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d923ca0cb8
Enhance SCEV to compute the trip count for some loops with unknown stride. Patch by Pankaj Chawla Differential Revision: https://reviews.llvm.org/D22377 llvm-svn: 281732
63 lines
2.1 KiB
LLVM
63 lines
2.1 KiB
LLVM
; RUN: opt < %s -analyze -scalar-evolution | FileCheck %s
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; ScalarEvolution should be able to compute trip count of the loop by proving
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; that this is not an infinite loop with side effects.
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; CHECK: Determining loop execution counts for: @foo1
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; CHECK: backedge-taken count is ((-1 + %n) /u %s)
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; We should have a conservative estimate for the max backedge taken count for
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; loops with unknown stride.
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; CHECK: max backedge-taken count is -1
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target datalayout = "e-m:e-p:32:32-f64:32:64-f80:32-n8:16:32-S128"
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; Function Attrs: norecurse nounwind
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define void @foo1(i32* nocapture %A, i32 %n, i32 %s) #0 {
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entry:
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%cmp4 = icmp sgt i32 %n, 0
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br i1 %cmp4, label %for.body, label %for.end
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for.body: ; preds = %entry, %for.body
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%i.05 = phi i32 [ %add, %for.body ], [ 0, %entry ]
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%arrayidx = getelementptr inbounds i32, i32* %A, i32 %i.05
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%0 = load i32, i32* %arrayidx, align 4
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%inc = add nsw i32 %0, 1
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store i32 %inc, i32* %arrayidx, align 4
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%add = add nsw i32 %i.05, %s
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%cmp = icmp slt i32 %add, %n
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br i1 %cmp, label %for.body, label %for.end
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for.end: ; preds = %for.body, %entry
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ret void
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}
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; Check that we are able to compute trip count of a loop without an entry guard.
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; CHECK: Determining loop execution counts for: @foo2
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; CHECK: backedge-taken count is ((-1 + (%n smax %s)) /u %s)
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; We should have a conservative estimate for the max backedge taken count for
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; loops with unknown stride.
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; CHECK: max backedge-taken count is -1
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; Function Attrs: norecurse nounwind
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define void @foo2(i32* nocapture %A, i32 %n, i32 %s) #0 {
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entry:
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br label %for.body
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for.body: ; preds = %entry, %for.body
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%i.05 = phi i32 [ %add, %for.body ], [ 0, %entry ]
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%arrayidx = getelementptr inbounds i32, i32* %A, i32 %i.05
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%0 = load i32, i32* %arrayidx, align 4
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%inc = add nsw i32 %0, 1
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store i32 %inc, i32* %arrayidx, align 4
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%add = add nsw i32 %i.05, %s
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%cmp = icmp slt i32 %add, %n
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br i1 %cmp, label %for.body, label %for.end
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for.end: ; preds = %for.body, %entry
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ret void
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}
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