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If a loop iterates exactly once (has backedge count = 0) then don't

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mess with it.  We'd rather peel/unroll it than convert all of its 
stores into memsets.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122711 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner
2011-01-02 20:24:21 +00:00
parent 80220369b0
commit 8e08e73f0e
2 changed files with 24 additions and 0 deletions
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18
test/Transforms/LoopIdiom/basic.ll
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@@ -188,4 +188,22 @@ for.end: ; preds = %for.body, %entry
; CHECK-NOT: store
}
; This is a loop should not be transformed, it only executes one iteration.
define void @test8(i64* %Ptr, i64 %Size) nounwind ssp {
bb.nph: ; preds = %entry
br label %for.body
for.body: ; preds = %bb.nph, %for.body
%indvar = phi i64 [ 0, %bb.nph ], [ %indvar.next, %for.body ]
%PI = getelementptr i64* %Ptr, i64 %indvar
store i64 0, i64 *%PI
%indvar.next = add i64 %indvar, 1
%exitcond = icmp eq i64 %indvar.next, 1
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.body, %entry
ret void
; CHECK: @test8
; CHECK: store i64 0, i64* %PI
}