SE->getTypeSizeInBits(NewIV->getType()) <
-             SE->getTypeSizeInBits(ICMinusPlus1SCEV->getType()))) {
-          IRBuilder<> Builder(BI);
-          Builder.SetCurrentDebugLocation(BI->getDebugLoc());
-          NewIV = Builder.CreateSExt(NewIV, ICMinusPlus1SCEV->getType());
-        }
-        Value *ICMinusPlus1 = Expander.expandCodeFor(
-            ICMinusPlus1SCEV, NewIV->getType(), InsertPtr);
-
         Value *Cond =
             new ICmpInst(BI, CmpInst::ICMP_EQ, NewIV, ICMinusPlus1, "exitcond");
         BI->setCondition(Cond);
@@ -1724,7 +1705,6 @@ bool LoopReroll::runOnLoop(Loop *L, LPPassManager &LPM) {
 
   const SCEV *LIBETC = SE->getBackedgeTakenCount(L);
   const SCEV *IterCount = SE->getAddExpr(LIBETC, SE->getOne(LIBETC->getType()));
-  DEBUG(dbgs() << "\n Before Reroll:\n" << *(L->getHeader()) << "\n");
   DEBUG(dbgs() << "LRR: iteration count = " << *IterCount << "\n");
 
   // First, we need to find the induction variable with respect to which we can
@@ -1751,7 +1731,6 @@ bool LoopReroll::runOnLoop(Loop *L, LPPassManager &LPM) {
       Changed = true;
       break;
     }
-  DEBUG(dbgs() << "\n After Reroll:\n" << *(L->getHeader()) << "\n");
 
   // Trip count of L has changed so SE must be re-evaluated.
   if (Changed)

llvm/test/Transforms/LoopReroll/indvar_with_ext.ll

@@ -1,186 +0,0 @@
-; RUN: opt -S  -loop-reroll   %s | FileCheck %s
-target triple = "aarch64--linux-gnu"
-
-define void @test(i32 %n, float* %arrayidx200, float* %arrayidx164, float* %arrayidx172) {
-entry:
-  %rem.i = srem i32 %n, 4
-  %t22 = load float, float* %arrayidx172, align 4
-  %cmp.9 = icmp eq i32 %n, 0
-  %t7 = sext i32 %n to i64
-  br i1 %cmp.9, label %while.end, label %while.body.preheader
-
-while.body.preheader:
-  br label %while.body
-
-while.body:
-;CHECK-LABEL: while.body:
-;CHECK-NEXT:    %indvars.iv.i423 = phi i64 [ %indvars.iv.next.i424, %while.body ], [ 0, %while.body.preheader ]
-;CHECK-NEXT:    [[T1:%[0-9]+]] = trunc i64 %indvars.iv.i423 to i32
-;CHECK-NEXT:    %arrayidx62.i = getelementptr inbounds float, float* %arrayidx200, i64 %indvars.iv.i423
-;CHECK-NEXT:    %t1 = load float, float* %arrayidx62.i, align 4
-;CHECK-NEXT:    %arrayidx64.i = getelementptr inbounds float, float* %arrayidx164, i64 %indvars.iv.i423
-;CHECK-NEXT:    %t2 = load float, float* %arrayidx64.i, align 4
-;CHECK-NEXT:    %mul65.i = fmul fast float %t2, %t22
-;CHECK-NEXT:    %add66.i = fadd fast float %mul65.i, %t1
-;CHECK-NEXT:    store float %add66.i, float* %arrayidx62.i, align 4
-;CHECK-NEXT:    %indvars.iv.next.i424 = add i64 %indvars.iv.i423, 1
-;CHECK-NEXT:    [[T2:%[0-9]+]] = sext i32 [[T1]] to i64
-;CHECK-NEXT:    %exitcond = icmp eq i64 [[T2]], %{{[0-9]+}}
-;CHECK-NEXT:    br i1 %exitcond, label %while.end.loopexit, label %while.body
-
-  %indvars.iv.i423 = phi i64 [ %indvars.iv.next.i424, %while.body ], [ 0, %while.body.preheader ]
-  %i.22.i = phi i32 [ %add103.i, %while.body ], [ %rem.i, %while.body.preheader ]
-  %arrayidx62.i = getelementptr inbounds float, float* %arrayidx200, i64 %indvars.iv.i423
-  %t1 = load float, float* %arrayidx62.i, align 4
-  %arrayidx64.i = getelementptr inbounds float, float* %arrayidx164, i64 %indvars.iv.i423
-  %t2 = load float, float* %arrayidx64.i, align 4
-  %mul65.i = fmul fast float %t2, %t22
-  %add66.i = fadd fast float %mul65.i, %t1
-  store float %add66.i, float* %arrayidx62.i, align 4
-  %t3 = add nsw i64 %indvars.iv.i423, 1
-  %arrayidx71.i = getelementptr inbounds float, float* %arrayidx200, i64 %t3
-  %t4 = load float, float* %arrayidx71.i, align 4
-  %arrayidx74.i = getelementptr inbounds float, float* %arrayidx164, i64 %t3
-  %t5 = load float, float* %arrayidx74.i, align 4
-  %mul75.i = fmul fast float %t5, %t22
-  %add76.i = fadd fast float %mul75.i, %t4
-  store float %add76.i, float* %arrayidx71.i, align 4
-  %add103.i = add nsw i32 %i.22.i, 2
-  %t6 = sext i32 %add103.i to i64
-  %cmp58.i = icmp slt i64 %t6, %t7
-  %indvars.iv.next.i424 = add i64 %indvars.iv.i423, 2
-  br i1 %cmp58.i, label %while.body, label %while.end.loopexit
-
-while.end.loopexit:
-  br label %while.end
-
-while.end:
-  ret void
-}
-
-; Function Attrs: noinline norecurse nounwind
-define i32 @test2(i64 %n, i32* nocapture %x, i32* nocapture readonly %y) {
-entry:
-  %cmp18 = icmp sgt i64 %n, 0
-  br i1 %cmp18, label %for.body.preheader, label %for.end
-
-for.body.preheader:                               ; preds = %entry
-  br label %for.body
-
-for.body:                                         ; preds = %for.body.preheader, %for.body
-
-;CHECK:     for.body:
-;CHECK-NEXT:  %indvar = phi i64 [ %indvar.next, %for.body ], [ 0, %for.body.preheader ]
-;CHECK-NEXT:  %arrayidx = getelementptr inbounds i32, i32* %y, i64 %indvar
-;CHECK-NEXT:  [[T1:%[0-9]+]] = load i32, i32* %arrayidx, align 4
-;CHECK-NEXT:  %arrayidx3 = getelementptr inbounds i32, i32* %x, i64 %indvar
-;CHECK-NEXT:  store i32 [[T1]], i32* %arrayidx3, align 4
-;CHECK-NEXT:  %indvar.next = add i64 %indvar, 1
-;CHECK-NEXT:  %exitcond = icmp eq i64 %indvar, %{{[0-9]+}}
-;CHECK-NEXT:  br i1 %exitcond, label %for.end.loopexit, label %for.body
-
-  %indvars.iv = phi i64 [ %indvars.iv.next, %for.body ], [ 0, %for.body.preheader ]
-  %arrayidx = getelementptr inbounds i32, i32* %y, i64 %indvars.iv
-  %0 = load i32, i32* %arrayidx, align 4
-  %arrayidx3 = getelementptr inbounds i32, i32* %x, i64 %indvars.iv
-  store i32 %0, i32* %arrayidx3, align 4
-  %1 = or i64 %indvars.iv, 1
-  %arrayidx5 = getelementptr inbounds i32, i32* %y, i64 %1
-  %2 = load i32, i32* %arrayidx5, align 4
-  %arrayidx8 = getelementptr inbounds i32, i32* %x, i64 %1
-  store i32 %2, i32* %arrayidx8, align 4
-  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 2
-  %cmp = icmp slt i64 %indvars.iv.next, %n
-  br i1 %cmp, label %for.body, label %for.end.loopexit
-
-for.end.loopexit:                                 ; preds = %for.body
-  br label %for.end
-
-for.end:                                          ; preds = %for.end.loopexit, %entry
-  ret i32 0
-}
-
-; Function Attrs: noinline norecurse nounwind
-define i32 @test3(i32 %n, i32* nocapture %x, i32* nocapture readonly %y) {
-entry:
-  %cmp21 = icmp sgt i32 %n, 0
-  br i1 %cmp21, label %for.body.preheader, label %for.end
-
-for.body.preheader:                               ; preds = %entry
-  br label %for.body
-
-for.body:                                         ; preds = %for.body.preheader, %for.body
-
-;CHECK:      for.body:
-;CHECK:        %add12 = add i8 %i.022, 2
-;CHECK-NEXT:   %conv = sext i8 %add12 to i32
-;CHECK-NEXT:   %cmp = icmp slt i32 %conv, %n
-;CHECK-NEXT:   br i1 %cmp, label %for.body, label %for.end.loopexit
-
-  %conv23 = phi i32 [ %conv, %for.body ], [ 0, %for.body.preheader ]
-  %i.022 = phi i8 [ %add12, %for.body ], [ 0, %for.body.preheader ]
-  %idxprom = sext i8 %i.022 to i64
-  %arrayidx = getelementptr inbounds i32, i32* %y, i64 %idxprom
-  %0 = load i32, i32* %arrayidx, align 4
-  %arrayidx3 = getelementptr inbounds i32, i32* %x, i64 %idxprom
-  store i32 %0, i32* %arrayidx3, align 4
-  %add = or i32 %conv23, 1
-  %idxprom5 = sext i32 %add to i64
-  %arrayidx6 = getelementptr inbounds i32, i32* %y, i64 %idxprom5
-  %1 = load i32, i32* %arrayidx6, align 4
-  %arrayidx10 = getelementptr inbounds i32, i32* %x, i64 %idxprom5
-  store i32 %1, i32* %arrayidx10, align 4
-  %add12 = add i8 %i.022, 2
-  %conv = sext i8 %add12 to i32
-  %cmp = icmp slt i32 %conv, %n
-  br i1 %cmp, label %for.body, label %for.end.loopexit
-
-for.end.loopexit:                                 ; preds = %for.body
-  br label %for.end
-
-for.end:                                          ; preds = %for.end.loopexit, %entry
-  ret i32 0
-}
-
-; Function Attrs: noinline norecurse nounwind
-define i32 @test4(i64 %n, i32* nocapture %x, i32* nocapture readonly %y) {
-entry:
-  %cmp18 = icmp eq i64 %n, 0
-  br i1 %cmp18, label %for.end, label %for.body.preheader
-
-for.body.preheader:                               ; preds = %entry
-  br label %for.body
-
-for.body:                                         ; preds = %for.body.preheader, %for.body
-
-;CHECK:     for.body:
-;CHECK-NEXT:  %indvar = phi i64 [ %indvar.next, %for.body ], [ 0, %for.body.preheader ]
-;CHECK-NEXT:  %arrayidx = getelementptr inbounds i32, i32* %y, i64 %indvar
-;CHECK-NEXT:  [[T1:%[0-9]+]] = load i32, i32* %arrayidx, align 4
-;CHECK-NEXT:  %arrayidx3 = getelementptr inbounds i32, i32* %x, i64 %indvar
-;CHECK-NEXT:  store i32 [[T1]], i32* %arrayidx3, align 4
-;CHECK-NEXT:  %indvar.next = add i64 %indvar, 1
-;CHECK-NEXT:  %exitcond = icmp eq i64 %indvar, %{{[0-9]+}}
-;CHECK-NEXT:  br i1 %exitcond, label %for.end.loopexit, label %for.body
-
-  %indvars.iv = phi i64 [ %indvars.iv.next, %for.body ], [ 0, %for.body.preheader ]
-  %arrayidx = getelementptr inbounds i32, i32* %y, i64 %indvars.iv
-  %0 = load i32, i32* %arrayidx, align 4
-  %arrayidx3 = getelementptr inbounds i32, i32* %x, i64 %indvars.iv
-  store i32 %0, i32* %arrayidx3, align 4
-  %1 = or i64 %indvars.iv, 1
-  %arrayidx5 = getelementptr inbounds i32, i32* %y, i64 %1
-  %2 = load i32, i32* %arrayidx5, align 4
-  %arrayidx8 = getelementptr inbounds i32, i32* %x, i64 %1
-  store i32 %2, i32* %arrayidx8, align 4
-  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 2
-  %cmp = icmp ult i64 %indvars.iv.next, %n
-  br i1 %cmp, label %for.body, label %for.end.loopexit
-
-for.end.loopexit:                                 ; preds = %for.body
-  br label %for.end
-
-for.end:                                          ; preds = %for.end.loopexit, %entry
-  ret i32 0
-}
-