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b020a5ea70
Summary: If a compare instruction is same or inverse of the compare in the branch of the loop latch, then return a constant evolution node. This shall facilitate computations of loop exit counts in cases where compare appears in the evolution chain of induction variables. Will fix PR 34538 Reviewers: sanjoy, hfinkel, junryoungju Reviewed By: sanjoy, junryoungju Subscribers: javed.absar, llvm-commits Differential Revision: https://reviews.llvm.org/D38494 llvm-svn: 318050
40 lines
1.5 KiB
LLVM
40 lines
1.5 KiB
LLVM
; RUN: opt -scalar-evolution -loop-deletion -simplifycfg -analyze < %s | FileCheck %s --check-prefix=CHECK-ANALYSIS-1
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; RUN: opt -analyze -scalar-evolution < %s | FileCheck %s --check-prefix=CHECK-ANALYSIS-2
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define i32 @pr34538() local_unnamed_addr #0 {
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; CHECK-ANALYSIS-1: Loop %do.body: backedge-taken count is 10000
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; CHECK-ANALYSIS-1: Loop %do.body: max backedge-taken count is 10000
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; CHECK-ANALYSIS-1: Loop %do.body: Predicated backedge-taken count is 10000
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entry:
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br label %do.body
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do.body: ; preds = %do.body, %entry
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%start.0 = phi i32 [ 0, %entry ], [ %inc.start.0, %do.body ]
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%cmp = icmp slt i32 %start.0, 10000
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%inc = zext i1 %cmp to i32
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%inc.start.0 = add nsw i32 %start.0, %inc
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br i1 %cmp, label %do.body, label %do.end
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do.end: ; preds = %do.body
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ret i32 0
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}
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define i32 @foo() {
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entry:
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br label %do.body
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do.body: ; preds = %do.body, %entry
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%start.0 = phi i32 [ 0, %entry ], [ %inc.start.0, %do.body ]
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%cmp = icmp slt i32 %start.0, 10000
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%select_ext = select i1 %cmp, i32 2 , i32 1
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%inc.start.0 = add nsw i32 %start.0, %select_ext
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br i1 %cmp, label %do.body, label %do.end
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do.end: ; preds = %do.body
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ret i32 0
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; CHECK-ANALYSIS-2: Loop %do.body: backedge-taken count is 5000
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; CHECK-ANALYSIS-2: Loop %do.body: max backedge-taken count is 5000
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; CHECK-ANALYSIS-2: Loop %do.body: Predicated backedge-taken count is 5000
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}
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