Commit b6a86811 authored by Pawel Wodnicki's avatar Pawel Wodnicki
Browse files

Merging r168921: into the 3.2 release branch. 

Follow up to 168711: It's safe to base this analysis on the found compare, just return the value for the right predicate.

Thanks to Andy for catching this.

llvm-svn: 168974
parent 2a75f425

llvm/lib/Analysis/ScalarEvolution.cpp

+3 −4
Original line number Diff line number Diff line
@@ -6149,10 +6149,9 @@ bool ScalarEvolution::isImpliedCond(ICmpInst::Predicate Pred, 
  if (SimplifyICmpOperands(Pred, LHS, RHS))

    if (LHS == RHS)

      return CmpInst::isTrueWhenEqual(Pred);



  // Canonicalize the found cond too.  We can't conclude a result from the

  // simplified values.

  SimplifyICmpOperands(FoundPred, FoundLHS, FoundRHS);

  if (SimplifyICmpOperands(FoundPred, FoundLHS, FoundRHS))

    if (FoundLHS == FoundRHS)

      return CmpInst::isFalseWhenEqual(FoundPred);



  // Check to see if we can make the LHS or RHS match.

  if (LHS == FoundRHS || RHS == FoundLHS) {

llvm/test/Transforms/IndVarSimplify/eliminate-comparison.ll

+49 −0
Original line number Diff line number Diff line
@@ -160,3 +160,52 @@ unrolledend: ; preds = %forcond38 
}



declare void @llvm.trap() noreturn nounwind



; In this case the second loop only has a single iteration, fold the header away

; CHECK: @func_12

; CHECK: %tmp5 = icmp slt i32 %__key6.0, 10

; CHECK: br i1 true, label %noassert68, label %unrolledend

define i32 @func_12() nounwind uwtable {

entry:

  br label %forcond



forcond:                                          ; preds = %noassert, %entry

  %__key6.0 = phi i32 [ 2, %entry ], [ %tmp37, %noassert ]

  %tmp5 = icmp slt i32 %__key6.0, 10

  br i1 %tmp5, label %noassert, label %forcond38.preheader



forcond38.preheader:                              ; preds = %forcond

  br label %forcond38



noassert:                                         ; preds = %forbody

  %tmp13 = sdiv i32 -32768, %__key6.0

  %tmp2936 = shl i32 %tmp13, 24

  %sext23 = shl i32 %tmp13, 24

  %tmp32 = icmp eq i32 %tmp2936, %sext23

  %tmp37 = add i32 %__key6.0, 1

  br i1 %tmp32, label %forcond, label %assert33



assert33:                                         ; preds = %noassert

  tail call void @llvm.trap()

  unreachable



forcond38:                                        ; preds = %noassert68, %forcond38.preheader

  %__key8.0 = phi i32 [ %tmp81, %noassert68 ], [ 2, %forcond38.preheader ]

  %tmp46 = icmp slt i32 %__key8.0, 10

  br i1 %tmp46, label %noassert68, label %unrolledend



noassert68:                                       ; preds = %forbody39

  %tmp57 = sdiv i32 -32768, %__key8.0

  %sext34 = shl i32 %tmp57, 16

  %sext21 = shl i32 %tmp57, 16

  %tmp76 = icmp ne i32 %sext34, %sext21

  %tmp81 = add i32 %__key8.0, 1

  br i1 %tmp76, label %forcond38, label %assert77



assert77:                                         ; preds = %noassert68

  tail call void @llvm.trap()

  unreachable



unrolledend:                                      ; preds = %forcond38

  ret i32 0

}