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

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Thanks to Andy for catching this.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@168921 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Benjamin Kramer 2012-11-29 19:07:57 +00:00
parent b36be80510
commit 7d4253af16
2 changed files with 52 additions and 4 deletions
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7
lib/Analysis/ScalarEvolution.cpp
View File

@ -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) {

49
test/Transforms/IndVarSimplify/eliminate-comparison.ll
View File

@ -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
}